US2280193A

US2280193A - Quick action presser foot

Info

Publication number: US2280193A
Application number: US285696A
Authority: US
Inventors: Vesconte Harold J Le
Original assignee: Union Special Machine Co
Current assignee: Union Special Machine Co
Priority date: 1939-07-21
Filing date: 1939-07-21
Publication date: 1942-04-21
Anticipated expiration: 1959-04-21

Description

April 19 42. H. J. LE VESCQNTE v 2, QUICK ACTION PRESSER' FOOT FiledJul y 21; 19:59 2 Sheets-Sheet 1 1.... lull llrlllgm WITNESSES."

' 9 0/ 71 "m t Uwlat (I v W0 a 455021, e

' gm, BY WW v ATTORNEYS.

April 1942- H. J. LE VESCONTE QUICK ACTION PRESSER FOOT Filed July 21, 1939 2 Sheets-Sheet 2 Q Q Q wma W M YviK I W 1 m a .0 M I "m mm K v INVENTOR: ifarold Jliewsconiz, BY W W WITNESSES:

A TTORNEYS.

Patented Apr. 21, 1942 "ff; T QS T PAT N v i 5 This invention relates to sewing machines, and t is especially concerned with means for holding 1 and feeding-the work,such asthe device commonly known as a presser footi? In 'sewing machines operating at high speeds (suchlas 4000 to 7000 or more stitches .per min ute),fdifiiculty is often experienced in feeding ;the fabric properly andjwithout injury. .The

higherthe speed *ofthe sewing, the greater the pressure that is required at the presser foot to u make the machine feed properly: with lower pressures at the presserffoot, the machine may; even fail to feedthe fabric at all at high speeds. Lightweight fabrics are often marked or rstretched by jthe pressure andifriction of the presser footwwhile for heavy fabrics, the pressure has to be so great that the expenditure of power to operate the machine becomes excessive,

the wear on the presser foot and the associated mechanism is very severe and other drawbacks are encountered. These difiiculties, I have found; are due to inability of the usual springs to return the presser foot and the associated parts as rapidly as the feed dog descends, so that it loses effective feeding engagement with i the work. Upward momentum of the presser bar and foot atthe topof the feed dog rise may also tend to reduce the: feeding pressure between the dog and theworkuobjectionably.

t Efforts have been made to obviate difficulties.

in feeding work at high sewing speeds by modi fying the usual presser bar arrangement so that While the presser barweight rests on the presser foot, the effective spring pressure on the presser foot is exerted independently ofythe presser bar.

not, however, proved Such arrangements have practically successful at high speeds. I i l i I have devised a simple and effective presser foot mechanism which overcomes these drawbacks, and in which thepresser foot is carried a by supporting means which may conveniently be constructed and arranged very much like the usual presser bar, but which does not normally move up and downwtih the presser foot in sewing, like the ordinary presser bar but rather remains stationary. Thepresser foot is held I l the drawings. All the features and combinations fsofar as novel over the prior art.-

; shown or described are, indeed, of my p v invention,

In the drawings, l

- Fig. I isfan end view of a(locksti tch) sewing machineembodying the invention, from in front of the line of stitchformation and work travel.-

Figs, II and III are fragmentary views of the presser footxand associated parts. from the right and left of Fig. I, the needle and needle bar be ingbroken away. 1 i

,Fig. IV shows asectiontaken as indicated, by

thelline and arrows Ill -IV in Fig.1. L

" Fig, V is a fragmentary plan view of parts of the presserlfoot mechanismpthepresser foot itself being omitted. i

Fiavr is a View similar to Fig. I illustrati ng a "modification of the 'presser foot mechanism showninFig. Iyandfl v i v v a Figs. VII, VIII, and IX are fragmentary views similar to Figs. .II, III, and V.

