US2049369A - Lockstitch sewing machine - Google Patents

Description

' July 28, 1936.

J. GOULDBOURN ET AL LOCI/(STITCH SEWING MACHINE Filed Jan. 12, 1934 7 Sheets-Sheet l Wflness 1 /6.

I July 28, 1936. J. GOULDBOURN ET AL 9,

' LOCI STITCH SEWING MACHINE Filed Jan. 12, 1934 7 Sheets-Sheet 2 July 28, 1936; J. GOULDBOURN E-f AL 2,049,369

\ LOCKSTITCH SEWING MACHINE Filed Jan. 12, 1934 '7 Sheets-Sheet 5 July 28, 1936.

J. GOULDBOU RN ET AL LOCKSTITCH SEWING MACHINE '7 Sheets-Sheet 4 Filed Jan. 12, 1934 25 9 rTa y 1936. J. GOULDBOURN ET AL LOQKSTITCH SEWING MACHINE Filed Jan. 12, 1954 7 Sheets-Sheet 5 y 28, 9 J. GOULDBOURN ET AL LOCKSTITCH SEWING MACHINE Filed- Jan. 12, 1934 7 Sheets-Sheet 6 yz 1936- V J. GOULDBOURN ET AL 2,049,369

LOCKS-TITCH SEWING MACHINE Filed Jan. 12,, 1934 7 Sheets-Sheet 7 Patented July 28, 1936 UNETED' STATES PATENT OFFICE Leicester, England,

and Nathan Freeman Hopkins, Rockland, Mass, assignors to United Shoe Machinery Corporation, Paterson, N. J., a corporation of New Jersey Application January 12, 1934, Serial No. 706,444 In Great Britain February 2, 1933 13 Claims.

This invention is concerned with improvements in or relating to sewing machines and is particularly, but by no means exclusively, concerned with sewing machines suitable for oper- 5..',-ating on thick stubborn materials such as leather.

In co-pending application of Joseph Gouldbourn, Frank B. Keall and Thomas A. Kestell Serial No. 688,480 filed September '7, 1933, there 10 is disclosed a machine for sewing the outsoles of welted boots or shoes to their welts by a lockstitch seam, which machine has thread handling and work feeding instrumentalities arranged to enable the machine to operate smoothly at a lfigrelatively high speed.

While'such a machine as is last referred to has been found to elfect very good stitching at relatively high speeds we have found it possible still further to improve the efliciency of the 20 stitching operation of the machine by modifying the action of certain of the thread handling instrumentalities. I

In a machine arranged as disclosed in the prior specification above referred to a rotary 25 shuttle of the type disclosed in the co-pending application of Joseph Gouldbourn and Thomas A. Kes-tell Serial No. 630,044 filed August 23, 1932 upon which Patent No. 1,991,456 issued February 19, 1935 is used and although such a g 30 shuttle is found to operate satisfactorily in looping the needle thread over the shuttle thread it is found, when using such a shuttle, that uniform results in the setting of the stitch locks formed between the needle and shuttle threads within 35 the work may not in some circumstances always be obtained.

Such a shuttle as is above referred to has a nose projecting downwardly from the bobbin case and the thread is arranged to pass out of .,the bobbin case through a hole in the end of the nose. The bobbin case is allowed to vibrate somewhat about the axis of the bobbin during the running of the machine to allow forward limbs of the loops of needle thread lifted over 45 the shuttle to pass between the forward side of the bobbin case and a relatively fixed ridge which engages loosely in a V-shaped groove formed in the front wall of the bobbin case. The said vibration of the bobbin case is effected 50 by the friction between the bobbin case and the rotating shuttle case, and by the action of the forward limb of the loop of needle thread in passing between the said fixed ridge and the sides of the V-shaped groove in the bobbin case. 55 :The vibration of the bobbin case is found to vary in extent during different cycles of the machine and therefore imparts an oscillating movement of inconstant amount to the said nose which, as it moves to and fro, causes small and inconstant amounts of thread to be drawn 5 ofi the bobbin in successive machine cycles, which inconstant amounts are used up in the formation of successive stitches.

Furthermore, since the movements of the said nose are only controlled in a non-positive manner, it is liable to happen during the actual setting of successive stitch locks within the work that the nose, during the setting of one stitch lock, may be rising away from the work and therefore exerting a tension on the shuttle thread and pulling additional thread off the bobbin and, during the setting of the next stitch lock, may descend towards the work and relieve somewhat the tension on the shuttle thread and pay out additional shuttle thread. Therefore, there is a tendency for the actual lengths of thread extending from the nose to the work during the setting of successive stitch locks to vary and also for the tensions in the shuttle thread to vary at these times. i

We have found that relatively slight variations in the slackness or tautness of the shuttle thread during successive stitch-setting operations causes relatively great differences in the depths to which the successive stitch-locks can be set within the work by a uniform tension exerted on the needle thread. It is one of the objects of the present invention to avoid or at least minimize variations in the slackness or tautness of the shuttle thread during successive stitch-setting operations. The action of drawing the shuttle thread on to the work by the loop of needle thread after the latter has passed over the shuttle, acting as it does in the machine disclosed in the prior specification first mentioned against the action of a tension device on the bobbin case, imposes an appreciable strain on the needle thread and causes substantial reeving of the two threads round each other which is likely to weaken the threads and mar the appearance of the threads in the finished stitch.

