US2541888A

US2541888A - Speed-responsive presser device for sewing machines

Info

Publication number: US2541888A
Application number: US19063A
Authority: US
Inventors: Berthold P Pinkvoss
Original assignee: Singer Co
Current assignee: Singer Co
Priority date: 1948-04-05
Filing date: 1948-04-05
Publication date: 1951-02-13
Anticipated expiration: 1968-02-13
Also published as: AT171048B; GB639515A; DE822190C; CH272215A; FR973373A

Description

Feb. 13, 1951 B. P. PINKVOSS 2,541,888

SPEED-RESPONSIVE PRESSER DEVICE FOR SEWING MACHINES Filed April 5, 1948 3 Sheetg-Sheet 1 P. PINKVOSS SPEED-RESPONSIVE PRESSER DEVICE FOR SEWING MACHINES Feb. 13, 1951 3 Sheets-Sheet 2 Filed April 5, 1948 Feb. 13, 1951 B. P. PINKVOSS 2,541,888

SPEED-RESPONSIVE PRESSER DEVICE FOR SEWING MACHINES Filed April 5, 1948 3 Sheets-Sheet 3 I Unvenlifl erl w fipz'nvoss WwneM" z Patented Feb. 13, 1951 SPEED-RESPONSIVE PRESSER DEVICE FOR SEWING MACHINES Berthold P. Pinkvoss, Stratford, Conn, assignor to The Singer Manufacturing Company, Elizabeth. N. L, a corporation of New Jersey Application April5, 1948, Serial ,No. 19.063

15 Claims, (01412-235) to sewing machines and i ntion relates theremore particularly to presser mechanisms for..- It is recognized, in the sewing machine .art, t a the speed of operation of -a sewing machine is a factonas to the amount of pressure required to be placed upon the pressz r-ioot of a sewing wmachine to cause it to hold the work in contact with the throat-plate and feed-dog, and to effect :accnrate feeding of thework. This is particular- ;lywtrue sewing machines provided with the .soz calle d alternating presser mechanisms which include "two Presser-test so connected together that the pressure of the .one on the work reacts to lift the other. In presser mechanisms of this q nature, it is common practice to give to one presserioot, frequently ,called the 'walking 1foot, work-engaging and work-releasing move- ;ments and feed-and-return movements in synlchronism with the similar movements of a fourmotioned ted-dog which engages the under side pf the work, whereby the work is-gripped between the two eeding eleIn-entsand positively advanced. The -non-feeding presser-foot is caused to bear .u-pon-the work,--to holdthe work stationary on the throat-plate while the feeding pregsser-foot is titted, and to be raised above the work by the pressure of the feeding foot on the work. Thus the two presser feet alternately engage and re- ;lease the work. One .or more springs are .com-

snaonly employed to dpress the presser-feet upon the work-to .cause the feeding toot to assist --.the feed-dog :in feeding the work and to cause the non-feeding presser-foot to clamp the work f the h oat r ate duri g the time the -n:.edle l the w rk; a. b r eni tro e of th detains-e e ents. 1 a

It ha be n fou d, that whe u ing n mal spring pressure .on alternating press;r mechaf nisms, :thatbecau-se of-the inertia .of theparts, etjqn, and the inability. of the presser spring l Itorreact snffioiently .o.1;iic,k 1y when operating at -bi gh s peeds,the,priissnfet w u d not b a u o .the work -.but would gradually be raised higher higher until the feeding foot would, in offcct, paw the .air above the work with the re- ,su lt that the work was not properly vclamped ;and fed thereby. "llhis .difiiculty was overcome, "gto' a1 g extent, by greatly increasing the spring t ng-able enact ofp erloading t mach n and-of requ ring exces iv work y th It rato t ife h rn ssl ei et or inser io d removal .of the work. It also produced the undesirable o sav ge th ve to b wed by th the prg'esserl-ieet which, however, had

feeding-foot when the machine was operating at relatively slow speeds This invention has as a primary objectv to overcome the defects and undesirable features of prior constructions of this nature.

Another object 'of- .the invention is to provide an alternating presser m chanism which will securely hold the work on the throat-plate, be-

tween successive feeding strokes of the feeding device; which will efiect positive and accurate fading of the work underall speeds ofoperation;

and which will prevent overloading of the machine an c ring of the work under slow speed operation.

These objects have been attained by providing a presser mechanism which exerts a relatively light pressuraon the presser-foot when the ma- ;chine is operated at relatively slow speeds and which automatically increases the pressure proportion to increases inspeed.

