US3099972A - Bobbin thread replenishing mechanism for lock stitch sewing machine - Google Patents

Description

g- 6, 1963 R. E. JOHNSON ETA]. 3,099,972

BOBBIN THREAD REPLENISHING MECHANISM FOR LOCK STITCH SEWING MACHINE Filed Dec. 11, 1961 3 Sheets-Sheet 1 k0 Q w ,8 flu x N A a no 0 Y; 0 L0 N g m x y I.

g D I 'I5I\;:V L 0%: g, INVENTORS. g 0 RALPH E. JOHNSON and 5 BY FRANK J. BARTOSZ WITNESS IL :0"

WgL L ATTORJVE'Y 1963 R. E. JOHNSON ETAL 3,099,972

BOBBIN THREAD REPLENISHING MECHANISM FOR LOCK STITCH SEWINGMACHINE Filed Dec. 11, 1961 I 5' Sheets-Sheet 2 v IDNVENTORS. RALPH E JOHNSON and .BY FRANK J. BARTOSZ WITNESS A g. 6, 1963 R. E. JOHNSON ETAL 3,099,972

BOBBIN THREAD REPLENISHING MECHANISM FOR LOCK STITCH SEWING MACHINE 3 Sheets-Sheet 3 Filed Dec. 11, 1961 INVENTORS. RALPH E. JOHNSON and y FRANK J. BARTOSZ United States Patent F 3,099,972 BOBBIN THREAD REPLENISEWG MECHANISM FOR LOCK STITCH SEWING MACHINE Ralph E. Johnson, Boonton, and Frank I. Bartosz, Cranford, N.J., assignors to The Singer Company, a corporation of New Jersey Filed Dec. 11, 1961, Ser. No. 158,451 8 Claims. (Cl. 112-181) This invention relates to lock stitch sewing machines of the type employing a loop taker rotatable in one direction and referred to in the art as a rotary hook, and more particularly, to a novel and improved mechanism for replenishing the thread on a bobbin in place in a rotary hook.

It is an object of this invention to provide a novel and improved mechanism for replenishing the thread on a bobbin in place in a rotary hook during that interrelated motion of the needle and rotary hook as is required for the formation of lock stitches.

Another object of this invention is to provide a bobbin thread replenishing mechanism of the above character employing stitch forming instrurnentalities for producing lock stitches in the conventional manner and in which the means for effecting replenishment of the bobbin in place in the loop taker is physically separate from the stitch forming instrumentalities and remains both during bobbin replenishment and conventional stitch formation out of physical engagement with any elements of the stitch forming instrumentalities or the actuating mechanism thereof.

With the above and other objects and advantages in view, as will hereinafter appear, this invention comprises the devices, 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 with a portion of the bed broken away more clearly to illustrate this invention applied thereto,

FIG. 2 represents an enlarged end elevational view of the bed portion of the sewing machine of FIG. 1,

FIG. 3 represents an enlarged bottom plan view of the thread severing device of this invention including the operating bracket arm carried on the pivoted bed extension,

FIG. 4 represents an enlarged end elevational view of the loop taker including fragments of the throat plate, presser foot, needle, and the thread deflector of the bobbin replenishing mechanism, and illustrates the arrangement of parts and of the thread upon the initial 100p seizure at commencement of bobbin replenishment,

FIG. 5 represents a view similar to FIG. 4 illustrating the position of parts and of the thread substantially at cast off of the initial loop seizure at the commencement of bobbin replenishment,

FIG. 6 represents a view similar to FIG. 4 illustrating the position of parts and of the thread during seizure by the loop taker beak of the second loop after commencement of bobbin replenishment,

FIG. 7 represents a view similar to FIG. 4 illustrating, the position of parts and of the thread substantially at cast off of the second loop seized by the loop taker after commencement of bobbin replenishment,

FIG. 8 represents a view similar to FIG. 4 illustrating 3,099,972 Patented Aug. 6, 1963 the position of parts and of the thread upon completion of bobbin replenishment and in readiness for the formation of lock stitches, and

FIG. 9 is a cross sectional view of the loop taker including fragments of the thread deflector and thread severing knife taken substantially along line 9-9 of FIG. 8.

