US3012529A

US3012529A - Lock stitch sewing machines

Info

Publication number: US3012529A
Application number: US684922A
Authority: US
Inventors: Stanley J Ketterer; William L Herron
Original assignee: Singer Co
Current assignee: Singer Co
Priority date: 1957-09-19
Filing date: 1957-09-19
Publication date: 1961-12-12
Anticipated expiration: 1978-12-12
Also published as: GB851464A

Description

Dec. 12, 1961 s. J. KETTERER ETAI. 3,012,529

LOCK STITCH SEWING MACHINES Filed Sept. 19, 1957 5 Sheets-Sheet 1 Fig.l

INVENTORS Stanley J. Kefferer William L. Herron I BY 4 TORNEY WITNESS Dec. 12, 1961 s. J. KETTERER ETAI. 3,

LOCK STITCH SEWING MACHINES Filed Sept. 19, 1957 5 Sheets-Sheet 2 Fig.l3

Fig.2

PRIOR ART BY Luz Li TTORNEY Dec. 12, 1961 s. J. KETTERER ETAI. 3,012,529

LOCK STITCH SEWING MACHINES Filed Sept. 19, 1957 5 Sheets-Sheet 3 INVENTORS Stanley J. Kefferer WITNESS v 9 William L. Herron Dec. 12, 1961 s. J. KETTERER ETAI. 3,012,529

LOCK STITCH SEWING MACHINES 5 Sheets-Sheet 4 Filed Sept. 19, 1957 INVENTORS Stanley J. Keherer William L.Herron BY a wmvsss ATTORNEL Dec. 12, 1961 5. J. KETTERER ETAI. 3,012,529

LOCK STITCH SEWING MACHINES Filed Sept. 19, 1957 5 Sheets-Sheet 5 1 1a 1 l 19 $92 5 87 77 86 9 i 94 5 I I s5 is 4V 72745 15 15 l! 77 I27 16 Fig.9

v |o| i/ Wl as I27 76 Flg Y g' INVENTORS Stanley J. Kefferer William L. Herron WITNESS ATTORNEY Unitd States Pate" r V 3, LOCK STITQH SEWING MACHINES. Stanley J.- Ketterer, Stratiord, andWilliam L. ,Herron, Easton, Conn assignors to The Singer Manufacturing Company; Elizabeth, N 5., a corporation of New Jersey Filed Sept. 19, 1957, Ser. No. 684,922 23 Claims. (Cl.'112-181)' This invention relates to lock stitch sewing machines.

A feature of a lock stitch is that it will not ravel and therefore the term has in some cases been misapplied to a' chain stitch of the type having a plurality of threads or a peculiarity of concatenation so as to minimize the possibility of rav eling. By a true lock stitch is meant the Federal stitch type 301, in which the resulting seam is formed by separate thread'limbs one on the top and the other beneath the material with only a single strand of each thread limb extending between successive needle penetrations, both thread limbs at each needle penetration being looped together preferably at a point equidistant from the top and bottom surfaces of the material being stitched.

It is an object of this invention to provide a lock stitch sewing machine in which replenishment of the bottom or so-called bobbin thread for the stitching of a true lock stitch seam is accomplished completely automatically.

A further object of this invention is to provide a lock stitch sewing machine in which the manipulation of the machine by the operator to introduce or withdraw work fabrics, serves to meter thread for replenishment of the bottom thread limb from a supply of thread common to both the top and bottom thread limbs.

Another object of this invention is to provide a novel automatic means for holding and tensioning afresh supply of thread within the loop taker of a lock stitch sewing machine.

It is a further object of this invention to provide a cyclically operating tacking machine for producing a lock stitch tack in which the lower or so-called bobbin thread supply is automatically replenished during each cycle of machine operation.

With the above and other objects and advantages in view as will hereinafter appear, this invention comprises thedevices, combinations, and arrangements of parts hereinafter described and illustrated in the accompanying drawings of a preferred embodiment in which:

FIG. 1 represents a side elevational view of a sewing machine having the present invention applied thereto,

FIG. 2 represents a bottom plan view of the sewing machine of FIG. 1,

FIG. 3 represents an enlarged head'end elevational view of the sewing machine of FIG. 1,

FIGS. 4, 5, 6 and 7 are enlarged side elevational' views, partly-in section, of the head end portion of the sewing machine of FIG. 1 including the work fabrics and the thread, and illustrating in sequence: the position of the parts at the conclusion of a cycle of machine operation in FIG. 4, the work clamp raised for removal and reintroduction of work fabric in. FIG. 5, the needle emerging from the work after the first penetration in a new cycle in FIG. 6, and the needle beginning its downstroke for the second needle penetration in FIG. 7,

FIG. 8 represents an enlarged face view of the shuttle and thread container,

FIG. 9 represents a vertical cross sectional view of the shuttle and thread container, taken substantially along line 9-9 ofFlG. 8, with the parts arranged as for normal sewing operations,

FIG. 10 represents a vertical cross sectional View similar to FIG. 9 but with the par-tsarranged so as to receive a fresh supply of underthread,

FIG. ll represents a horizontal cross sectional new I of the shuttle and thread container taken subs'tantially along line Ill-11 of FIG; 8 and illustrating the parts arranged to receive a fresh supply of underthread as in FIG. 10, V h f FIG. 12 represents an enlarged cross sectional view of a typical lock stitch tack, as produced by a conventional sewing machine, and

FIG. 13 represents an enlarged cross sectional view of a lock stitch tack as produced by the sewing machine of this invention. 2 Referring to FIGS. 1, 2, and 3 of the drawings, this vention is illustrated as applied to a cyclically opera-ted sewing machine of the type represented, for example, in the United States patent of Barron No. 1393241, April 14, 1914, to which reference may be had fora complete understanding of the general operation of the machine. Machines of this type are commonly constructed a frame including a flat bed 11, a hollow vertical standard 12 rising from the bed, and a bracket arm 13 extending from said standard and over said bed. Iour n al ed horizont'ally in the standard and bracket arm of the frame is a main shaft 14 which serves to impart motion to-a conventional link type needle thread take up, of which athread engaging arm 15 is illustrated, and also actuatesthe usual endwise reciprocatory needle bar 16; which is jo'urna led in the bracket arm and carries a needle 17. The main shaft is formed with a crank embraced by a pitrnan 1 8 entending downwardly through the hollow standard and con; nected to one arm 19 of a two armed lever member 2!} jour'naled in the bed. The other arm 21 of the lever 20 is bifurcated and engages a slide block 22 pi-vofally secured on a rock arm 23 fast on a loop taker shaft 24 journaled lengthwise beneath the bed. Fast on the free end of the loop taker shaft is a shuttle driver 25 which serves to impart oscillatory motion to a shuttle body 26 confined to circular movement in a shuttle race member 27 carried beneath the bed. The shuttle isof the conventional type adapted to cooperate with the needle in the formation of lock stitches by taking a loop of needle thread from the needle and expanding the needle thread loop about'itself.