With the above and other objects in vie-W1, as will hereinafter appear, the invention comprises the devices, combinations and arrangcmentsof parts hereinafter set forth and illustrated in the accompanying drawings of a preferred embodiment of the invention, from which the .SEVQraI features vof the invention and the advantages attained thereby will be readily understood by those skillld in the art.

In .the drawings,

Fig. 1 is a side elevation, partly broken away and partly in section, .of a sewing machine embodying the present invention; the machine b.6- ingillustrated as at rest.

Fig. 2 is -a left .end .elevation, partly broken away, of the machine illustrated in Fig. 1. o

Fig. 3 is an enlarged sectional View of the midportion of Fig. l with certainof the parts in the positions they assume under high speed operation.

Fig. 4 is an enlarged transverse sectional view taken substantially .on the line 5-4 of Fig. .1.

Fig. 5 is an enlarged transverse sectional view taken ,substantially on the line 5-5 of Fig. ,L

Fig. 6 is a detail sectional view, taken on the line .6 ii of Fig. 2, showing the means for .ponfnecting the pr.sser spring with the alternating presser mechanism.

- means for connecting the alternating presser-bar lifting lever to the supporting bar of the nonfeeding presser-foot.

Referring more specifically to the drawings, the invention is disclosed as embodied in asew- I9 of a three-armed lever l9. j I! and the feeding presser-foot carried thereby ing machine comprising a frame including a work-supporting plate i, a standard 2 secured to and rising from the plate I. Formed integrally with the standard is an overhanging bracketarm 3 which terminates, at its free end, in a bracket-arm h ad 4, journaled lengthwise within the bracket-arm is a main or needle-bar driving shaft 5 which carries, at its rear end, a combined belt and hand wheel 6 having a belt groove 1 adapted to receive a driving belt (not shown), by means of which the shaft may be driven from any suitable source of power. Reci rocably mounted in bearings 8 and 9 in the bracket-arm head 4 is a needle-bar l carrying, at its lower end, a thread-carrying eye-pointed needle H adapted to cooperate with a suitable loop-taker (not shown) in the formation of stitches. The needle-bar is reciprocated from a crank-disk l2, secured on the shaft 5, by conventional means de- ,signated generally as at.

The machine is also provided with an alternating presser mechanism including a presser-bar l3, mounted for vertical reciprocation in the bracket-arm head 4, and carrying at its lower end a non-feeding presser-foot l4 adapted to 'hold the work on the usual throat-plate l carried by the work-supportng plate I. Cooperating with the presser-foot I4 is a combined presserand work-feeding-foot l6 which cooperates with the feed-dog f of a conventional four-motioned work-feeding mechanism. The foot I6 is secured upon the lower end of a feed-bar I1 the upper end of which is fulcrumed, at l8, to one arm The feed-bar are given rising-and-fall ng and feed-and-return movements from

eccentrics

20 and 2|, respectively. secured upon the main shaft 5. The eccentric 20 is surrounded by the strap end 22 of adown- .wardly and rearwardly inclined pitman 22 the other end of which is pivotally connected to the i upper free end of a feedift rock arm 23 clamped .upon a sleeve 24 journaled at one end in the bracket-arm head 4 and at its other end in a bracket 25 secured to and depending from the under side of the bracket-arm 3. The outer end of the sleeve 24 carr es an upright arm 26 which is connected, by a link 21, to the upstanding arm I9 of the three-armed lever l9. The third arm [9, of the lever I9, is connected by an anchor link 2'! to a pin 28 secured in the bracket-arm head 4. A vertically disposed link 29 is pivotally connected, by the stud 30 with the third arm l9 of the lever l9. with a collar 3| secured by pinch joint 32 on the upper end of the presserbar l3. From the foregoing it w ll be understood that rotation of the shaft 5 and the eccentric 20 thereon will cause the link 19 to be osci lated back and forth about the pivot screw l8 and stud thereby alternately raising and lowering the presser-bar l3 and feed-bar l1. Back and forth feed-and-return movements are given to feed-bar i! from the eccentric 2i on the shaft 5 by means now to be described. A

downwardly and rearwardly inclined pitman 33 has its upper strap end surrounding the eccentric 2| and its lower end pivotally connected with the upper free end of a rock-arm 34 secured upon 4 the rear end of a feed-drive rock shaft 35 journaled within the sleeve 24.

