US1706872A - Presser-foot-lifting mechanism for sewing machines - Google Patents

Description

F. -M. cARbf March 26, 1929.

PRESSER FOOT LIFTING MECHANISM FOR SEWING MACHINES Filed Dec. 16, 1927 a INVENTOR fiederic )1. 6 am WITNESSES ATTORNEY Patented Mar. 26, 1929.

v UNITED, STATES PATENT OFFICE.

FREDERIG CARD, OF BRIDGEPORT, CONNECTICUT, ASSIG'NOR TO THE SINGER MANU- FACTURING COMPANY, OF ELIZABETH, NEW JERSEY, A COR JERSEY.

.. URATION OF NE'lV Application filed December 16, 1927. Serial No. 240,383.

This invention relates to improvements in automatic presser-ltoot httmg mechanisms for sewing machines and has forits object to provide a simple construction of this character, capable 01" being readily applied to a sewing machine in commercial use and of being readily thrown intoand out of operation. at will during the operation of the machine. 7

While, in principle, the presentpressen foot lifting mechanism may evidently be readily embodied in sewing machines generally,.it was more particularly desi ned for use .in the con'imercially well-known zigzag stitch sewing machinedisclosed, for instance, in the U. S. patent to G. M. Eames and J. S. Finch, No.1,196,534, August 29, 1916.

In its preferred embodin'ient, the improved construction comprises a lifter-lever :lulcrumed intermediate its ends upon the machine frame, one arm of the lever being positioned to engage the usual projecting arm oI the presser-barlifter sleeve and the other arm of the lever carrying a roller adapted, in the operative position of the lever, to be engaged by acam mounted upon the usual needle-vibrating shaft of the machine. The two arms of the lever are connected by the links of a toggle-joint of which" the knuckle may be conveniently shifted in'one direction to rigidly lockthe lcverarms against relative movement in operative position or in an opposite direction to swing the lever arms about their common fulcrum into inopera tive position. The fulcrum-point oi the lever coincides withthe point of pivotal connection of said lever arms and also coincides with the fulcrum-point oi the regular treadle-controlled lifter lever for the presserbar, While the actuatingcam of the present lifter-lever replaces the usual collar upon the projecting end of the needle-vibrating shaft. It will therefore be apparent that the pres ent improvement may be readilyapplied to any sewing machine of the class specified without any material alteration of the regular parts 01 the machine.

In the accompanying drawings, Fig. 1 is a rear side elevation, partly in section, of

a sewing machine to which the present im provement has been applied. Fig. 2is a sectional view substantially onthe line2-2 of Fig. 1. Fig. 3 is a sectional. yiew substantially on the line 3-3 of Fig. 1. Fig. 4 is a perspective view oi a portion of the presser-bar lil'ter sleeve and of the end of the lever engaging an arm of said sleeve.

Referrin g to the drawings, the sewing machine forwhich the present lIllPL'OVGHlGIlh was more particularly designed comprises a base 1, from which projects the forwardly extending work-supporting arm 2. Rising from the base 1 is the usual tubular standard of the overhanging bracket-arm 4., terminating in the head 5.

Journaled in the lnackeharm a is the r0 tary main shaft (3, carrying at one end the driving pulley '2" and operatively connected atijts opposite end, in the usual manner, with the needle-bar 8,,carrying the needle 9, (shown in dotted lines only in Fig. 1), to impart vertical reciprocations to saidneedlc. The needle-bar 8 is journaled for endwisc reciprocation in suitable bearings provided in the frame 10 mounted to swing or vibrate about the pivot-pin 11. The lower end of the swinging frame 10 is suitably joined to the forward end of the connectingarod 12, of which the opposite end is provided with the -fork l3 strathllingthe cam 14 upon the transverse shat-t l5, suitably journaled in the bracket-arm at. l he cam-shaft 15 carries the worm-wheel 16 driven bythe Worm 17 upon the main shaft 6, the proportions of the worm and worm-wheel being such that the main-shaft 6. rotates twice for each revolution of the cam-shaft. V