In a particular illustrative embodiment of the present invention hereinafter described, the tendency for the threads to reeve around each other as the shuttle thread is being drawn down on to the work by the needle thread is minimized by arranging the bobbin case in the shuttle in such a manner that as the needle thread acts to draw the shuttle thread against the work, the bobbin ating these trains of mechanism at such times" details of the'shuttle driving mechanism; Figure will approach bodily towards the work and will provide a slackness, of constant amount, in the thread extending from the bobbin to'the work. Thus, when the needle thread acts to draw the slackened shuttle thread down on to the work it will be able to laythe shuttle thread easily against the work without" causing excessive reeving between the threads since during at least part of the time when the shuttle thread is being laid against the work the movement of the shuttle; thread towards the work will not be restrained,

by the tension device on the bobbin case.

In the machine disclosed in the prior specification first mentioned upper and lower thread looking devices are used which operate alternately to grip the needle thread between the thread supply and a thread measuring device and between the thread measuring device and the looper respectively at certain times in the machine cycle.

These devices are so operated in that machine that almost as soon as one of them has gripped the thread, the other disengages the thread-so that only one of the two devices is in gripping engagement with the thread-at substantially all times. this'manner have hithertobeen accepted as satisfactory, there nevertheless arises a danger, particularly when a machine incorporating such devices is run at relatively high speed, that owing .to the rapiditywith'which the needle thread is handled by the various instrurnentalities of the machine, thread may steal through that one of the two threadlocking-devices which is grippingthe thread at a particular time or through both Blocking-devices at thetime when one is coming into grippingengagement with the thread.

It is a further object of the present invention so to arrange'and actuate upper and lower thread locking devices arranged'respectively between the supplyof needle thread and-the thread measuring device and between the measuring device and the stitch forming instrumentalities' that both locking devices are in gripping engagement with the needle thread simultaneouslythroughout substantial portions of a cycle of the machine, thus giving a more positive control of thethread. In the illustrative embodiment of the'present invention'hereinafter describedthis result is achieved by providing independent trains of mechanism for actuating-each device separately and by actuthat both devices remain'in gripping engagement with the thread throughout substantial portions of each machine cycle. V

In order that-the nature of the present invention maybe morefully understood, the illustrative embodiment aforementioned will now be described. I v

Figure 1 is a vertical sectional view illustrating the construction and relative arrangement of some of the principal parts of a machine embodying the several features of the present invention; Figure '2 is a sectional plan view of the machine illustrating particularly the shuttle driving mechanismgFigure 3 is an end" view showing certain l is a front elevation, partly in section, of thread locking means according to'the present invention; Figure 5 is a-left-hand side elevation, partly-in section of part-of thelocking mechanism shown in Figure 4; Figure 6 is a front' elevation of a shuttle arrangement according to the present invention and thread handling devices of an outsole stitchingmachine'in, the relativepositions While thread locking devices operated in has been drawn away from the shuttle; Figure 7 is a view similar to Figure 6 but with the parts in the relative position they occupy when the loop of needle thread has been drawn down to the work; Figure 8 is a sectional elevation of shuttle driving mechanism according to the present invention; Figure 9 is a plan View partly in section of some of the parts shown in Figure 8; Figures 10 and 11 are detail views of parts shown in Figures. 8 and 9; and Figures 12 to 23 inclusive are diagrammatic views illustrating the successive positions'taken by the shuttle, take-up, thread locks and pull-off during the formation of a stitch.

The illustrative embodiment will be considered as comprising an outsole stitching machine which, except in so far as is hereinafter indicated, has thread handling instrumentalities and other cooperating members substantially identical with and arranged to operate in the same manner as those of the machine disclosed in the specification of" application No. 688,480. 7

The shuttle case i of the illustrative embodiment, while being of the same general construction as the shuttle case of the machinedisclosed in application Serial No. 630,04ehas a bobbin case 3 mounted in it of somewhat different construction. The bobbin case 3 (and therefore the bobbin which it contains) is also mounted in the shuttle case'in'a somewhat difierent mannerfrom that of thebobbin case described in the specification of'Patent No 1,991,456.

The bobbin case 3- of the illustrative embodiment isheldfrom complete rotation with the shuttlecase by a fixed ridge engaging loosely in a V-shaped groove in the front wall of the bobbin againstthe outer face of the side wall of the bobbin case instead of being formed in the free end of the nose as described in Patent No. 1,991,456.