At its forward end the feed-drive rock-shaft 35 has secured to it the hub end of a depending feed-drive rock-arm 36, the lower end of which ispivotally connected, at 31, to one end of a link 38 the other end of which is pivotally conthis nature, rocking of the three-armed lever I9 clockwise as seen in Fig. 2, depresses the foot l6 into contact with the work. When further downward movement of the foot is prevented further movement of the lever in the same direction causes the lever to turn about the fulcrum and thereby lift the presser-foot I4 clear of the work. In this position of the parts the feedingfoot 16 is given its rearward feeding stroke in synchronism with the feeding stroke of thefeeddog 1. After the feeding stroke is completed the lever I9 is oscillated in the opposite direction thereby depressing the foot l4 upon the work and lifting the feeding foot Hi to permit it to be returned to its forward position.

The presser-feet l4 and 16 are normally depressed upon the work by a leaf spring 40, supported at its rear end on a bracket 4! secured to the under side of the bracket-arm 3, as shown most c'early in Fig. 5. The forward end of the spring 40 extends into the bracket-arm head 4 and is connected, by a bolt 42, (see Fig. 6) with a stud 43 carried by the three-armed lever l9, which, as hereinbefore explained is connected with both the presser-bar l3 and the feed-bar I'l. Intermediate its ends, the spring 49 is engaged .by a shoe 44 which is pressed downwardly, to tension the spring 40. by its engagement with the lower unthreaded end 45 of a screw stud 45. This stud is threaded nto a bushing 46, which, in turn, is threaded into the lower wall of the bracket-arm 3. The upper end of the stud is provided with a screw driver slot whereby the stud may be rotated to adjust it axially, thereby to shift the shoe 44 vertica ly to vary the downward pressure exerted by the spring 40 on the presser-bars. This pressure will remain constant for any given adiustment of the stud 45. Preferably the stud 45 will be adjusted to produce a downward pressure onthe presser-feet which is most suitable for relatively slow speed operation of the sewing machine.

This invention has provided automatic means for varying the total downward pressure transmitted to the presser-feet l4 and I6 in proportion to the speed of operation of the machine. Th s means comprises an auxiilary spring device which acts in conjunction with the main spring device 40 to increase the spring pressure as the speed of the machine is increased. The auxiliary spring device includes a lever 41 preferably, but not necessarily, in the form of a second leaf spring located between thespring 40 and the bracketarm 3. The forward end portion of the spring extends into the bracket-arm head 4 and bears u on the spring 40, as shown most clearly in Fig. l. The rear end of the lever 41 is bifurcated, and straddles the inverted T-shaped lower end 48 of a twisted link 48, the upper end of which is pivotally connected at 49 to one arm 50 of a bell-crank lever 50, journaled on a stud 5| supported by the bracket-arm. Intermediate its ends the spring lever 41 is in contact with the lower emi or thebushing 46; hereir'ibefore' mention-ea worth ness: certain 1 conditions, serves": as a; fulfortfl springifli ThisbuShiligiS so located arranged that a in: the lowermost position of lime-48; as shciwninFig'. '1, the spring 41 is substantially tension-free and therefore transmits littleinifany; pres-sure to the spring Amupper" ar'm -50 ofthebell-crank lever 50 has a rheadmortion 50 located'between andengaging anannularflange-52 forming apart of 'a-sleeve l SWslidinglymounted onthe shaft 5; and a-thrust bear ng 53 mounted on: thesleeve 52.

, Secured up'orr the shaftd asbyset screws '54; is a: collar fi having airs-of spaced and oppositely extendiiigearstfip 51'betweenwhich are mounted, on:

pivot pins 58, 59," angle levers 6|.- In ardly extending arms so and fil ofthe levers 50- and 6 I,- res-pectively; engages; thrust ring 52 surrbund-ing the-shaft 5 The" other armsof the levers 60; 6-l-carryweights 63-a-nd 64; respectively.