The shuttle illustrated in thedrawings does not have'provision for the usual bobbin of underthread about which the needle loop is passed by the shuttle in conventional lock stitch sewing machines. The shuttle, howevenin all able on the machine bed as a unit in response to; clamp shifting mechanism actuated by a pattern cam 33 rotat able with a cam shaft stained in the machine standard and adapted to be driven from the sewing. machine main shaft. vFulcjrumed on a bracket 35 carried onthe-bcdyare two

camfollow'e'rlevers

36 and 37. The follower lever 36 tracks a cam groove 38 iri'the' outer face" of the pattern cam and by means of a link 39 and a bellcranlr leverl 40 transmits motion to the work clamp transversely across the bed of the machine. The follower lever 37; tracks a cam groove (not shown) on the inside faceof the cam which'servesin a well knowii manner-to shift the won: clamp'lengthwise" of the-bed of the machine.-

The sewing machine is rendered cyclic in spanned by a stop: rriotion mechanism operativetointerr'i'ih th drive of the sewing machine andto stop 'tlie mach ne iii'a'd fi nae position ofthe parts after a prederemfiaed number of stitches have been made. On the main shaft of the machine are two pulleys, a fast pulley 50 secured for rotation with the main shaft, and a loose pulley 51 freely journaled on the main shaft. A stop motion frame 52 is pivoted to a bracket 53 on the machine standard for universal pivotal movement in the conventional manner. The stop motion frame carries a belt shipper 54 which serves to shift a driving belt (not shown) between the loose and fast pulleys and also carries a stop plunger 55 which cooperates with a stop lug formed on the hub 56 of the fast pulley to stop the machine. The stop motion frame may be turned clockwise, as viewed in FIG. 1, to start the machine by means of a starting bell crank lever 57 operable by means of a chain 58 from any conventional treadle or knee press. When turned clockwise, as viewed in FIG. 1, the belt shipper will carry the driving belt onto the fast pulley, the stop plunger will be shifted to one side of the stop lug and the machine will begin to operate. A latch lever 59 engages and holds the stop motion frame in running position. The latch lever 59 is controlled by either one of the trip points 60 carried on the inside face of the pattern cam. The pattern cam illustrated in the drawings is one in which two cycles of machine operation will occur for each revolution of the pattern cam, hence there are two tripping points 60 arranged in diametrically opposed relation on the cam.

When the stop plunger 55 is struck by the stop lug on the hub of the fast pulley, the stop frame 52 will be turned by the impact and in so doing will shift the bell crank 61 which at the end of each cycle of machine operation is positioned so as to enter an aperture in the stop motion frame. The bell crank is pivotally secured to a knife actuating slide rod 62 carried beneath the bed and the slide rod 62 carries a rack segment 63 meshing with a gear segment 64 which is rotatable with a pair of thread cutting knives (not shown). This thread cutter arrangement is similar to that described in the above mentioned Barron Patent No. 1,093,241 including the provision of a knife control lever 65 fulcrumed in a bracket on the machine bed and tracking a cam groove 66 in the outside face of the pattern cam. The control lever 65 is embracedby bifurcated fingers 67 formed on the knife slide rod 62. The control lever serves two purposes, first it serves to bring the knives into position for cutting the threads as the cycle of stitching nears an end. Second, the knife control lever carries the bell crank 61 out of register with the stop motion frame during the most of the cycle so that if the machine should be stopped accidentally before the end of the cycle, the thread cutting knives will not be actuated.

In the respects thus far described, the sewing machine chosen to illustrate the present invention follows the conventional construction of this type of machine. The shuttle body 26, however, differs markedly in its construction from that of a conventional shuttle. As illustrated best in FIGS. 8 to 10, the rear wall 71 of the shuttle body is formed with a hollow post 72 extending within the interior space defined by the shuttle body. The hollow post defines a straight cylindrical bore 73 at the inside and a cylindrical bearing surface 74 at the outside terminating into a radial shoulder 75 formed at the base of the post. Journaled snugly on the bearing surface 74 of the post is a thread container base 76 seated against the radial shoulder 75 on the shuttle post and formed with a radial flange 77 which is embraced by a gib member 78 secured to the rear wall of the shuttle by screws 79. The thread container base is thus rotatably journaled on the post 72 and constrained thereon by means of the gib member 78.

On its free extremity, the thread container base 76 is cuplike being formed along approximately one half of its periphery with a wide annular flange 80 and along somewhat less than the remainder of its periphery with a considerably narrower annular flange 81. Between the

flanges

80 and 81 substantially diametrically opposed on the thread container base are

spaces

82 and 83 in which there are no flanges. The thread container base is apertured as at 84 to accommodate a pin 85 formed with an enlarged head 86 which fits snugly into the cylindrical bore 73 of the post 72 of the shuttle. A coil spring 87 confined between the thread container base and the head 86 of the pin serves to bias the pin toward the right as viewed in FIG. 9. At the extremity opposite the head 86 the pin 85 is threaded into a thread container face or cover plate 88 of which the outside diameter is made to fit snugly within the peripheral flanges of the thread container base. A pin 89 fixed in the thread container face plate extends through a bore in the thread container base so as to lock the cover plate and base together to prevent relative turning movement one with respect to the other. The thread container face or cover plate is provided with a rotation restraining finger 90 disposed between a pair of stop members 91 carried on the shuttle race member as illustrated best in FIG. 3.