' Thus the exit hole i in the front wall of the bobbin case for the shuttle thread is, in-the present illustrative embodiment spaced only about half Way between the-axis of the bobbin case and the free end of the nose. Thus, as the bobbin case vibrates to and fro during the running of the machine, the amount of thread pulled off from the bobbin due'to the oscillations of the thread exit hole in the present illustrative embodiment are substantially less than the-amounts pulled off by the oscillations of the thread exit hole when the latter is formed in the end of the nose, as de-j scribed in Patent-N0. 1,991,456, and thus the variations in theslackness or tautness of the shuttle thread during the setting of successive stitch locks in the present illustrative embodiment will 'be' substantially less than occur when a bobbin case of the type disclosed in the application last 7' disclosed in Patent No. 1,991,456, this nose serves purely to prevent the shuttle thread, if for any reason it should becomeunduly slack, from bending sofar rearwardly as to become liable to be caught by the beak 9 of therotating shuttle. It willbe understood that, as in the case of the shuttle-referred to as'being described in Patent {shuttle case.

No. 1,991,456, the thread passes outwardly from the bobbin, through a hole in the side wall of the bobbin case and around the outside of the wall to the exit hole I in the nose which is close to the side wall of the bobbin case, the thread, as it passes between the hole in the side wall of the bobbin case and the exit hole, passing through an adjustable tension device arranged on the outside of the side wall of the bobbin case.

The said thread exit hole 7 is so positioned on the bobbin case that it lies close to the lowest point on the bobbin case and substantially on a line drawn from the centre of the shuttle case to the needle hole in the work into which a stitch lock formed between the needle and shuttle threads is being drawn by the tension on the needle thread during the setting of a stitch.

:In the shuttle disclosed in Patent No. 1,991,456, the bobbin case is mounted in the shuttle case I in a housing which is concentric about the axis ofthe shuttle case but in the shuttle of the illustrative embodiment now being described the bobbin case 3 is mounted in the shuttle case I in a housing which is eccentric about the axis of the For this purpose the pin secured to the shuttle case is ofiset about three thirtyseconds of an inch from the axis of rotation of the shuttle case, the axis of the said pin lying on a line drawn from the axis of rotation of the shuttle case I to the forward end of the beak 9 of the shuttle and between the axis of rotation bin case concentrically with the latter.

By arranging the bobbin case 3 eccentrically in the shuttle case I and by arranging the supporting pin for the bobbin case to be ofiset from the axis of the shuttle case along the particular direction above mentioned, certain desirable results hereinafter specified are achieved during the formation and setting of a stitch, as will be apparent from an inspection of Figures 6 and 7 and Figures 12 to 23. The shuttle case I of the illustrated machine is given two complete rotations at a vary ing speed during each stitch forming cycle, the connections for driving the shuttle (see Figs. 2 and 3) comprising oiTset shafts IE] and I2, cranks I4 and I 8' on the shafts and a connecting link I8. The shuttle case is so arranged in the machine that as the setting of a stitch is being completed the beak 9 of the shuttle has passed through the lowest point in its path and is commencing to rise, the thread extending at this time from the exit hole I in the bobbin case 3 to the work, lying substantially in a plane which extends from the needle hole in the work, into which the shuttle thread is being drawn by the needle thread, through the axis of rotation of the shuttle case and also through the end of the shuttle beak and the axis of the pin which carries the bobbin case.

When the setting of the stitch has been substantially completed continued rotation of the shuttle case I, acting through the eccentric pin carrying the bobbin case 3, causes the bobbin case to lift bodily and the stitch having been more or less completely set and, the needle thread still being under tension and therefore assisting in preventing the thread look from being drawn upwardly out of the needle hole, causes a certain amount of thread to be drawn off the bobbin. When the shuttle case has rotated through one hundred and eighty degrees from the position last mentioned, the lifting of the bobbin case will, sinceit is offset three thirty-seconds of an inch from the axis of the shuttle case, have caused some three sixteenths of an inch of thread to be pulled off the bobbin against the action of the tension device on the bobbin case. As the beak of the shuttle case descends once more towards its lowest position, the bobbin case will descend towards the work and will pay out into the length of shuttle thread extending between the bobbin and the work the three sixteenths of an inch of thread which was drawn 01f the bobbin after the completion of the previous stitch setting operation. The thread drawing-01f and paying out movements of the bobbin case just above mentioned will take place during the first half of each stitch forming cycle of the machine but as, after the completion of the setting of the previous stitch, no drawing down on to the work of the shuttle thread by the needle thread takes place until during the second haif of a stitch forming cycle (during which second half the shuttle makes a further complete rotation) the paying out of the said portion of shuttle thread during the first half of the cycle is idle.