Slidinglymounted in-the co lar 55=are four'thrust -pins' 65-whch are engaged, atone end, bythe thrust ring 62.- T-heopposi-te ends ofthe pins -65 Eiea'r'upomoneend ofthe sliding sleeve 52; A I

doil spring 66,.surroundingthe shaft 5 and'in .terposedbetween the 'flange 52 at the rear end of the sl-eevefiland -a'driving pu ley'6 l secured Assamihg' that the screw st'u'd l5 hasbeen adn tocauserther alternating pres er mechinsm: to function properly at a limited range of f relatively slow speeds, the bushing 46 1s adiusted the posit on inustfatedm Fig; 5'. The pressure or'mesprin-g ts n thejsl dingsle'eve 52 tempor ari holds the sleeve 52, pm:- 65 and thru t ring to give tome-main leaf spring 40 sufficient" I6 aficerltainl amount of resiliency therein-whiohwill prevent abrupt changes in pressure transmitted to the presser-feet. The extent to which the weights: 63 will be swungv outwardly andtherefore:the-amountv of pressure which the spring lever: 41 will transmit to the leaf spring. 40 will be proportional to the speed of rotation of the main shaft 5'.- Under maximum speed of rotation of the: main shaft the

weights

63, 64 and levers 60, 61 will. assume the positions shown in Fig 3;

and the full pressure'of both the leaf spring andthe" spring lever 41 will be transmitted to the presser-feet' Hand l6. H

From the foregoing, it will be perceived-that this invention has provided simple means forautomatica-llytransmitting to the alternating.

presser-feet downward pressure in amount required to effect the most efficient operation thereof under. all speeds of. operation of the sewing machine, from slow speed to maximum speed.-

Having thusset forth the nature of the invention, what Lclaim herein is: V

Ii Ina sewing maohine,v in combination, a work=support; a variable speed rotary shaft; a presser mechanism yieldingly biased downwardly toward said work-support;- and mechanismactuated bysaidshaft and-rendered effective at iner ed'sifie'ed ofrotation'has been atta ned'and the centrifugal force exerted on the levers is siiffic enttoovercomethe'pr'essure of the spring 6611 The range of" speeds from Zero no to" the:

spec a't n cn thecentrifugal force on'th'e levers fist?) overcome the'pres's'ure'of'the spring-"6B corresponds to thera'rige' orsped's undertfie'mainspring 40" wi1l exert a sumcient pressureloi'ithe Dresser-feet l4 and Hi to causethefiitoffifietion'properly. After the predetermined accelerated speedhas been attained, a further increase in speed will cause the weighted depressing the forward end of the lever and adding to the downward pressure exerted on the presser-feet by the leaf spring 40. Inasmuch as the lever "is made of spring metal there will be 1 The leve'r' 41 'ruicru'ms aboutthe unadersieeor the riead'ae orthe bushing '46 thereby creasing speeds of rotation thereof for amplifying the: downward pressure exerted by said presser mechanism, v

2.*In.- a sewing machine,- in combination; a

frame; a variable speed rotary shaft jou-rnaled in-said frame; a presser mechanism supported by. the frame; a-m-ember pivotally supported by said-frame and connected with said presser mechanism; and-means-actuated by said shaft and responsive to the variations in speed thereof for turning said member about its pivot to cause it to. transmit varying downward pressures'to said presser' mechanism.-

3. In a sewing machine, in combination a frame; a variable speed rotary shaft journaled in'said frame;- a presser mechanism supported by the frame; *a' lever fulcrumed intermediate its ends on said frame, one end of said lever being connected with said presser mechanism;- and speed responsive means-connected to the other end of said lever and actuated by said shaft-for turning said-lever about its fulcrum tocause it to transmit downward pressure on said presser mechanism in proportion to thexspeed of rotation ofsaidshafti 4'; In asewing machine, in combination,- a variable speed rotary shaft; a presser-foot; spring means exerting a downward pressure onsaid press'er-foot; and auxiliary means actuated by said shaft-=- and responsive to variations in the speed thereof forlamplifying the pressure exerted by -said-spring m-eans'in direct proportiontothe 7 proportion to the increase in speed of said rotary shaft.

'1. In a sewing machine, in combination, a rotary shaft; an alternating presser mechanism including a first presser-foot having vertical movements only and a second presser-foot having vertical movements and horizontal feed and return movements; spring means normally transmitting to said presser mechanism a predetermined downward pressure; and auxiliary means actuated by said shaft and rendered effective when the speed of rotation of said shaft reaches a predetermined rate for amplifying the pressure transmitted to said presser mechanism by said sprin means.

8. In a sewing machine, in combination, a variable, speed rotary shaft; an alternating presser mechanism including a first presser-foot having vertical movements only and a second presserfoot having vertical movements and horizontal feed and return movements; spring means normally transmitting to said presser mechanism a predetermined downward pressure; and auxiliary means actuated by said shaft and rendered effective when the speed of rotation of said shaft reaches a predetermined rate for variably amplifying the pressure transmitted to said presser mechanism by said spring means in proportion to increases in the speed of rotation of said shaft.