Referring to the drawings, this invention may be embodied in a conventional lock stitch sewing machine having a bed 11, a standard 12, and a bracket arm 13: overhanging the bed. A needle 14 endwise reciprocable in the bracket arm is connected for cooperating interrelated motion required for the formation of lock stitches with a. loop taker indicated generally at 15 in the bed by means of a main shaft 16 in the bracket arm, a standard shaft 17, connected to the main shaft by gears 18, and a bed shaft 19 connected to the standard shaft by gears 20 and having the loop taker secured thereto. Any conventional work feeding mechanism may be employed, as for instance, a drop feed mechanism including a feed dog 21 operating through a throat plate 22 on the bed, which throat plate is also apertured as at 23 to accommodate the needle. The bed may be provided with a bed extension 24 pivoted as at 25 to the bed.

As illustrated in FIG. 1, the needle thread is directed from a supply spool 25 to the needle 14 by suitable guides and through a main tensioning device 28 of which all are conventional. The thread from the needle eye to the supply spool will be hereinafter referred to as T while that limb of the needle thread extending from the needle to the free extremity will be referred to as T The free extremity of thread T; in preparation for bobbin replenishment may be secured in a thread nipper 29 carried on the presser bar 30 to which the conventional presser foot 31 is supported.

Referring to FIGS. 2 and 4 to 9, the loop taker 15 preferably takes the form of a rotary hook including a cup shaped body portion 40 formed with a loop seizing beak 4-1. The body portion is formed with an internal raceway 42 complemented by a gib 43 to constrain therein a bearing rib 44 of a bobbin case 45. The gib is formed with a thread detaining tail 46.

The bobbin case 45 is formed with a center post 47 which is shouldered as at 48 to accommodate a sleeve 49 of frictioning material such as nylon or other flexible synthetic plastic material. A bobbin 50 having flanges 51 and 52 is journaled on the sleeve 49 for turning movement resisted only by the friction imposed by the sleeve 49. The center post 47 of the bobbin case is transversely slotted as at 53 to accommodate an inturned lug 54 formed on a rotation restraining bracket 55 formed with an upwardly extending finger 56 disposed between spaced abutment springs 57-57 secured beneath the throat plate 22. The rotation restraining bracket 55 is maintained on the center post by the frictional engagement of the inturned lug 54 with the sleeve 49.

As thus far described, the rotary hook is capable of concatenating loops of thread seized from the needle by the 'beak 41 completely about the :bobbin case and, of course, about the bobbin jour-naled therein so as to form lock stitches (Federal stitch type 301) when a locking or bobbin thread is present on the bobbin. This stitch forming process is of a conventional nature in which the seized needle thread loop enters between the loop taker 3 a body portion 40 and the bobbin case wthrough registering gaps in the raceway 42 and bearing rib 44, caught against the so-called ingoing pocket, that is, one edge 58 of the bearing rib 44 adjacent to the gap therein and thus divided into two limbs. The thread is then directed one limb between the bobbin case and the loop taker and the other limb over the face of the bobbin and bobbin case, while the gaps move out of registry. Finally the thread is drawn out of the loop taker and up the finger 53 when the gaps again overlap.

For replenishing thread on the bobbin, this invention provides, as illustrated in FIGS. 1 and 2, a thread deflecting member 60 formed with a pair of obliquely inturned fingers 61 and 62. The member 60 is secured by a screw 63 to a plunger 64 slidable in a boss '65 in the bed with the fingers 61 and 62 disposed axially opposite the space between the bobbin case 45 and the periphery of the bobbin flange 51. The plunger 64 is formed with a head 66 con-straining on the plunger and against the bed a compression spring 67 which serves to bias the thread deflecting fingers 60 and 61 into the space between the bobbin flange and the bobbin case and within the space between the planes containing the bobbin flanges 51 and 52 as illustrated in dotted lines in FIG. 9.