Referring particularly to FIGS. 8 to 11, the thread container face plate is formed with a substantially vertical diametrically arranged slot 92 in its inside face. Disposed within the slot and secured therein at the bottom by fastening screws 93 is a fiat thread tension spring 94. The top of the thread tension spring is urged out of the slot 92 by an adjusting screw 95 and limited by the head of a stop screw 96.

When the coil spring 87 on the pin 85 is relaxed so as to bias the face plate 88 of the thread container against the thread container base, as illustrated in FIG. 9, the face plate of the thread container will occupy substantially the same position relative to the shuttle body that a conventional bobbin case will occupy on the ordinary shuttle construction of a lock stitch sewing machine. When the shuttle parts occupy the position illustrated in FIG. 9, a loop of needle thread when engaged by the shuttle will slip over the face plate of the thread container and continue over the rotation restraining finger 90 in the same way as in a conventional shuttle.

The present invention, however, provides a means for automatically changing the arrangement of the shuttle parts so that a loop of needle thread engaged by the shuttle will not slip over the face plate of the thread container as is usual, but instead will enter between the face plate and base of the thread container, be subjected to the action of the tension spring 94, and serve as the under thread for a true lock stitch seam.

Referring particularly to FIGS. 1 and 2, the loop taker shaft 24, from the shuttle driver extremity to a point substantially midway of its length, is formed with an axial bore within which is disposed an endwise slidable rod 101. The rod 181 is preferably smaller in diameter than the head 86 of the pin 85 in the shuttle assembly and, as illustrated in the drawings, the rod 101 abuts the head 86 of the pin 85 and is in substantially axial alignment therewith. Clamped on the free extremity of the rod 101 but somewhat back from the free end thereof is a thread clamping finger 102 which, as illustrated in FIG. 6, terminates opposite the outer portion of the rear wall 71 of the shuttle body.

Referring to FIG. 2, the loop taker shaft is formed with a lengthwise extending slot 103 opening onto the bore 100 and a radial pin 104 fixed in the rod 101 extends through the slot 103 and is sandwiched between two bearing washers 105 which are embraced between the spaced fingers 106 of a block 107. The block 107 is secured to a push rod 108 which is guided in a bearing bracket 109 on the machine bed and telescopically arranged in a bore 110 of a push rod 111. A pin 112 fixed in the push rod 168 extends through a slot 113 formed in the push rod 111 to prevent relative turning movement of the push rods 188 and 111 and to limit the relative axial movement therebetween. A coil spring 114 seated within the bore 118 serves to bias the push rods 108 and 111 into extreme extended position. The push rod 111 is pivotally connected to a'lat'eral extension 115 of abell crank 116 fulcrurned on a bracket 117 on the machine bed and biased by means of a coil spring 118 into an extreme clockwise position as illustrated in FIG. 1. The bell crank 116 is a cam follower lever and carries a cam follower pin 11 9 adapted to be engaged periodically by the cam lugs 120 carried at the periphery of the pattern cam 33. The cam follower pin 119 is arranged with respect to the cam lugs 120 such that the cam follower pin is engaged and the bell crank 116 turned in a counterclockwise direction during the first needle penetration of each cycle of machine operation. More specifically, the cam follower pin 119 is arranged so as to be engaged by one of the cam'lugs 120' precisely when the shuttle is engaging the needle thread loop on the first penetration of the needle in each cycle of machine operation. Movement of the bell crank 116 in response to the cam lug 120 will shift the push rods 108 and 111 to the right as viewed in FIG. 2. By means of the bifurcated block 107 and the pin 104, the rod 101 will also be shifted to the right, the spring 114 and the slot and

pin connection

112, 113 providing for a lost motion such that the earn 120 may turn the bell crank to a degree in excess of that required to open the shuttle parts. The rod 101, in shifting to the right,-will engage and depress the pin 85 thus shifting the thread container face plate 88 outwardly with respect to the thread container base 76 and to a position as illustrated in FIGS. 6 and and 11.

At the same time the thread clamping finger 102 will shift into engagement with the shuttle body clamping therebetween the free end of the needle thread loop. The clamping finger 102 will turn with the shuttle and by thus clamping the free end of the needle thread loop, the thread at the end of each cycle may be trimmed close to the work leaving only a short end of thread extending through the eye of the needle. Since the loop will be clamped to the shuttle bodyduring the first needle penetration of each cycle, the thread will not be pulled out of the eye of the needle, and in addition, since the needle thread loop cannot slip around the shuttle, a greater amount of needle thread will be carried down with the shuttle on the first needle penetration.

The rod 101 which engages and depresses the pin 85 on the shuttle body to separate the thread container face plate 88 from thethread container base 76, is moved by the cam lug 120 an amount greater than the width of the narrow flange 81 of the thread container base but less than the width of the wide flange 80. As best illustrated in FIG. 11, the result is that a thread receiving slot 125 is opened between the thread container face plate and base through which slot one limb of the needle thread loop willenter instead of passing over the thread container face plate.- The

extremities

126 and 127 of the wide annular flange of the thread container base provide abutrnents against which the thread limb entering the slot 125 will be carried by the shuttle. As illustrated in FIG. 10, the tension spring 94 will be carried away from the thread container base bytlie stopscre'w 96 and the limb of thread entering the slot 125 will thus be located by the

abutments

126 and 127 in a position between the tension spring and the thread container base.

When the shuttle has completed its loop taking movement and the limb of the needle thread loop has been carried intothe" slot'125 of the thread container, the cam 120will pass'over the cam follower pin 119 and-the coil spring 118 will return the rod 101 and with it the thread clamping finger 102 to the position illustrated in FIG. 2.

The parts carried in the shuttle body will thus return to the position illustrated in FIGS. 7 and 9 and one limb of the needle thread loop-will-be disposed through the

spaces

82 and 83 between'the flanges 80 and 81: of the thread containerbase andbetween thetension spring 94 and the thread container base. 1

FIG. 3-illustratesthe head end elevational view of the sewing-machine atthe completion of a cycle of operation.