As the shuttle rotates once more during the second half of the machine cycle, the shuttle beak 9 engages the loop of needle thread, held open for it by the needle I I and thread lifter i3, and rises to lift the said loop over the shuttle. .As the shuttle beak rises, the bobbin case 3 also rises bodily (due to its eccentric mounting in the shuttle case) and draws taut the slackened thread passing from the shuttle to the work. When the loop of needle thread has been lifted over the highest part of the shuttle, the continued rotation of the shutle causes the shuttle beak 9 to commence to descend towards the work and causes the bobbin case 3 likewise to commence to descend towards the work. As the shuttle beak and bobbin case descend in unison towards the work, the loop of needle thread will be drawn down towards the work over the shuttle, and round the thread issuing therefrom, by the rotary take-up device of the machine, which take-up device is the same in construction, arrangement, and operation as the take-up device disclosed in application Serial No. 688,480, and the bobbin case will once more be rapidly paying out towards the work the amount of thread drawn off from the bobbin during the first half of the machine cycle. Thus the nearer the shuttle beak approaches towards its lowest position and the further the loop of needle thread is drawn down over the shuttle, the more slack will the shuttle thread extending down to the work become. The loop of needle thread is actually pulled off the shuttle by the rotary take-up device, some eighty to ninety degrees in the rotation of the shuttle before the shuttle beak again reaches the position it occupies when the next stitch setting operation is completed and when the loop of needle thread is pulled oif the shuttle and into contact with the shuttle thread, which it straddles, the descending bobbin case will already have paid ofi about half of the amount of thread pulled off the bobbin at the conclusion of the previous stitch forming cycle. The shuttle thread will therefore already be in a slackened condition when it is engaged by the loop of needle thread and the latter can therefore commence to pull it towards the work without causing any appreciable reeving of the two threads together and without having to overcome substantial tension exerted on the shuttle thread. As the loop of needle thread continues to be pulled down towards ,the work by the take-up device, the bobbin movesstill further downwardly andzpaysr-ofi still pulling the shuttle thread against the work to lay it on the latter practically the whole amount of the thread pulled oil the. bobbin'after the conclusion of the last stitch setting operation'x'willhave been paid out and'the thread passingifrom the shuttle to the work willbe relatively slack;

Therefore as the needle thread continues to lay the shuttle thread on to the work, which action takes place as the work is being. fed towards the shuttle by work clamping members of the machine, the slackened shuttle thread falls into a condition in which it can be easily'laid against the work without exercising any substantial tension on the needle thread andwithout'causing any appreciable reeving of the two threads together. The amount of thread pulled off the bobbin and paid out by the rising and falling bobbin is .of such alengtliii; e'. is three sixteenths'of an. inch long as previously indicated) that when sewing stitches of average length, all the slackness thrown into the shuttle thread in a single cycle will have been used up in a single stitch formation or in stitch setting by'the end of the stitch setting operation.

ened as it is engaged by the needle thread and pulled down on to the work very small resistance will be offered by the shuttle thread-to being laid on the work, thus making for good stitch-making and avoiding uneven setting of the thread locks within the work.

Immediately after a setting of a stitch is completed thebobbin case will, as above described, commence to riseto pull off thread from the bobbin for the formation of the next stitch.

In the machine disclosed'in prior application No. 688,480 the shuttle is arranged to be rotated ed in a cam-member rigidly secured to the upper;

end of the shaft, conical lower ends of which spring pressed piungers engage in depressions in theupper face of the spiral gear. Such an: arrangement was intended to couple the spiral gear normally to the shaft so that the gear rotates with the shaft but to allow the gear to remain stationary if for any reasonrotation of the shuttleshould be obstructed. This arrangement, while satisfactory when the machine runs at a moderate speed, has been found at a relativelyhigh speed; not to provide as reliable a driving connection between the gear and shaft as is desired and accordingly in the illustrative embodiment now being described, four spring-pressed plungers l5 (Figures 8 and '11) are provided in the said cam member l'l' the lower ends of which are bevelled to provide chisel-like ends 19, the lengths of which lie radially of the vertical shaft. A ring 2l-secured E9 of the plungers l5 which are arranged to en-- gage within them. Since in the present illustrative embodiment four spring-pressed plungers-l5 having chisel shaped lower ends ane arranged to couple the gear2 3 to the vertical shaft- 759 2 a more positivedriving connection between the gear and'ithis shaft is obtained thereby guard-' ingefiectively'against relative slip occurring be tween the gear and the shaft during the normal operation-of, the machine while still allowing the V shaft to rotate relatively to the said gear if the shuttle should at any time becomejammed against. rotation. Relatively strong springs 29 are provided above the spring pressed plungers l5 to maintaintheir lower'ends pressed firmly in the grooves in the ring secured to the said spiral gear.