The connecting rod 12 is, as usual, pivotally connected with one end of the link 18 of which theopposite end is fulcruined upon the crank-arm 19 fixed upon the inner end of the shaft 20 journaled in suitable bearings provided in the bracket-arm 4. To the outerend of said shaft-2O is suitably secured the adjusting ar1n21 of which "the free end may be adjustably lined in any selected positionlengthwise of the segmental slot 22 provided in the bracket 23 upon the arm 1. Preferably the movement otthe arm 21, in one direction, is limited by an adjustable screw 24 upon the bracket 23. It will be understood that adjustment of the arm 21 with respectto' the slot 22 movesthe shaft 20 to thereby shift the fulcrum point of the link 18 alli'orded by the crank-arm 19. It will. also be understood that changes in the position of the fulcrum-point oi": the link 18 cf resser-bar. As usual, the arm 28 is adapted to be engaged by the hand lifter-lever 31,

whilethearm 29 is positioned to be engaged by a treadle operated lever.

The machine as hereinbefore described is Commercially well known in the art and it otal supportupona shouldered pivot-beer I threaded into the bracket-arm 4t, it be ng an.

istherefore deemed unessential' to enter into greater detail in the description of its structural features.

Referring now 'more particularly to the present improvement in this machine, provision is madefor at will automatically lifting the presser-foot above the work during theoperation of the machine. The meclmnism provided for this purpose compr' two arms 32 and 33 having a coincident derstood that the arms 32 and are free to swing about their common pivotal simport with'respect to each other. The forward end of the arm 32 adjustably carries a lifter element 35 constituting onemember of an angle-bracket of which the other-member 36 is provided with vertically al ned, elongated slots,jas 37, entered by guideserews, as 38, threaded. mto the arm 32. The bracketmember 36, at its upper end, has a lateral ear I 39 into which is threaded an adp stmg-scrmv 4o lOjournaledin an apertured ear 41 formed on'the arm 32. The lifter element 35 un derlies the arn1'29 of thepresser-bar lifter sleeve andcarries an adjustable screw l2 adapted to bear upon a shelf43 regularly provided upon the bracket-arm head 5 to thereby limit th'e'downward movement of the free end of the arm'32. i

Upon the free end of'the arm 33 is journalcd a fiangedroller l engaged by a cam '45 having its hub 46 fixed upon the projectin end of the shaft '15 said cam 15 reolaeingthecollar heretofore employed in this machine for holding the shaft 15 against cndwis'ejmo'vement in itsbearin'gsf It will be'observedthat'the cam has two active portions terminatmg 1n the spaced nubs l7,

whereby during the operation ofthe machine the free end of-the arm 33 is depressor twice for'each'rotation of the shaft, i. e.,. once for each complete'endwise reciprocation of the needle.

, Means are-provided for securingllie arnzs i 1 32 and'33, in operativeposition, against relative angular movement, whereby said arms together constitute a lifterdever functioning during the opcrati on of the machine to transmit lifting movements to the Presser-bar 25, the lever-arm securing means being of a character whereby during the operation of the machine the angular relationship of the arms 32 and 33 with respect to each other may be at will changed to render the lever inoperatnie. To this end, one member 48 of alink-togg c is pivoted by a screw all) upon the arm connected with the member 48 by means of a pivot screw 50 is the other member or link 51 of the toggle, said member 51 being pivotally connected by means of a pivot-screw to a lateral extension 52, of the arm 33. For cmivenimitly shifting the toggle-knuckle constituted by the pivotscrew 50, to thereby alter the angular relationship of the arms 32 and 33, the member 48 is extendoiil beyond the knuckle to provide the linger-piece 5t depending below the bracket-awn t, whereby said lingcr-picce is readily acce ale to a machine operator. Furthermore, the member 4-8 is provided at opposite sides of the toggle-knuckle with laterally projecting stop-ears and 56 in position to be alternately engaged by the link 51 to limit the movement of said togglcknuckle in opposite directions.