Cit

- 6 It will be noted that the take-up arm 15' is at the top of its stroke having just set the last stitch in the sewing cycle and the thread cutter will have completed its operation after the last stitch has been set. in these respects the sewing machine is conventional. If the machine were to be started for another cycle with the thread in the same condition as at the completion of the previous cycle i.e., as illustrated in FIG. 3, the take-up in descending with the first needle penetration, would give up sufiicient thread for the formation of a needle thread loop for the shuttle, and the shuttle parts would be opened as described above to admit a limb of the needle thread loop, but the take-up in moving back to the top of its stroke after the first needle penetration would draw the thread completely out of the thread container the shuttle and no further stitching would be possible. In order to alleviate this condition and for the additional purposeof metering to the thread container the precise amount of thread necessary to sew whatever particular tack that is being prepared, a thread metering device actuated by the work clamp opening mechanism is provided.

The work clamp lifting mechanism which is conventional for machines of this type includes a clamp lifting bar 131 journaled vertically in the bracket arm of the machine. At the lower extremity of the bar 131 is fixed a strut 132 which underlies a pin- 133 extending from the upper jaw member 31 of the work clamp. A clamp lifting lever 134 fulcrumed on top of the bracket arm and adapted to be actuated by way of a pull chain 135 by any suitable treadle or knee press has one end underlying a collar 136 fast on the upper extremity of the clamp lifting bar 131.

The collar 136 is formed with a transverse aperture 137 which accommodates loosely a horizontal section 13-3 of a pull off lever indicated generally as 139. The aperture 137 defines the fulcrum for turning movement of the pull off lever, the horizontal section 138 being formed with a notch 140 entered by a set screw 141 threaded into the collar 136 to prevent endwise movement of the horizontal section 138 with respect to the collar. One limb 142 of the pull off lever extends downwardly and terminates in a thread accommodating loop 143 disposed between two thread guides 144 and 145 fixed on the front face of the end cover plate 146 of the bracket arm. The other limb 147 of the pull off lever extends lengthwise along the top of the bracket arm beneath the horizontal limb of a post 143 fixed in the bracket arm. A coil spring 14-9 between the post 148 and the limb 147 of the pull off lever biases the pull off lever clockwise and into the position illus'- trated in FIG. 1. A stop screu 150 threaded into the post 148 and bearing against the limb 147 of the pull off lever serves to turn the lever as illustrated in FIG. 5 when the v clamp lifting bar 131 is raised.

The pull off lever cooperates with the conventional needle thread nipping and tensioning devices of the sewing machine to meter the amountof needle thread which will i be deposited in the thread container ofthe shuttle. The conventional thread nipping. and tensioning devices of the machine include a threadnipping spring carried at the" lower extremity of the needle bar 16. A lever 156 ful crumed on the needle bar is engaged by an abutment (not shown) on the clamp lifting bar when the work clamp is opened and at that time only forces the nipping spring:

against the needle bar to clamp the needle'thread therebetween.- Thus; when the work clamp is opened and the pull off lever swings out, the thread drawn out by the pull off will not be drawn from the needle but will instead come from the thread supply. As best shown in FIG. l

. the'usualnee'dle thread tensioning device 15-? is provided with a conventional tension releasing push rod 158 which is operatively engaged by one arm of a bell crank 159 carried on the bracket armof themachine. A coil spring push rod 158 to be moved by the spring 160 to open or release the thread tension device 157.

The amount of thread pulled from the supply by the pull oft" lever 134 can be regulated by adjusting the position of the adjusting screw 150 and, for any particular shape and size of tack, the amount of thread for the under thread supply can be adjusted by this means with great nicety.

It will be understood that when the needle makes the first penetration of the work in any cycle of operation, the needle thread will extend continuously from a supply, through the needle thread tensioning devices, take up and thread guiding means, through the eye of the needle and through the thread container carried by the shuttle. As the needle emerges from the work after the first penetration, the take up arm 15 will rise to the top of its stroke, but instead of setting a stitch as it will do on each succeeding rise, the take up on its first rise will draw out of the thread container any excess thread carried down by the shuttle, leaving in the thread container only that amount previously drawn from the supply by the pull off lever 139. In order to insure that the take up arm will draw the excess thread from the thread container and not from the supply, a thread nipper 162 is carried on the bracket arm of the machine frame and is arranged with a spring plate 163 acted upon by the cam lugs 129 to nip the thread leading from the thread tension device to a supply of thread. The nipper 162 is arranged so as to be acted upon by a cam lug 120 only during the interval between the first and second needle penetration of each cycle.

FIGS. 4, 5, 6 and '7 illustrate the sequence of events during the first stroke of the needle in a stitching cycle. FIG. 4 illustrates the position and arrangement of parts at the end of a cycle of operation. The threads have been cut automatically. A short end of the needle thread extends from the eye of the needle and the short end of thread from the thread container in the shuttle has been withdrawn from the thread container by the action of the thread cutter.

Fig. 5 illustrates the position and arrangement of parts when the clamp is opened for removal and replacement of the work fabrics. The nipper 155 on the needle bar is closed and the pull off lever 139 has drawn out thread through the released needle thread tension device 157 and thence from the thread supply.

FIG. 6 illustrates the position and arrangement of parts as the shuttle together with the thread clamping finger 192 carries the loop of needle thread downwardly after the first needle penetration of the cycle. The rod 101 has moved forward and urged the thread container face plate 88 outwardly to present the slot 125 between the thread container face plate and base to the loop of thread on the shuttle. The take up arm has moved to the bottom of its stroke to give up the maximum length of thread to the shuttle.

FIG. 7 illustrates the position and arrangement of parts as the take up arm rises to the top of its stroke following the first penetration of the needle in the cycle. The rod 101 and thread clamping finger 102 have been retracted and the thread container face plate 88 has been reseated against the base of the thread container and the excess thread in the thread container is being drawn up by the rising take up arm.