Pivoted at 68 in the bed is a bell crank having an arm 69 engaging the plunger head 66 and an arm 70 carrying a follower pin 71. A cam bracket 72 secured beneath the bed extension plate 24 by screws 73 is tormed with a cam finger 74 underlying the follower pin 71 and arranged so as to release the bell crank 70 when the bed extension plate 24 is raised as illustrated in solid lines in FIG. 1 allowing the spring 67 to urge the thread deflecting fingers opposite the space between the bobbin flanges, and arranged so as to turn the bell crank 69, 70 in a clockwise direction as viewed in FIG. 1 when the bed extension is turned down into coplanar relation with the bed 11 to force the plunger outwardly in opposition to the spring 67 and thus shift the thread deflecting fingers entirely outwardly beyond the face of the bobbin flange 51 as illustrated in solid lines in FIG. 9.

FIGS. 4 to 7 illustrate the manner in which the machine operates to replenish bobbin thread when the bed extension plate 24 is raised. FIG. 4 illustrates the position of the parts and of the needle thread shortly after initial loop seizure at commencement of bobbin replenishment. The thread loop will next be caught in the ingoing pocket 58, divided and carried one limb across the back and the other limb about the front of the bobbin case as illustrated in FIG. 5. The thread deflecting fingers 60 and 61, however, being shifted to a position between the bobbin flanges will deflect the limb passing over the exposed face of the bobbin case inwardly and into the bobbin as illustrated in FIG. 5.

The second needle penetration after commencement of bobbin replenishment, as illustrated in FIG. 6, will occur with a loop of needle thread detained about the bobbin. That limb of the thread on the bobbin which extends to the needle eye will pass behind a thread engaging finger -80 formed on the bobbin case and as the loop seizing beak traverses that thread limb, which incidentally passes about the tail 46 of the gib, the second loop of needle thread drawn out by the loop seizing beak will extend between the needle and the thread engaging finger 80. This second loop of thread will be caught in the ingoing pocket 58 and as shown in FIG. 7 and the divided loop will be carried one limb behind and the other limb about the front face of the bobbin case. The thread deflecting fingers 60 and 61 will, as before, deflect that limb passing over the exposed face of the bobbin case inwardly and into the bobbin. As the thread loop illustrated in FIG. 7 is drawn oif the loop taker, that portion caught in the thread engaging finger 80 having passed about the back of the bobbin case will be drawn olf the thread engaging finger 80 and the thread will appear as in FIG. 6 except that two successive loops of thread will be disposed on the bobbin. The thread replenishing process can thus continue until any desired number of successive loops of thread have been deflected onto the bobbin Within the capacity of the bobbin.

To terminate bobbin replenishment, it is only necessary that the operator turn the bed extension 24 down into coplanar relation with the bed 11 as illustrated in dashed lines in FIG. 1. The cam finger 74 will then urge the cam follower pin 71 upwardly, turning the lever 69, 70 clock-wise as viewed in FIG. l and thereby urging the thread deflecting member outwardly against the action of the compression spring 67 so as to position the thread deflecting fingers '61 and 62 outwardly beyond the bobbin case and beyond the bobbin flange 5 1 as illustrated in solid lines in FIG. 9. On succeeding needle penetrations, therefore, the loop taker will concatenate seized loops of needle thread in the conventional manner completely about the bobbin and bobbin case so as to form locked loops of needle and bobbin threads in the formation of lock stitches.

At the conclusion of bobbin replenishment two limbs of thread T and T will extend from the bobbin and upwardly through the needle aperture 23 and it is necessary that one of the limbs preferably T; be severed adjacent to the bobbin so that during subsequent stitching the thread on the bobbin .can be drawn off as it is consumed in the seam.