It will be observed that the pivot-bolt 34- also constitutes the fulcrum of the usual treadle operated lifter-lever 57, of which the laterally extending end 58 also underlies the arm 20 of the lifter sleeve. 'lhemfore to apply the present improvement to the commercial machine herein described in general, it is only necessary to substitute the pivotbolt for the lifter-lever fulcrum screw usually employed and to substitute the cam 45 for the regular shaft-collar. \Vhcn the lifter device is applied to the machine and it is desired to intermittently lift the ln'esser-bar agninstv the action of its usual depressing spring (not shown), the linger-piece 54 is manipulated to shift the toggle into the full lineposition shown in Fig. 1, with the link 51 engaging the stop-car 56. In this position,'th e roller 44 is disposed in engagement with they cam 15 thereby transmitting intermittent lifting movements to the presser-bar through the lever- arms 32 and 33 rigidly maintained in definite angular relationshi by the toggle described. When the togge is shifted into the dotted line position shown in Fig. 1, the forward end of the arm 32 drops slightly, or until the stop-screw 42 engages the shelf 13. The arm 32 being held against further movement, the change in the angular relationship of the arms 32 and 33, caused by the shifting of the toggle-knuckle, withdraws the roller 44 from engagement with the cam 45 to render the lifter device inoperative.

Having thus set forth the nature of the invention, what I claim. herein is 2- .1. A presser-bar lifting mechanism for sewing machines, including a lever comprising pivotally connected arms adapted to be rigidly maintained in a definite angular relationship, an actuating member adapted to operatively engage one of the arms of said lever, a lifter-member associated with the resser-bar of the machine adapted to be engaged by the other arm of said lever, and means for at will during the operation of the machine changing the relative angular position of said arms to render said lever inoperative to lift said presser-bar.

2. A resser-bar lifting mechanism for sewing machines, including a lever compri ing pivotally connected arms adapted to be rigidly maintained in a definite angular relationship, a pivotal support for said lever coinciding with the pivotal connection of the lever-arms, an actuating member adapted to operatively engage one of the arms o1. said lever, a lifter-member associated with the presser-bar of the machine adapted to be engaged by the other arm of said lever, and means for at will during the operation oi the machine changing the relative angular position of said arms to render said lever inoperative to lift said presser-bar.

3. A presser-bar lifting mechanism for sewing machines, including a lever comprising pivotally connected arms, a toggle-jointconnection between said. arms, an actuating member adapted to operatively engage one of the arms of said lever, and alitter-member associated with the presser-har of the machine adapted to be engaged by the other arm oi? said lever.

i. A resser-bar lifting mechanism for sewing machines, including a lever comprising pivotally connected arms, a toggle-joint connection between said arms, means for limiting the extent of movement oi the "toggle-joint knuckle, a lifter-member associated with the resser-bar of the machine means for at will during the operation of the machine shifting the knuckle of said toggle-joint tochange the relative angular relationship of said lever arms.

6. A presser-bar lifting mechanism for sewing machines, including a lever comprising pivotally connected arms, a toggle-joint connection between. said arms, one of the linlemembers of said toggle-joint being ex tended to provide convenient means to shift the knuckle of said joint, a lifter-member associated with the presserbar of the machine, a bracket adjustably secured upon one of the arms of said lever adapted to operatively engage said lifter-member, and a rotary cam adapted to operatively engage the other arm of said lever.

7. A presser-bar lifting mechanism for sewing machines, including a lever comprising pivotally connected arms adapted to be rigidly maintained-in a definite angular re lationship, a pivotal support for said lever coinciding with the pivotal connection of the leve1:'-arms, an actuating cam adapted to operatively engage one of the arms of said lever, a liiltermember associated with the pressenbar of the machine adapted to be engaged by the other arm of said lever, and a manually actuated presser-bar lifter-lever fulcrrnned upon the pivotal support of the warn-actuated lever.

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

FREDERIC M. CARD.

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