On succeeding needle penetrations in the cycle of operation of the machine, the machine operates in the same manner as any conventional shuttle type lock stitch sewing machine, i.e. the needle thread loops drawn out by the shuttle are passed over the thread container and thereby looped with the thread limb which is retained in the thread container. At the end of the cycle, the impact of the,stop motion device operates the thread trimming mechanism to sever both the upper and under thread limbs of the lock stitch seam. The operation of the thread trimming mechanism also serves to draw out the tag end of thread from the thread container. This tag end of thread can be made to be as small as possible and yet still long enough to remain under the influence of the tension spring in the thread container until after the last stitch in the cycle has been formed by proper adjustment of the pull-0E adjusting screw 150. A stream of air may also be applied beneath the stitching point in any known manner to augment the removal of the tag end of the thread.

The advantages of the present invention are manifold. Foremost is the fact that tacks of true lock stitches may be produced indefinitely without manual replenishment of the usual bobbin of under thread mass. The possibility always present in conventional lock stitch machines, that the bobbin thread supply may become exhausted midway in a seam or tack thus ruining the perfection of the work, is obviated with this invention. The provision of a supply of under thread in this invention is accomplished in a completely automatic fashion; that is, no manual steps specifically for the purpose of supplying the under thread mass are required of the machine operator. While in the preferred embodiment of this invention, the opening of the work clamp by the operator is utilized to effect the operation of the thread pull-off which determines the amount of thread deposited in the shuttle thread container, it will be appreciated that opening of the work clamp would be necessary whether or not the present invention or a conventional bobbin type sewing machine were utilized. Furthermore, the thread pull-off may be actuated automatically if desired by any suitable cam connection elfective, for instance, during the first downstroke of the needle and before loop seizure by the shuttle.

The tack or seam produced by the sewing machine of this invention is superior to that of a conventional lock stitch sewing machine. In the sewing machine of the present invention, the under thread mass and the needle thread are continuous at the start of actual stitching, as illustrated in FIGS. 7 and 13. The resulting seam or tack, therefore, will have only two thread ends as compared with four thread ends which will be present if a conventional lock stitch machine is used.

While it is true that a tag end of thread must be discarded at the end of each tack with the sewing machine of this invention, this tag end may be made very small as explained above. The loss of thread as compared with a conventional lock stitch machine is far less, however, than the tag end of thread discarded after each tack. In a conventional lock stitch tack, as illustrated in FIG. 12, since there are loose thread ends at the beginning of the tack, provision must be made in each tack for several tying stitches at the beginning of the tack which tying stitches may be dispensed with in the sewing machine of this invention. After deducting from the tag end of thread discarded with each tack, the amount of thread saved by the elimination of tying stitches, the thread consumption of the machine of this invention compares very favorably with that of conventional lock stitch sewing machines.

Having thus set forth the nature of the invention, what we claim herein is:

1. A sewing machine having a thread carrying eyepointed needle, a throat plate having an aperture therein, mechanism for actuating said needle to cause its eyepointed portion to descend through said aperture, a needle loop-seizing member located in a position adjacent the throat plate to seize the loop from said needle when its eye-pointed end passes through the aperture in the throat plate, means for operating said needle loop-seizing member in timed relation with said needle in the formation of lock stitches, mechanism cooperating with said loop seizing member for securing on said loop-seizing member a loop of needle thread seized thereby, means for rendering said thread securing means elfective during loop seizure by said needle loop-seizing member, means for maintaining said thread securing means eifective during operation of said needle loop-seizing member in timed relation with said needle subsequent to loop seizure for draw- 9 ing a supply of needle thread through the eye of the needle and beneath the throat plate during the operation of said mechanism for actuating said needle, and means for storing said. threaddrawn through. the eye of the needle for use in forming lock stitches during subsequent stitch forming cycles.

2. A sewing machine having a thread carrying eyepointed needle, a threat. plate having an aperture therein, mechanism for actuating said needle to cause its eyepointed portion to descend through said aperture, a needle loop-seizing member and located in a. position adjacent the throat plate to seize the loop from said needle when its eye-pointed end passes through the aperture in the throat plate, means for operating said loop-seizing member in timed relation with said needle to seize and manipulate thread loops from said needle in the formation of lock stitches, needle thread gripping mechanism for securing on said loop seizing member a loop of needle thread seized thereby, means for operating said thread gripping mechanism during loop seizure by said loop seizing member, means for shifting said thread gripping mechanism in timed relation with said loop seizing member for drawing a supply of needle thread through the eye of the needle and holding it in a position adjacent the loop seizing member so that it may be used to form lock stitches and means for automatically actuating said operating and shifting means for said needle thread gripping mechanism during operation of the mechanism for actuating said needle.

3. A sewing machine having a frame including a work support and an eye-pointed thread-carrying needle disposed at one side of said work support, mechanism for actuating said needle to cause its eye-pointed end to move through anaperture in the work support to a position on the other side of said work support, a needle loopseizing member located on the opposite side of said work support to said. needle, means permanently connecting said needle and loop seizing member to cause them to operate in timed relation in the formation of lock stitches, mechanism cooperating with said loop-seizing member to positively secure on said loop seizing member a loop of thread seized thereby drawing a supply of needle thread through the eye of said needle to a position adjacent the loop seizing. member, means for holding said supply of thread for use in forming lock stitches during further operations of the needle and loop seizing member, means driven in timed relation with said needle bar actuating mechanism for opening said thread holding means and simultaneously rendering effective said means for securing on said loop-seizing member aloop of thread seized thereby, and means driven in timed relation with said needle bar actuating mechanism for closing said thread holding means and simultaneously rendering ineffective said means for securing on said loop-seizing member a loop of thread seized thereby.

4. A cyclically operated lock stitch sewing machine comprising a thread carrying needle, a movable loop taker cooperating with said needle in the formation of lock stitches, thread measuring means operable between said needle and a supply of needle thread to draw, from a supply the length'of thread required to produce a predetermined number of stitches, means associated with said sewing machine and automatically operable to draw said length of thread provided by said thread measuring means through the eye. of. the needle and deposit it in said loop taker, and means in said loop taker to manipulate said length of. threadwhereby lock stitches. can be produced using said length of thread as the locking thread.