9. In a sewing machine, in combination, a variable speed rotary shaft; an alternating presser mechanism including a first presser-foot havin vertical movements only and a second presserfoot having vertical movements and horizontal feed and return movements; sprin means normally transmitting to said presser mechanism a predetermined downward pressure; and auxiliary means actuated by said shaft when the shaft has attained a predetermined speed of rotation for amplifying the pressure transmitted to said presser mechanism by said sprin means.

10. In a sewing machine, in a combination, a variable speed rotary shaft; a presser mechanism; means exerting a substantially constant downward pressure on said presser mechanism; a pair of speed-responsive elements carried by said shaft; and means actuated by said speedresponsive elements for transmitting to said presser mechanism additional downward pressure in amounts proportional to the speed of rotation of said shaft.

11. In a sewing machine, in combination, a variable speed rotary shaft; a presser mechanism; spring means exerting a substantially constant downward pressure on said presser mechanism; a pair of bell-crank levers carried by and rotatable with said shaft; a weight carried by one arm of each of said levers, said levers being arranged to be swung about their fulcrums by the centrifugal force exerted by said weights; and means actuated by the other arms of said levers for transmitting to said presser mechanism additional downward pressure in amounts proportional to the speed of rotation of said shaft.

12. In a sewing machine, in combination; a variable speed rotary shaft; a presser mechanism; spring means exerting a substantially constant downward pressure on said presser mechanism; a pair of speed-responsive elements carried by said shaft; a sleeve slidingly mounted on said shaft; means actuated by said speed-responsive elements for shifting said sleeve axially of said shaft; and means actuated by the sliding movement of said sleeve for transmitting to said presser mechanism additional downward pressure in amounts proportional to the speed of rotation of said shaft.

13. In a sewing machine, in combination, a. frame; a variable speed rotary shaft; a presser mechani m; means exerting a substantially constant downward pressure on said presser mechanism; a collar fixed to said shaft; a pair of speedresponsi e elements carried by said collar;'a lever fulcrumed on said frame; a member slidingly mounted on said shaft and engaging said lever; means actuat d by said speed-responsive elements for shifting said member lengthwise of said shaft to turn said lever about its fulcrum; and means actuated by the turning movement of said lever for ex rt ng additional downward'pressu e on said esser mechanism in amounts proportional to the speed of rotation of said shaft.

14. In a sewing machine, in combination, a frame; a variab e speed rotary shaft; a presser mechanism; means exerting a substantially constant downward pressure on said presser mechanism; a collar fixed to said shaft; a pair of speedres'ponsive elements carried by said collar; alever fulcrumed on said frame; a member slidingly mounted on said shaft and engaging said lever; means actuated by said speed-responsive elements for shifting said member lengthwise of said shaft to turn said lever about its fulcrum; a spring acting on said member to prevent its bein shifted by said speed responsive elements until a predetermined speed of rotation of said shaft has been attained; and means actuated by the turning movement of said lever for exerting additional downward pressure on said presser mechanism in amounts proportional to the speed of rotation of said shaft.

15. In a sewing machine, in combination, a frame including a bracket-arm; an abutment supported by said bracket-arm; a variable speed rotary shaft journaled in said frame; a presser mechanism mounted for vertical movement relative to said frame; means exerting a substantially constant downward pressure on said presser mechanism; a spring arm extending lengthwise of said bracket-arm and bearing intermediate its ends on said abutment, said spring-arm having one end thereof connected with said presser mechanism; a speed-responsive device carried by said shaft; and means actuated by said speedresponsive device and connected with the other end of said spring arm to cause the forward.v end asrnarinons CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 681,684 Diehl et al Sept. 3, 1901 1,202,224. Ringe Oct. 24, 1916 2,174,290

Max Sept. 26, 1939 Certificate of Correction Patent No. 2,541,888 February 13, 1951 BERTHOLD P. PINKVOSS It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows:

Column 6, line 7 2, after the Word auxiliary insert spring;

and that the said Letters Patent should be read as corrected above, so that the same may conform to the record of the case in the Patent Oifice.

Signed and sealed this 24th day of April, A. D. 1951.

THOMAS F. MURPHY,

Assistant Gonnm'm'omr of Patents.