As before stated, the shuttle is rotated twice each: cycle ofv the machine and it is necessary, in

order that the correct timing of the'shuttle in' theme-chine shall be regained if relative slip has:

occurred for any reason between the spiral gear? and the vertical shaft, that the said gear should until each plunger once more comes into line with the same groove in the ring secured to the,

spiral gear as it engaged before the slip between the verticalshaft and the spiral gear occurred or until-it comes into line with a groove lying dia-- metrically opposite said groove. In order to ensure that the gear. 23' will become coupled to the shaft 2'! only in one or: other of these two-positions, two lugs M are formed on the outer edge of said ring 21 and lie at the outer ends of two of the, grooves whichlie diametrically opposite each other and two similar lugs 33 are formed on the inner edge of the ring 2i and lie at the inner ends of the other two grooves. Each of the two plungers which engage in the two grooves first above mentioned has an enlargement 35 formed on that'side of its lower bevelled end 1 which lies nearer the axis ofthe said vertical shaft and each of the other-two plungers which engage in the two grooves last above mentioned has an enlargement 31 formed on-that side of its lower bevelled end which lies further from the axis of the vertical shaft. The arrangement is such that if relative slip has occurred between the rotary shaft 21 and the said gear 23, the lugs 33'formed onthe inner edge of the said ring will prevent the plungers l5, whichhave enlargements 35 formed on their lower ends nearer to the axis of thevertical shaft from entering the grooves adjacent these lugs but will'allow those plung ers having enlargements 37 formed on the outer sides of their lower ends to enter the saidgrooves. Similarly the lugs 3i formed on the outer edge of the ring 2i while allowing those plungers which have enlargements 35 formed on the inner sides of their lower ends to enter the grooves will nevertheless prevent the plungers which have enlargements 3! formed on their outer sides from en-- tering the grooves adjacent them. (As shown in Figures 10 and 11.)

Theillustrative embodiment is,like the machine disclosed in application No. 688,480 provided with two thread locking devices arr'anged'one to grip the needle thread between the supply and a thread measuring device or pull-off and ,the other between the thread measuring device and the stitch 1 thread locking'devices'of the present illustrative embodimentare: like the devices of the machine disclosed in the prior specificationlast-referred measuring device and the stitch forming instruto, in that that one (hereinafter termed the lower or rear thread lock) which engages the needle thread between the supply and the thread measuring device comprises a' relatively fixed thread-engaging plate ii (Figure 4) against which the thread is clamped by a cooperating plate &3 which is moved yieldingly horizontally towards it and the other locking device (hereinafter termed the upper or front thread lock) which engages the thread between the thread mentalities comprises a relatively fixed roll 45 over which the thread passes and a thread-engaging shoe 5? which is arranged to be lowered towards the roll to press the thread against the upper face of the roll. In the present illustrative ,embodiment, however, two separate cam grooves are provided ina cam member 49 which is secured to a driving sleeve for the rotary take-up device aforementioned and one of these cam grooves actuates a cam lever 5! which is coupled to the upper thread lock and the other cam groove actuates a second cam lever 53 which is coupled to the lower thread lock, the connections from the two cam levers to their respective thread locks being separate and unconnected so that the two locks are operated independently of each other. The movable member-of each of the thread locks is moved yieldingly to grip the thread at certain times in the machine cycle against its cooperating stationary member through a spring plunger arrangement 55 included in the.connections which connect it to its actuating cam lever but the movable members are arranged to be moved out of engagement withthe thread at the appropriate times in the machine cycle bya pin and slot connection 51 with the spring plunger which, when the spring behind the plunger, has

expanded to its original condition after the pressure of the movable member of the thread lock on the thread has been released, causes the movable member to move positively somewhat away from its cooperating fixed member, thus ensuring that actual separation of the cooperating members occurs at the desired times in the machinecycle. In the case of the lower look, however, the movable member may be moved positively, i. e. unyieldingly, by its actuating mechanism and its cooperating relatively'fixed member 'may yield against a spring as the movable member presses the thread against it. Such an arrangement tends to minimize the hammering action which the movable member exerts on the thread as it moves rapidly to grip the thread. The separate actuating mechanism for the upper and lower, thread locks are arranged to act in such time relation relatively to each other and to the'operation of the stitch forming instrumentalities of the machine that not only do both thread locks grip the thread simultaneously throughout relatively'long portions of the machine cycle during which there is a danger that thread might steal through the looks but also each lock, considered separately, is caused to engage the thread at especially convenient times 1 in a cycle of the machine.