5. In a lock stitch sewing machine having a work support, a needle carried. at one side of said work support and. having an eye for receiving a needle thread, means for actuating saidneedle to impart an uninterrupted series ofneedle penetrations of a. work fabric on said work support, thread tensioning means'at the opposite side of said work support for frictionally engaging a locking thread,

, and means automatically operated by said sewing machine and a loop taker adapted to carry a loop of needle thread from the eye of the needle completely about said thread tensioning means, the improvement which comprises, means automatically operated by said sewing machine and effective during one of said uninterrupted series of needle penetrations for opening said thread tensioning means for admittance thereto by one limb of a needle thread loop being carried by said loop taker, a clamp means eifective simultaneously with said last mentioned means to secure in place on the loop taker a needle thread loop being carried thereby, and means automatically operated by said sewing machine for closing said thread tensioning means and releasing said clamp means after said needle thread limb has been deposited in said thread tensioning means.

6. In a lock stitch sewing machine having a work support, a needle carried at one side of said work-support and having an eye for receiving a needle thread, means for imparting an uninterrupted series of endwise needle penetrations of a work fabric to be stitched, and a loop taker having means to house a supply of locking thread, means to apply a tension to the thread so housed, and means tocarry a loop of needle thread completely about the supply of thread housed by the loop taker, all in the conventional process of lock stitch formation, the improvement which comprises, means automatically operated by said sewing machine and effectively during one of said uninterrupted series of needle penetrations for opening the thread housing means of said loop taker for admittance of one limb of a needle thread being carried by said loop takervto said thread tensioning means, a clamp means effective simultaneously with said last mentioned means to secure in place on the loop taker a needle thread loop being carried thereby, and means automatically operated by said sewing machine for closing said thread housing means and releasing said clamp means after said needle thread limb hasv been admitted to said thread tensioning means.

7. In a lock stitch sewing machine having a work support, a needle carried at one side of said work support and having an eye for receiving a needle thread, means for reciprocating said needle endwise to penetrate a work fabric to be stitched, and a loop taker having means to apply a tension to a locking thread, and means to carry a loop of needle thread completely about said locking thread tensioning means, all in the conventional process of. lock stitch. formation, the improvement which comprises needle thread clamping means associated with said loop taker,.said means being automatically operated by said sewing. machine and eifective on a predetermined one of an uninterrupted series of needle penetrations to aug-' merit said loop taker in the carrying of an abnormally large loop of needle thread, means automatically operfor rendering said needle thread loop clamping means ineffective and'for closing said threadtensioning means after said needle thread limb has been deposited therein;

and before the nextsncceeding penetration of said needle.

8. in a cyclically operated lock stitch. sewing machine having a work support, a needle carried at one side of said work support and having an eye for receiving a needle thread, means forimpartinga predetermined and; uninterrupted number of endwise penetrating reciprocational process of lock stitchformation, the improvement,

which. comprises, means automatically operated by saidsewing machine and effective on the first needle penetration of each cycle of sewing machine operation for opening the thread tensioning means of said loop taker for admittance thereto of one limb of a needle thread being carried by said loop taker, a clamp means eflective on the first needle penetration of each cycle of sewing machine operation to secure in place on the loop taker a needle thread loop being carried thereby, and means automatically operated by said sewing machine for closing said thread tensioning means of said loop taker after said needle thread limb has been deposited therein and before the next succeeding penetration of said needle.

9. In a cyclically operated lock stitch sewing machine having a thread carrying needle, means for imparting a predetermined and uninterrupted number of endwise work penetrating movements to said needle, a loop taker having thread housing means adapted to house a supply of thread, means to apply a tension to the thread so housed, and means to carry a loop of needle thread completely about the supply of thread housed by the loop taker, all in the conventional process of lock stitch formation, and a thread trimming mechanism operative at the conclusion of each cycle of sewing machine operation to sever the threads of the lock stitch seam adjacent the work, the improvement which comprises, means automatically operated by said sewing machine and elfective during each cycle of sewing machine operation for clamping to said loop taker the loop of needle thread carried thereby, means automatically operated by said sewing machine during the operation of said last mentioned means and effective to open the thread housing means and the thread tensioning means of said loop taker for admittance of one limb of the needle thread loop being carried by said loop taker, and means automatically operated by said sewing machine for rendering both said needle thread loop clamping means and said thread tensioning and thread housing opening means ineffective after said needle thread limb has been deposited in said thread tensioning device.

10. In a lock stitch sewing machine having a thread carrying needle, means for imparting an uninterrupted series of endwise needle reciprocations to penetrate a work fabric to be stitched, a loop taker having means adapted to house a supply of thread, means to apply a tension to the thread so housed, and means to carry a loop of needle thread completely about the supply of thread housed by the loop taker, and needle thread control means including a needle thread tensioning device and a needle thread take-up device operative on the needle thread between the needle and the needle thread tensioning device, the improvement which comprises, a thread pull-off device operable to draw out a supply of needle thread between said needle thread tensioning device and said needle prior to a predetermined one of said uninterrupted series of needle penetrations, means automatically operated by said sewing machine and effective on said predetermined needle penetration for opening the thread housing means and the thread tensioning means of said loop taker for admittance thereto of one limb of a needle thread being carried by said loop taker, and means automatically operated by said sewing machine for closing said thread housing means and said thread tensioning means of said loop taker after said needle thread limb has been deposited therein and before the next succeeding penetration of said needle.

ll. In a cyclically operated lock stitch sewing machine having a thread carrying needle, means for imparting a predetermined and uninterrupted number of endwise work penetrating reciprocations to said needle in each cycle of operation of said sewing machine, a loop taker having means to house a supply of thread, means to apply a tension to the thread so housed, and means to carry a loop of needle thread completely about the supply of thread housed by the loop taker, and needle thread control means including a needle thread tensioning device and a needle thread take-up device operative on the needle thread between the needle and the needle thread tensioning device, the improvement which comprises, a thread pull-olf device operable to draw out a supply of needle thread between said needle thread tensioning device and said needle, means for actuating said thread pull-elf device prior to the first of said predetermined and uninterrupted number of endwise work penetrating reciprocations of said needle, means automatically operated by said sewing machine and elfective on the first needle penetration of each cycle of sewing machine operation for opening the thread housing means and the thread tensioning means of said loop taker for admittance thereto of one limb of a needle thread being carried by said loop taker, and means automatically operated by said sewing machine for closing said thread housing means and said thread tensioning means of said loop taker after said needle thread limb has been deposited therein and before the next succeeding penetration of said needle.