Fig. Iis a view of a sewing machine from in "front of the line of stitch formation and work travel, the work support 26 anctthe stitch plate l 2i appearing edgewisel The horizontalwarm of the machine frame 22 1s concealed by the sewing head 23,; which is shown withits cover plate reinovedluto reveal: the parts within The upright needlebar 24,vvith itsneed1e25, is mounted for up and down movementein suitable hearings in the head 23, and may beactuated by any suituable means,, which need not be described. Be-

neath the st1tchplatec2l is shown a feed dog or member-26 whichfmay be given up and down movements andto and fro movements by any suitable means, not shown, suchas a four-motion .feed mechanism- Adjacent the needle bar 24 is shown an upright supporting rod orbar 29 equipped with a presser foot 3!],with which the feed member 26 coacts throughthe stitch plate 2|. As here shown, the bar 29 is urged downward and heldbdownduringsewing, by a helical J compression spring 3! acting-between a part3! suitably secured to the bar (as by a set screw) against the work by resilient means acting through-a leverage interposed between the foot and said means. Even with alight spring for this purpose, the action of the presser foot is very rapid, and the machine 'feeds thework prop erly and without damage at very high speeds.

and a bearingjand abutment sleeve 33 screwj threaded through the top of the sewing'head 23,

and adjustable up and down therein to control and vary the initial tension of the spring 3l.

On occasion, thejb ar 29may heraised for insertion or removal of the workibefore orafter the sewing of a seam) by any suitable means-as by V a foot-treadleeoperated lever 34 fulcrumed on Various features and advantages of the invention will appear, from the following description of speciesor formsof embodiment; and from the horizontal machine frame arm at 35 and iconnected by a link 36 to a part32 suitably segcured to the bar, as by a set screw, or by a hand lever and cam device 31 fulcrumed on the head 23 at 38, and engaging a part 39 suitably secured to the bar 29. Fig. I also shows thread guides 4|, 42, 43, a frictional thread tension device 44, and a suitably actuated take-up lever 45.

The parts thus farmentioned may be of any usual or suitable type and. construction, and hence need not be further described.

The presser foot 30 is not fixed to the support ing bar 29, but is mounted thereon so as to be movable up and down relative thereto, and is held down on the work, during sewing, by re-' silient means carried by and reacting against the bar, such as a spring 46. As here shown, the presser foot 30 has vertical rectilinear motion relative to the bar 29. The presser foot shank 48 may be attached by a screw to a guide block 49 that slides up and down on a headed guide pin 59 attached to a transverse bracket 5| which projects (to the left) from the bar 29. A multiplying leverage is interposed between the presser foot 30 and'the

spring

46,50 that the up and down motion or deflection of the spring corresponding to the normal up and down movement of the presser foot in sewing is very slightin fact, only a minor fraction of that of the presser foot; The spring 46 is here shown as a cantilever leaf spring attached atone end and bearing at J its other end on a multiplying lever 52 near its fulcrum pivot 53 in the forked outer end of the I v bracket SL, The tension of the spring 46 may be adjusted by any suitable means, such as a screw As shown,

securedon the reduced lower end of the bar 29 by means of one or more set-screws. The block 49 may be prevented from 'turningon the guide pin 59 by a lug 56 on the block engaged in a vertical slot in. a guide plate 51 screwed fast to the bracket 5 I, all as illustrated in Fig. VIII-which is further referred to. hereinafter. The up-bent right-hand end of the spring 46 is attached or anchored by a screw 58 to the corresponding (right-hand) end of the bracket 5|, and its other orfree endbears downward on the lever 52 intermediate its fulcrum pivot 53 on the forked outer end of the bracket 5| and the other or free end of the lever, which in turn bears downward on the block. Thus the lever 52 operates as a lever of the third class. I As shown) the distance from the fulcrum 53 of the lever 52 to the point of engagement of the spring 46 therewith is only about A; to the length of the lever, so that the as the head of the guide pin 50.

In practice, the springs 3| and 46 are so designed and their tensionsare so adjusted (by means of the sleeve'33 and the screw 54) that there is considerable downward pressure on the supporting bar 29 holding its stop collar 60 against the head 23 at 62 when the'presser foot 38 engages the stitch plate 2| with the spring 46 only slightly stressed. In general, spring 46 is made considerably lighter or of smaller scale than the spring 3|. During sewing, the spring 46 normally yields to permit upward displacement of the presser foot 39, relative to the bar 29,'by the' coacting feed member 26; but ordinarily there is no movement or upward displacement of the supporting bar 29since the greatest stress of the spring 46 during the upward movement of the feed dog leaves the force of this spring 46 still too weak to overcome the initial tension of the spring 3| and lift the stop collar 69 of the bar 29 off its coacting stop surface at 62. v In other words, the bar 29 is normally held stationary or fixed against movement relative to the work support 2 8 during sewing-and it might even be fastened in a fixed position, were it not for the desirability of lifting it to lift the presser foot 38 for insertion and removal of work from time to time. Under some circumstances, also, the spring 3| may serve a useful purpose by yielding in case some extraordinary local thickness of the work should require extraordinary upward displacement of the presser foot. When the bar 29 is lifted, the presser foot 30 is also lifted well clear of the work, as a result of the engagement of thehead of pin 59 with the-guide block 49 soon after the bar 29 begins its upward movement from the position shown in Fig. I.