The particular times in the machine cycle at which the two locks grip and release the needle thread independently will now be indicated. In

Referring to Figures 12 to 23 and assuming the machine to be in operation sewing an outsole to a shoe and the stitch forming instrumentalities to have reached the positions they occupied when the machine was at rest, the take-up roll 42 of the rotary take-up device will be commencing to set the thread lock of the stitch last formed within the work. At this time the lower thread lock is in gripping engagement with the needle thread, the upper thread lock being open at this time but being ready to close. During the next few degrees of rotation of the main shaft (e. g. during about twenty degrees of rotation of the main shaft from its stopping position) the takeup roll will have imparted the maximum tension to the needle thread stretching the latter somewhat during the final setting of the stitch and the upper thread lock will have been closed and will have firmly gripped the thread; the bottom lock still remaining closed. The take-up roll will have imparted the maximum tension to the thread only just before the upper lock is firmly closed upon the thread and will preferably commence to rise towards the work to pay out thread ready for the formation of the next stitch only after the upper lock actually has closed. The fact that the take-up roll will have imparted the maximum tension to the thread and will have stretched the thread before the upper lock closes would give rise to the danger that when the take-up roll moves towards the work after having tensioned the thread, the tensioned thread, which will not instantaneously recover its unstretched condition, would, if the upper lock were open at that time, steal back somewhat through the top lock thus rendering the next thread measuring operation inaccurate and producing inaccurated setting of the next thread look within the work. Since, however, the upper thread lock in the present illustrative embodiment is caused to grip the thread almost immediately after the take-up roll has imparted the maximum tension to the needle thread, the danger of thread stealing back through the upper look as the takeup roll rises towards the work is either obviated or at least very substantially minimized. Since there is substantially no movement of the thread over the stationary roll of the upper lock taking place when the upper lock closes, there is no danger that reeving of the thread through the lock will take place at that time. The upper lock grips the thread so soon after the take-up roll has imparted the maximum tension to it that it grips the thread while a considerable portion of this tension still remains in the thread and therefore the portion of needle thread extending between the upper and lower locks is taut when the upper lock grips the thread.

Both the upper and lower locks remain gripping the thread simultaneously until, when the take-up roll has risen somewhat towards the work and the machine shaft has rotated through about a hundred degrees from its stopping position the thread measuring device, which comprises a roll indicated at 44 and which is constructed, arranged and actuated as in the machine of application Serial No. 688,480, is ready to draw oil from the supply the necessary amount of needle thread for the formation of the next stitch. The lower look there upon opens, while the upper lock remains gripped on the thread, and remains open while the main shaft of the machine rotates through about a further hundred and thirty degrees, during which time the thread measuring device operates to pull the necessary amount of thread from the supply through the open bottom lock. Just about this time the shuttle beak enters the loop of needle thread pulled upthrough the work by the needle, this pulling up of the needle loop being allowed by reason of the-rising of the take-up roll while the upperlock still remains closed. Immediately'afterthe thread-measuring device has completed its thread pulling off movement (1. e. when the main-shaft has rotated through two hundred and thirty degrees approximately) the lower lock closes'and the thread pulled off the supply by the measuring device remains locked between the upper and lower thread locking devices. Both the upper and lower locks remain simultaneous- 1y gripping the thread until the main shaft has then becomes unlocked while the lo-werlockstill remains gripped upon the thread. The lower lock remains in gripping engagement with the needle thread throughout the remainder of the cycle and until, in the next cycle, just before the threadmeasuring device operates once more to draw -ofi thread-from the supply.

Fromthe description'above given of the relative times in the machine cycle at which the upper and lower thread locks are respectively closed and-opened, it will be seen that between the time when the take-up roll imparts the maximumtensionto the thread and the time when the thread measuring device commences to pull off needle threadfrom the supply, both the upper and lower locks remain in gripping engagement with the needle thread during arotation of the main shaft through about eighty degrees. It will further be seen that during the period of time that elapses after the threadmeasuring device has pulled off the necessary amount-of thread from the supply but before the take-up roll imparts the maximum tension to the thread,both locks will remain in gripping engagement with the thread'during about a rotation of the main shaft through about sixty-five degrees. Since the lower lock does not close until after the thread measuring device has concluded its thread-pulling off function, at which time the upper lock is closed, no movement of the thread through'the lower lock is taking place as the lower lock closes and therefore objectionable reeving of the thread through the closing lock is obviated. Since thetwo locks'are simultaneously in gripping engagement with the 'thread-throughoutrelatively large portions of the cycle each lock will have ample time to settle itself firmly on the thread before the other lock opens.

It will be appreciated that if the movable members of the upper and lower locks were always moved, towards their cooperating stationary members-to grip the'thread between them from constant positions away from the stationary mem bers whatever the thickness of the needle thread notronly would the intensity of the gripping ac tion of the locks on the thread vary with threads of different thicknesses but also the space providedbetweenthe movable and stationary memrelatively thick one.

bers of the locks when-the'latter are open would "be greater than is necessary when the needle thread is a relatively fine one and might be less 1 than is desirable when the needle, thread is a V In order that a uniform 5 clearance may be. provided between the thread, whatever the thickness of the latter, 'and'the thread engaging members of the looks when the latter are open and also inorder that the precise times in the machine cycle at which the locks actually grip'the thread may be the same for all thicknesses of thread, an eccentric setting is provided for-the movable member of eachlock byadjustment of which the position.from;.which the movable member starts to move'towards its cooperating stationary member can be adjusted without disturbing the times at which the movable member nism.