12. A loop taker for a lock stitch sewing machine comprising a circularly movable loop taker body, a thread engaging beak formed on said loop taker body, a thread container journaled in said loop taker body for relative turning movement therebetween, said thread container including two nested portions, means slidably joining said nested thread container portions for relative movement substantially parallel to the axis of turning movement of the thread container relative to the loop taker body, thus permitting said nested portions to be axially separated, a thread tensioning spring carried by one of said thread container portions and disposed to bear against the other of said thread container portions, and means limiting the motion of said thread tensioning spring away from the thread container portion on which it is carried so that when the thread container portions are axially separated a thread receiving space will be opened between the thread tensioning spring and the thread container portion against which the spring is disposed to bear.

13. A loop taker for a lock stitch sewing machine comprising a loop taker body adapted to be moved circularly during stitch formation, a thread engaging beak formed on said loop taker, a two-part thread container adapted to be constrained from circular movement during stitch formation, said thread container including a base part and a cover part formed to define a thread space therebetween, means for journaling said thread container base in said loop taker body for relative turning movement therebetween, means for supporting said thread container cover for movement toward and away from said thread container base, spring means biasing said thread container parts toward one another, means accessible exteriorly of said loop taker for shifting said thread container parts apart, and a thread tensioning spring supported for limited flexing movement by one of said thread container parts and disposed within said thread space therebetween to bear against the other of said thread container parts when said thread container parts are biased together.

14. A lock stitch forming stitching mechanism for use in a cyclic sewing machine having a stop motion mechanism, a work holding clamp including a clamp opening mechanism, cam means operatively connected to trip said stop motion mechanism after a predetermined number of stitches and a thread cutting mechanism operative to sever the sewing threads at the completion of each cycle of stitching operations, said stitching mechanism comprising, an endwise reciprocatory threaded needle, a needle thread take-up, a needle thread nipper arranged between the take-up and a supply of needle thread, a thread pull'ofi device arranged to operate on the needle thread between the thread nipper and the needle, means operatively connecting said thread pull-oil device for operation in response to actuation of said work clamp opening mechanism, a loop taker disposed to cooperate with said needle to engage, draw out and release loops of needle thread, thread tensioning means carried by said loop taker, means associated with said thread tensioning means and accessible exteriorly of said loop taker for opening said thread tensioning means to admit one limb of a loop of needle thread being drawn out by said loop taker, and thread tension opening mechanism carried by saidIseWing; machine and including a linkage extending between, said: accessible thread tension opening means and said sewing machine cam means, said cam means being formed to actuate said tension opening linkage and said needle, thread nipper during only the first needle penetration of each cycle of sewing machine operation.

15, In, alock stitch sewing machine having a thread carrying needle, means for imparting endwise work penetrating movement to said needle and a movable loop takercooperating with said needle in the formation of lock stitches, said loop taker including a beak arranged to seize a loop of thread from the needle and a body portion from which said beak extends and about which the beak is adapted to draw the seized needle thread loop, means operatively associated with said loop taker and adapted, to augment said loop taker in drawing out an abnormally large loop of needle thread, said means comprising a finger carried by said sewing machine, means for positively interlocking said finger for movement with said loop taker and also shiftably supporting said finger for movement toward and away from said loop taker body portion, and means effective during operation of the sewing machine for shifting said finger toward said loop taker body portion to grip between said finger and said loop taker. body portion one limb of a loop of needle thread being drawn, out by said loop taker beak.

116. In a lock stitch sewing machine having a thread carrying needle, means for imparting endwise work penetrating movement to said needle, and a circularly movable loop taker cooperating with said needle in the formation of lock stitches, said loop taker including a beak arranged to seize a loop of thread from the needle and a body portion from which said beak extends and about which the beak is adapted to draw the seized needle thread loop, means operatively associated with said loop taker and adapted to augment said loop taker in drawing out an abnormally large loop of, needle thread, said means comprising a circularly movable finger having an axis of circular movement coincident with that of said loop taker, means for imparting the same circular movements to both said finger and said loop taker, means supporting said finger for axial movement'toward and away from said loop taker body portion, and means effective during operation of said sewing machine for shifting said finger toward said loop taker body portion to grip therebetween one limb of a loop of thread being drawn out by said loop-taker beak.

17. In a lock stitch sewing machine having a thread carrying needle, means for imparting endwise work penetrating movement to said needle, a circularly movable loop taker cooperating with said needle in the formation of lock stitches, said loop taker comprising a body portion and a thread engaging beak formed on said body portion, a thread container journaled in said loop taker body portion, means constraining said thread container from circular movement during stitch formation, a thread tensioning device carried in said thread container, and means operatively associated with said loop taker effective to deposit a length of needle thread in said thread tensioning device, said means comprising a finger carried by said sewing machine for circular movement with said loop taker, said finger also being shiftably supported for movement toward and away from said loop taker body portion, means effective during operation of said sewing machine for shifting said finger toward said loop taker body portion to grip therebetween one limb of a needle thread loop drawn out by said loop taker beak, and means associated with said sewing machine and movable with said finger toward and away from said loop taker body portion, said means disposed when shifted toward said loop taker body to open said thread container for admission of said gripped loop of needle thread to said thread tensioning device.v

1.8. In a lock stitchsewing; machine having a thread carrying needle and a circularly moving loop taker cooperating with said needle in the formation of lock stitches, said loop taker comprising a body portion, a thread engaging beak formed on said body portion, a two part thread container adapted to be constrained from circular movement during stitch formation, said thread container including a base part and a cover part formed to define a thread space therebetween, means for journaling said thread container base in said loop taker body for relative'turni-ng movement therebetween, means for supporting said thread container cover for movement toward and away from said thread container base, spring means biasing said thread container parts toward one another, means accessible exteriorly of said loop taker for separating, said thread container parts, and a thread tensioning spring supported for limited flexing movement by one of said thread container parts and disposed within said thread space therebetween to bear against the other of said thread container parts when said thread container parts are biased together, and means cooperating with said loop taker. and effective to position a length of needle thread between said thread tensioning spring and the thread container part against which said spring bears, said means comprising a member carried by said sewing machine for circular movement with said loop taker and also supported for movement toward and away from said loop taker body portion, means effective to shift said member into a position against both said loop taker body portion and said exteriorly accessible. means for separat ing sai thread container parts, thus to grip a needle thread loop on the loop taker body portion and to open the thread container for admission of said needle thread loop to the thread tensioning'spring.