The thread severing mechanism as illustrated in FIGS. 2 and 3, comprises a bracket secured beneath the bed and on which is pivoted as at 911 a knife supporting lever 92 having secured at its free extremity a knife blade 93 disposed axially opposite the body portion '40 of the loop taker. The knife supporting lever is biased by means of a wire spring 94 which bears against a pin 95 on the lever 92 into a retracted position against a stop provided by the head of a stop screw 96 in the bracket 90. The retracted position of the lever 92 as illustrated in solid lines in FIG. 3 corresponds to the position of the blade 93 spaced outwardly beyond the bobbin case as illustrated in solid lines in FIG.

Fulcrumed on the pin 95 is a U-shaped lever 97 slidably embracing the knife supporting lever and biased by means of a wire spring 98 toward a position in which the base of U-shaped lever 97 strikes the knife supporting lever 92. The U-shaped lever 97 carries a depending pin 99 by which the knife is shifted inwardly to sever the limb T of the thread on the bobbin.

A bracket 100 secured by screws 101 to the bed extension 24 carries an upstanding pin 102 which moves, when: the bed extension is turned, in a path which intersects the pin 99 on the lever 97 when the lever 97 is biased against the knife supporting lever 92.

When the bed extension is shifted from an upturned to a coplanar relation with the bed, the pin 102 in engaging the pin 99 will shift the knife carrying lever 92 inwardly carrying the knife blade 93 toward the loop taker and into the position illustrated in dashed lines in FIGS. 3 and 9 which as illustrated in FIG. 8 traverses the path of the thread limb T and severs that thread limb.

The pin 102 in engaging the pin 99 will turn the knife supporting lever 92 about the pivot pin 91 and the pin 99 in moving in an' are about the pin 91 will be turned out of the path of the pin 102 thus permitting the bed extension 24 to be turned into planar relation with the bed 11 and also permitting the spring 94 to return the knife 93- outwardly beyond the loop taker. When the bed extension 24 is next turned into an upstanding position, the pin 102 will contact the pin 99 and turn the U-shaped lever 97 against the action of the wire spring 98 until the arouate motion of the U-shaped lever 97 about the pin 95 moves the pin 99 out of the path of the pin 102 thus allowing the bed extension to be turned up without disturbing the position of the knife supporting arm 92 relatively to the head of the stop screw 96. i

The sewing machine described hereinabove thus provides means for replenishing thread on the bobbin in place in the rotary hook during that interrelated motion of the needle and hook as is required for the formation of lock stitches. The machine will replenish bobbin thread whenever and so long as the bed extension 24 is raised and upon lowering of the bed extension will sever the anchor limb of thread on the bobbin and automatically revert to lock stitch formation.

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

1. In a sewing machine having a work penetrating thread carrying needle, a needle thread take-up member, a rotary hook, a thread engaging beak on said rotary hook, an annular internal raceway formed in said rotary hook, a bobbin case, an annular bearing element on said bobbin case journaled in said rotary book raceway, means for restraining said bobbin case from rotation with said rotary hook, said rotary hook raceway and said bobbin case bearing element each being formed with a gap, said gaps being disposed in registry in the needle loop seizing position of said thread engaging beak, a thread accommodating bobbin formed with axially spaced flanges and journaled in said bobbin case, and actuating means for operating said needle, rotary hook, and take-up mechanism in timed relation for seizure of loops of needle thread by said beak, manipulation of said seized thread loops through said registering raceway and bearing member gaps and about said bobbin case by said rotary hook, and shedding of said manipulated thread loop from said beak by said take-up member as is required in the formation of lock stitches, means for winding thread carried by said needle onto said bobbin comprising a thread deflecting finger, means supporting said finger on said sewing machine externally of said rotary hook, means for shifting said thread deflecting finger into an effective position extending opposite the space between said flanges of the bobbin journaled in said bobbin case to deflect onto said bobbin thread loops shed from said beak, and means for maintaining said thread deflecting finger in said effective position during a plurality of successive work penetrations of said needle.