The eccentric settingfor the upper thread lock comprises a .sleeve 5.9 rotatably mounted in a bearing in abracket 61. 'The sleeve 59 has eccentrically mounted in it a spindle 6.3 rotation of which moves the thread-engaging shoe 4'! to-,

'wards or from the fixed roll 45. The sleeve 592 has extending from-it an arm 65 having formed in ita slot '61 through which passes a screw '69 threaded into "the bracket '6 I. i691isslackened, the sleeve 59 may be .rotated by means of the arm 65 to adjust the shoe 4.! towards t or, from the roll 45. The eccentric setting of the lower. threadelock comprises a studtlLwhich is secured in thecam lever 53 and having an eccentrio portion 73 on which is mounted acam roll 15 engaging inone of the cam grooves inthe cam block 49. .By rotating the stud H, the plate '43 may be adjusted towards or from the plate 4|.v

' .As inthe caseofthe machine disclosedin prior :application No,688,480,.themachine of the i11ustrative embodiment comeslto a stop while theam lower thread lock is closed upon-the thread and mechanism connected to the'stop motion of the machine and similar to that described in that application isembodied in the machine of the-pies- ..-ent illdstrative embodiment to open the lower thread look when the machine stops to allow the operator to draw through it inremoving thework from the machine: The said mechanism com-v prises an eccentric sleeve 11 on which the cam,

lever 53is=pivoted." The sleeve 11 is pivotedon" a pin l9'secured in bearings '81, 8| extending from the bracket BI and has extending from it .an arm 83 which is connected by a pin and slot "connection to a' rod 85. The rod "85 is connected? "to"abell-crank'leverill which is connected by a 1 rod "89 to the said stop motion of the machine.

The sleeve 71 also hasextending from it an arm 1 ill to which is connected one endof a spring 93 the other end of which is connected to the machine frame. When the clutch controlling treadle of the machine is depressed to start the machine,

the spring'93 is allowed to swing theeccentric sleeve-17 in an anti-clockwise direction, as viewed in Fig'ure l, until the arm 83 engages a plate 95 5 5 secured on one of the-bearingstl. Movement of the eccentric sleeve 17in this direction swings the cam lever 53 about theaxis of. the cam roll '15 and moves the plate 43 towards the plate 4| into a position from which it can be moved by the aft cam lever 53 when it is aotuatediby its cam at the appropriate time in the machine cycle towards the plate 4! to grip, the thread. As'the is actuated by its operating mecha- 7 When the screw machine comes to rest, the eccentric sleeve 11 is} swung in the opposite direction and causes the -7 pendently of the lower lock, it may, if desired,

be arranged to grip the thread somewhat earlier in the machine cycle than above set forth in order that the upper and lower thread locks may both be gripping the thread just previous to and during the time that the take-up device is imparting the maximum tension to the needle thread during the setting of the stitch so that greater resistance to drawing of the thread through the looks at this time may be secured. If, however, the upper lock is arranged to grip the needle thread some little time before the take-up device imparts the maximum stretch setting tension to the needle thread, it will happen that when the machine comes to a stop not only will the lower lock be gripping the thread, but the upper lock will also be gripping the thread and consequently it will be necessary to include in the machine mechanism which may be similar to that for opening the lower look when the machine stops, for opening also the upper'lock at this time.

The nature and scope of the invention having been indicated, and a machine embodying the several features of the invention having been specifically described, what is claimed is:

1. A lockstitch sewing machine having, in combination, stitch forming devices comprising a needle, a shuttle, a take-up, a pull-off, a front thread lock between the take-up and pull-01f, a rear thread lock between the pull-off and the supply, and means for actuating the parts to cause the take-up to set the stitch while the rear thread lock is closed and to close the front thread look while the thread is being strained by the take-up.

2. A lockstitch sewing machine having, in combination, stitch forming devices comprising a needle, a shuttle, a take-up, a pull-off, a front thread lock between the take-up and pull-01f, a rear thread lock between the pull- 01f and the supply, and means for actuating the parts to cause the pull-off to pull thread from the supply while the front thread lock is closed and while the rear thread lock is open, and to maintain the front thread lock closed until the needle looprear thread lock between the pull-off and the supply, and means for actuating the parts to cause the take-up to set the stitch while the rear thread lock is closed, to close the front thread look while the thread is being strained by the take-up, to cause the pull-01f to pull thread from the supply while the front thread lock is closed and while the rear thread lock is open, and to maintain the front thread lock closed until the needle loop passes over the top of the shuttle.