19. In a cyclically operated lock stitch sewingmachine:

having a thread carrying needle, a loop taker, means supporting said loop taker for stitch forming movement in cooperation with-said needle in the formation of lock stitches, cam means driven by said sewing machine, stop motion mechanism controlled by said cam means to stop said sewingmachine upon completion of a predetermined number of stitches, a thread tensioning device carried by said loop taker, means for opening said thread tensioning device for admission of a, thread thereto, a thread clamping means carried for movement with the loop taker in the stitch forming movements thereof, means for shifting said thread clamping means into engagement with said loop taker to clamp a loop of needle thread on said loop taker, and means associated with said sewing machine and automatically operated by said cam means during each cycle of sewing machine operation for simulta neously actuating said thread clamping means and said means for opening said thread tensioning deviceto deposit a needle thread loop taken by said loop taker into said thread tensioning device. 7

20. In a cyclically operated lock stitch sewing machine having a thread carrying needle, a circularly movable loop taker cooperating with said needle in the formation of lock stitches, cam means driven by said sewing machine, stop motion mechanism controlled by said cam means to stop said sewing machine upon completion of a predetermined number of stitches, a hollow drive shaft journaled in said sewing machine, means operatively connecting said loop taker to said drive shaft, a rod slidable axially within said hollow drive shaft, means keying said rod for circular movement with said drive shaft, a thread gripping member carried by said rod and disposed when said rod is shifted toward said loop taker to grip therebetween a limb of needle thread loop on the loop taker, a thread container carried by said loop taker, and having a retracted position within said loop taker and an extended position with respect to said loop taker, spring means biasing said thread container into said retracted position in which position a thread loop on the loop taker moves freely over the thread container, means carried by said thread container and accessible exteriorly of said loop taker for shifting said thread container into said extended position in which position a thread loop on the loop taker will move into said thread container, said exteriorly accessible means being disposed for engagement and actuation by said rod when said rod is shifted toward said loop taker, and cam follower means actuated by said cam means for shifting said rod toward said loop taker during a portion of the predetermined number of stitches in each cycle of sewing machine operation.

21. In a lock stitch sewing machine having an endwise reciprocatory threaded needle, means for directing a needle thread from a supply to said needle, a loop taker, a loop-seizing beak formed on said loop taker, means for storing a locking thread in said loop taker, and actuating mechanism for operating said needle and said loop taker in timed relation for imparting during each needle reciprocation a needle loop-seizing motion of said loop-seizing beak and motion of said loop taker to concatenate and set into a work fabric lock stitches of said needle and locking threads, the combination comprising, a thread cutting means for severing said needle thread closely adjacent to said work fabric, means for operating said thread cutting means when said needle and said loop taker occupy stitch setting position, needle thread gripping means carried for motion in timed relation with said loop taker, and means automatically operative for rendering said needle thread gripping means effective during the needle loop-seizing motion of said loop-seizing beak on the needle reciprocation next succeeding the operation of said thread cutting means to secure on said loop taker a thread loop seized by said loop-seizing beak to augment the loop taker in drawing from the needle thread supply an abnormal length of needle thread for use as looking thread on succeeding needle reciprocations.

22. in a lock stitch sewing machine having a thread carrying eye-pointed needle, a work fabric supporting throat plate having an aperture therein, mechanism for reciprocating said needle endwise to cause its eye pointed portion to penetrate a work fabric on said throat plate and descend through said aperture, a needle thread 100p seizing member operating in timed relation with said needle and located in a position adjacent to the throat plate to seize the thread loop from said needle when its eye-pointed end passes through the aperture in the throat plate, the combination comprising a thread cutting means for severing the needle thread between the needle and the work fabric, means for operating said thread cutting means when said needle is raised out of the work fabric, means operating together with said thread loop seizing member for securing on said loop-seizing member a loop of needle thread seized thereby, means for rendering said thread securing means automatically eifective upon loop seizure by said loop-seizing member during the needle penetration next succeeding the operation of said thread cutting means for drawing a supply of needle thread through the eye of the needle, and beneath said throat plate and means for storing said thread drawn through the eye of the needle for use in forming lock stitches during subsequent stitch forming cycles.

23. A cyclically operated lock stitch sewing machine comprising an eye-pointed thread-carrying needle, a movable loop taker cooperating with said needle in the formation of lock stitches, means for supporting a supply of thread relatively to said sewing machine, a thread tensioning device associated with said sewing machine, a thread take-up means carried on said sewing machine and operated in timed relation with said needle, means for directing a thread from said supply through said thread tensioning device, through said thread take-up means and through the eye of said needle, thread measuring means operable to draw from said supply and through said thread tensioning device toward said needle a length of thread required to produce a predetermined number of stitches, means associated with said sewing machine and automatically operable to draw said length of thread provided by said thread measuring means through the eye of the needle and deposit it in said loop taker, and means in said loop taker to manipulate said length of thread whereby lock stitches can be produced using said length of thread as the locking thread.

References Cited in the file of this patent UNITED STATES PATENTS 1,093,241 Barron Apr. 14, 1914 1,115,663 Gray Nov. 3, 1914 1,118,450 Sibbald Nov. 24, 1914 1,794,255 Stephenson Feb. 24, 1931 2,354,559 Thornton July 25, 1944