2. In a lock stitch sewing machine having a reciprocating thread carrying needle, a loop-taker, a thread accommodating bobbin carried within said loop-taker, and actuating mechanism operatively connecting said needle and said loop-taker for cooperative movement in timed relation as is required for the seizure and manipulation by said loop taker of successive loops of thread from said needle, means for constraining said bobbin within said loop-taker completely within the path of a thread loop manipulated by said loop-taker, means supported externally of said loop-taker for deflecting successive loops of thread being manipulated by said loop-taker onto said bobbin while said bobbin is under the influence of said constraining means, means for sewing lock stitches using thread deflected onto said bobbin by said deflecting means comprising, means for rendering said deflecting means inefiective, and means for effecting termination of one limb of the last thread loop deflected onto said bobbin at a point substantially within said loop taker.

3. In a sewing machine having a work penetrating thread carrying needle, a needle thread take-up member, a rotary hook journaled in said sewing machine, a thread engaging beak on said rotary book, an annular internal raceway formed in said rotary hook, a bobbin case, an annular bearing element on said bobbin case journaled in said rotary hook raceway, means for restraining said bobbin case from rotation with said rotary hook, said rotary hook raceway being formed with a gap into which said thread engaging beak extends, said bobbin case bearing element being formed with a gap disposed in registry with said gap in said rotary hook raceway in the needle loop seizing position of said thread engaging beak, a thread accommodating bobbin formed with axially spaced flanges and journaled in said bobbin case, and actuating means for operating said needle, rotary hook, and take-up mechanism in timed relation for seizure of loops of needle thread by said beak, the manipulation of said seized thread loops through said registering raceway and bearing member gaps and about said bobbin case by said rotary hook, and shedding of said manipulated thread loop from said beak by said take-up member as is required in the formation of lock stitches, means for winding thread carried by said needle onto said bobbin comprising a plunger axially slidable in said sewing machine along an axis substantially parallel to that of said rotary hook, a thread deflector carried by said plunger, a thread deflecting finger formed on said thread deflector and disposed outwardly beyond the periphery of said bobbin flanges, operator influenced means for shifting said plunger axially to position said thread deflecting finger into and out of an effective position extending opposite the space between said flanges of the bobbin journaled in said bobbin case to deflect onto said bobbin thread loops shed from said beak, and means for maintaining said thread deflecting finger in said effective position during a plurality of successive work penetrations of said needle.

4. In a sewing machine as set forth in claim 3, a thread engaging finger formed on said bobbin case and projecting into said gap in said bobbin case bearing element from that side of said gap toward which said thread engaging beak moves during rotation for engaging that limb of a thread loop deflected onto said bobbin which extends to and which is carried by the needle into the path of the thread engaging beak of the rotary hook while said thread deflecting finger is maintained in said effective position.

5. In a sewing machine as set forth in claim 3, a thread severing knife, means supporting said thread severing knife for movement in a path intersecting one limb of a loop of thread shed from said thread engaging beak and deflected onto said bobbin, and means operated by said operator influenced means for shifting said knife into severing engagement with said thread limb when said thread deflecting finger is shifted out of effective position.

6. A sewing machine as set forth in claim 3, in which said operator influenced means comprises a work support extension, means pivotally supporting said work support extension on said sewing machine for operator influenced movement into and out of an effective work supporting position, and means carried by said work support extension for shifting said plunger to position said thread deflecting finger into an effective position when said work supporting extension is moved out of an effective work supporting position.

7. A sewing machine as set forth in claim 3 in which said operator influenced means comprises a work support extension, means pivotally supporting said work support extension on said sewing machine for operator influenced movement into and out of an effective work supporting position, and means carried by said work support extension for shifting said plunger to position said thread deflecting finger into an effective position when said work supporting extension is moved out of an eflective work supporting position, a thread severing knife means, means pivotally supporting said thread severing knife means relatively to said sewing machine on an axis substantially perpendicular to that defined by said means pivotally supporting said work support extension for movement of said thread severing knife means in a path intersecting one limb of a loop of thread shed from said thread engaging beak and deflected onto said bobbin, means biasing said thread severing knife in a retracted position out of engagement with said limb of said thread loop, a knife actuating drive pin carried by said work support extension and disposed substantially perpendicular to the axis defined by said means pivotally supporting said work support extension, a knife actuating driven pin carried by said thread severing knife means and disposed substantially parallel to the axis defined by said means pivotally supporting said thread severing knife means, said drive pin being disposed relatively to said driven pin for operative engagement therewith for shifting said thread severing knife into severing relation with one limb of a loop of thread shed from said thread engaging beak and deflected onto said bobbin during operator influenced motion of said work support extension from uneffective to eifective work supporting position.