4. A lockstitch sewing machine having, in combination, stitch forming devices comprising a needle, a shuttle, a take-up, a pull-off, a front thread lock between the take-up and pull-01f, a rear thread lock between the pull-off and the supply, and means for actuating the parts to cause the take-up to set the stitch while the rear lock is closed and while the front lock is open and to cause the pull-off to pull thread from the supply while the front lock is closed and while the rear lock is open, and means for varying the time during the stitch forming cycle at which the locks are actuated.

5. A lockstitch sewing machine having, in combination, stitch forming devices comprising a hook needle, a discoidal shuttle having a loop taking 5 beak and a thread case mounted in the shuttle provided with an opening for the passage of the shuttle thread from the thread case to the Work and formed with a radially projecting nose extending beyond the thread opening into a position to hold the shuttle thread out of the path of the shuttle beak. v

6. Alockstitch sewing machine having, in combination, stitch forming devices comprising a needle, a shaft making one rotation during each1'5 stitch forming cycle, a gear on the shaft, a rotary shuttle driven from said gear and a slip driving connection between the gear and the shaft comprising a plurality of spring plungers mounted on the shaft and provided with chisel-like ends en- "20 gaging radial grooves in the gear.

7. A lockstitch sewing machine having, in combination, stitch forming devices comprising a needle, ashaft making one rotation during each stitch forming cycle, a gear on the shaft, a multiple rotary shuttle driven from said gear, a slip driving connection between the gear and the shaft comprising a plurality of spring plungers mounted on the shaft and arranged to engage at their ends with equally spaced recesses in the gear, and means acting during the relative rotary movement of the shaft and gear to permit engagement of each plunger with a portion only of said recesses.

8. A lockstitch sewing machine having, in combination, stitch forming devices comprising a needle, a shaft making one rotation during each stitch forming cycle, a gear on the shaft, a twoto-one rotary shuttle driven from said gear, a slip driving connection between the gear and the shaft comprising four spring plungers mounted on the shaft and provided with chisel-like ends engaging equally spaced radial grooves on the gear, and means acting during a relative rotary movement of the shaft and gear to permit engagement of each plunger with diametrically opposite grooves only.

9. A lockstitch sewing machine having, in combination, stitch forming devices comprising a needle, a shaft making one rotation during each stitch forming cycle, a gear on the shaft, a multiple rotary shuttle driven from said gear, a slip driving connection between the gear and the shaft comprising a plurality of spring pressed plungers mounted on the shaft and arranged to engage at their ends with recesses in the gear, and lugs on the shaft cooperating with the plungers during a relative rotary movement of the shaft and gear to permit engagement of each plunger with a portion only of said recesses.

10. A lockstitch sewing machine having, in combination, stitch forming devices comprising a hogked needle, a take-up acting during each stitch forming cycle to pull a loop of needle thread from the shuttle and set the stitch, a ro- 65 tating discoidal shuttle, means actuated by the rotation of the shuttle to pull off and give up shuttle thread, and means for rotating the shuttle in timed relation to the take-up to cause thread to be pulled from the shuttle after a stitch has been set by the take-up and while tension is being exerted on the set stitch by the take-up and to give up thread while the next needle loop is being drawn from the shuttle into the work by the take-up.

11. A lockstitch sewing machine having in combination, stitch forming devices comprising a hooked needle, a take-up acting during each "stitch forming cycle to pull a loop of needle thread from the shuttle and set the stitch, a rotating discoidal shuttle, a none-rotating bobbin case mounted eccentrically in the shuttle acting to pull off and give up shuttle thread during the rotation of the shuttle, and means for rotating the shuttle in timed relation to the taker-up to cause thread to be pulled from the shuttle after a stitchhas been set by the take-up and while'tension is being exerted on the set stitch by the take-up and to give up thread while the next needle loop is 'being drawn from the shuttle into the Work by the take-up. 12. A lockstitch sewing machine having, 1 combination, stitch forming devices vcomprising a hooked needle, a take-up, a rotating discoidal shuttle, means for imparting a plurality of rotations to the shuttleduring each stitch form- 'ing cycle, and means actuated by the shuttle during onerrotation to pull thread from the shuttle after a stitch has been set by the take-up combination, stitch forming devices comprising a hooked needle, a take-up, a rotating discoidal shutt1e,'a non-rotatingbobbin case mounted eccentrically in the shuttle acting to pull off and give up thread, and means for imparting a plurality of rotations to the'shuttle during each stitch forming cycle in timed' relation to the takeup to cause thread to be pulled from the shuttle during one rotation after a stitch has been set by thetake-up and while tension is being exerted.

on a set stitch: by the take-up and to give up thread during a subsequent rotation of the shuttle while the next needle loop is being drawn from the shuttle into the work by the take-up.

V JOSEPH GOULDBOURNf 1 HAROLD ERNEST ELLIOTT. NATHAN FREEMAN HOPKINS.

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