In reality, then, the part 29 is not a presser bar in the usual meaning of this term, but a means of supporting the movably mounted presser foot '39 and the associated parts, and of guiding and confining the foot to a fixed path of movement, and is also made to serve as a means of lifting the presser foot, when desired, by means of the connection provided by the guide block 49 and the head of the'pin 58. The only movable parts are the presser foot 39 with its shank 48 and block 49, and the lever 52, which are in the aggregate quite light, while the deflection of the spring 46 in operation is very slight. Accordingly, this presser foot mechanism is capable of very rapid operation.

The arrangement and construction shown in Figs. VIIX is in the main similar to that shown in Figs. I--V, but has the bracket 5|a, the spring 46, and the lever 52 arranged at right angles to the line of stitching and work feed, and thus extending to the rear in Fig. VI. This allows freer access to the work behind the presser foot 39a. Figs. VI--IX also illustrate minor variations of construction: e. g., the shank 48 is attached to the block 49 by a screw-threaded stud and nut, instead of by a screw as in Figs. I-V. However, theoperation of this mechanism is substantially the same as that of the mechanism illustrated in Figs. I--V.

Having thus described my invention, I claim:

1. The combination in a sewing machine having a work support, a presser-foot support normally held against movement from and toward said work support during sewing, and a presser foot slidably guided by said presser-foot support toward and from said work support, during sewing, of spring means carried by said presser-foot support and reacting thereagainst, and a lever of the third class operatively interposed between said spring means and said presser foot and transmitting the pressure of the spring means to the presser-foot to urge the latter toward said work support.

2. The combination in a sewing machine having a work support, a presser-foot support normally held against movement from and toward said work support, during sewing and carrying presser-foot guide means, and a presser-foot slidably guided by said guide means for movement relative to said presser-foot support toward and from said work support, during sewing, of spring means carried by said presser-foot guide means and reacting thereagainst, and a lever fulcrumed on said presser-foot support operatively interposed between said spring means and said presser-foot, and transmitting the pressure of the spring means to the presser foot to urge the latter toward said Work support;

3. The combination in a sewing machine having a Work-support, a presser-foot support normally held against movement from and toward said Work support, during sewing, and provided with rectilinear guide means, and a presser foot mounted on and movable along said guide means, during sewing, toward and from said work support, of alever fulcrumed on said presser-foot support at one end anda-cting on said presser foot at its other end, and spring means carried by said presser-foot support acting on said lever between its fulcrLuned end and its other end,'

where it acts on said presser foot, and urging the latter toward said work support.

4. The combination in asewing machine having a work support, a presser-foot support normally held against movement from and toward said work support, during sewing, and provided with rectilinear guide means, and a presser foot mounted on and movable along said guide means,

during sewing, toward and from said work support, of a lever fulcrumed on said presser-foot 3 support at one end and acting on said presser foot at its other end, and a cantilever spring extending lengthwise of the lever and transversely of said guide means attached to said presserfoot support at one end and at its other end acting on said lever between its fulcrum and its operative connection to said presser foot, and urging the latter toward said work support.

5. The combination as set forth in claim 4 wherein the presser-foot support comprises a bracket transverse to said guide means, and the lever and cantilever spring are mounted on opposite ends of said bracket, respectively.

6. The combination as set forth in claim 4 wherein the presser-foot support comprises a bracket transverse to said guide means, and the lever and cantilever spring are mounted on opposite ends of said bracket,,respectively with an adjusting screw threaded in said bracket at an intermediate point in the length of the bracket bearing on said spring at an intermediate point in the length of the spring betweenits attachment to the bracket and its end bearing on the lever.

7. Thecombination as set forth in claim 4 wherein the presser-foot support comprises a supporting rod extending in the general direction of the presser-foot movement toward and from the work support, and a bracket projecting to one side from said rod, and the lever is fulcrumed on the end of the bracket remote from said rod, while the spring is attached to the bracket adjacent said rod.

HAROLD J. LEV VESCONTE.