8. A sewing machine as set forth in claim 7 in which a pivotal support means .is provided for securing the driven pin to the thread severing knife means about an axis 10 substantially parallel to that defined by the means for pivotally supporting the thread severing knife means rela- .tively to the sewing machine, and in which interengaging stop means are provided between said thread severing knife means and saidpivotal support means for said driven pin for locking said driven pin relatively to said thread severing knife means only during operative'engagement of said 'drive pin with said driven pin during operator influenced motion of said work support extensions from uneffective to efiective Work supporting position.

References Cited in the file of this patent UNITED STATES PATENTS 1,794,255 Stephenson Feb. 24, 1931 FOREIGN PATENTS 1,224,744 France Feb. 8, 1960

Claims (1)

1. IN A SEWING MACHINE HAVING A WORK PENETRATING THREAD CARRYING NEEDLE, A NEEDLE THREAD TAKE-UP MEMBER, A ROTARY HOOK, A THREAD ENGAGING BEAK ON SAID ROTARY HOOK, AN ANNULAR INTERNAL RACEWAY FORMED IN SAID ROTARY HOOK, A BOBBIN CASE, AN ANNULAR BEARING ELEMENT ON SAID BOBBIN CASE JOURNALED IN SAID ROTARY HOOK RACEWAY, MEANS FOR RESTRAINING SAID BOBBIN CASE FROM ROTATION WITH SAID ROTARY HOOK, SAID ROTARY HOOK RACEWAY AND SAID BOBBIN CASE BEARING ELEMENT EACH BEING FORMED WITH A GAP, SAID GAPS BEING DISPOSED IN REGISTRY IN THE NEEDLE LOOP SEIZING POSITION OF SAID THREAD ENGAGING BEAK, A THREAD ACCOMMODATING BOBBIN FORMED WITH AXIALLY SPACED FLANGES AND JOURNALED IN SAID BOBBIN CASE, AND ACTUATING MEANS FOR OPERATING SAID NEEDLE, ROTARY HOOK, AND TAKE-UP MECHANISM IN TIMED RELATION FOR SEIZURE OF LOOPS OF NEEDLE THREAD BY SAID BEAK, MANIPULATION OF SAID SEIZED THREAD LOOPS THROUGH SAID REGISTERING RACEWAY AND BEARING MEMBER GAPS AND ABOUT SAID BOBBIN CASE BY SAID ROTARY HOOK, AND SHEDDING OF SAID MANIPULATED THREAD LOOP FROM SAID BEAK BY SAID TAKE-UP MEMBER AS IS REQUIRED IN THE FORMATION OF LOCK STITCHES, MEANS FOR WINDING THREAD CARRIED BY SAID NEEDLE ONTO SAID BOBBIN COMPRISING A THREAD DEFLECTING FINGER, MEANS SUPPORTING SAID FINGER ON SAID SEWING MACHINE EXTERNALLY OF SAID ROTARY HOOK, MEANS FOR SHIFTING SAID THREAD DEFLECTING FINGER INTO AN EFFECTIVE POSITION EXTENDING OPPOSITE THE SPACE BETWEEN SAID FLANGES OF THE BOBBIN JOURNALED IN SAID BOBBIN CASE TO DEFLECT ONTO SAID BOBBIN THREAD LOOPS SHED FROM SAID BEAK, AND MEANS FOR MAINTAINING SAID THREAD DEFLECTING FINGER IN SAID EFFECTIVE POSITION DURING A PLURALITY OF SUCCESSIVE WORK PENETRATIONS OF SAID NEEDLE.

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