US3044428A

US3044428A - Low mass presser mechanism for sewing machines

Info

Publication number: US3044428A
Application number: US862209A
Authority: US
Inventors: Arthur N Hale; John N Covert; Robert W Volkmann
Original assignee: Union Special Machine Co
Current assignee: Union Special Machine Co
Priority date: 1959-12-28
Filing date: 1959-12-28
Publication date: 1962-07-17
Anticipated expiration: 1979-07-17

Description

July 17, 1962 A. N. HALE ETAL 3,044,428

LOW MASS PRESSER MECHANISM FOR SEWING MACHINES Filed Dec. 28, 1959 2 Sheets-Sheet 1 FIG. I.

a z i O /l7 .8 mi N 11 I 20 l 24 q, ,8 l 9' 8 l0 |o I I] IO 5 I I I 112: I! I l-- 28 I5 "IQ I E] FIG 2 0 Pl m. 'l

A. N. HALE J. N. COVERT R. W. VOLKMANN INVENTORS BY wmw ATTORNEYS July 17, 1962 A. N. HALE ETAL LOW MASS PRESSER MECHANISM FOR SEWING MACHINES 2 Sheets-Sheet 2 Filed Dec.

FIG. 5.

A. N. HALE J. N. COVERT R. W. VOLKMANN INVENTORS ATTORNEYS United States Patent Ofi ice dfiddfizd Patented July 17, 1962 The specification which follows relates to improvements in a presser foot for high speed sewing machines. It meets the prOblems presented by increase in the speed of sewing machines and difficulties arising from new synthetic fabrics.

In the trend toward obtaining ever greater speeds in Sewing machines, it has been considered necessary to apply increasing pressure to the presser foot in order to feed the work properly. However, in machines of high speeds, where insufliciently pressure is supplied to the presser foot, it has a tendency to break contact with the feed dog on impact and again at the point where the dog begins its downward motion, in other words, the inertia of the presser foot is too great to allow it to follow the feed dog at high speed.

One result of this failure of the presser foot'to follow closely the work feeding motion of the feed dog is that less feed contact results between the feed dog and the foot and thereby the length of the stitch is reduced. This condition is caused by the inertia of the aggregate mass of the presser foot, presser bar, strike-off wire, the strikeoff wire holder and other related parts moved by the feed dog. The greater the mass, the greater must be the pressure applied to the parts in order to overcome their inertia. The inertia is directly proportional to the mass of the parts which have to be moved.

In order to have the presser foot more closely follow the vertical movements of the feed dog at high speeds a material increase in pressure on the presser bar is neces sary. However, such increase in pressure has caused several adverse side effects; such as, producing puckered seams, uneven ply feeding, and the breaking of the thread chain between garments.

Improvement was made by redesigning the presser bar parts of lighter weight. However, with the advent of presentday fabrics of the Wash and wear type, there is still a well defined tendency to pucker even with the use of less pressure afforded by the use of presser bar parts of light weight. To overcome this difliculty, the present invention has been developed in the direction of mini mixing the mass of the moving parts at high speed and effecting close response to the movements of the feed dog.

One of the main objects of the invention is to provide a presser foot, the presser bottom of which will closely follow the movements of the feed dog but will not transfer such feed dog movement to the presser bar and its related parts, as is ordinarily the case in the usual sewing machine.

Another object of the invention is to restrict the movement to the presser foot bottom only against a spring mounted on the presser foot.

A further object of the invention is to utilize a spring having unrestrained movement which will not cause wear on the pivot arm or link.

Among the objects of the invention is to apply spring pressure to the presser foot bottom in a direction approximately perpendicular to the plane through which the fabric is being fed.

A still further object of the invention is to provide an extremely fine adjustment under the spring.

Incidental to the novel adjustment of the spring is a self-locking fixture.

It will also be noted that by the design of a foot bottom mounting, it is prevented from any side play.

The purposes of this invention have been carried out by providing a presser foot carrying a forked bracket with a hinged link from which the foot bottom is pivoted and applying spring power to the line vertically, so that there need to be movement only by the foot bottom and the link thus capable of following the movements of the feed dog with great rapidity.

The preferred form of this invention has been illustrated by way of example on the accompanying drawings in which:

FIGURE 1 is a side elevation of a sewing machine on which the novel presser foot has been mounted;

FIGURE 2 is a front elevation of the improved presser foot;

FIGURE 3 is a perspective view of the slide and operating spring;

FIGURE 4 is an enlarged side elevation;

FIGURE 5 is a rear elevation of a modified form and FIGURE 6 is a perspective view of the separated parts of the link, slide and foot bottom of the modified form. r

On the drawings there is shown a presser bar 7 which forms a mounting for the presser foot 8 in the usual manner. The presser bar is adjusted in such a manner that it will apply no, or at least very little pressure to the presser foot. The presser foot 8 has a laterally extending bracket 9. This is in the form of a bifurcated fork having spaced parallel side plates it), 10. s

These side plates have two pairs of aligned holes 11. A link 12 is carried by' a pivot pin 13 in one pair of the holes. 1 Y

A stop pin 14 is mounted in one pair of holes provided above each of the pairs of holes 11.

A foot bottom 15 is pivoted to the forward end of the link 12 between flanges 16 which fit loosely outside of the link 12. This insures that the foot bottom will be restricted to vertical oscillation free from lateral displacement.

A diagonal arm 17 is mounted upon the bracket 9. This arm carries a screw-threaded stud l8 firmly attached by means of a locknut 19. The stud 18 is provided with a knurled nut 2d which may be 'adjustably threaded on the stud.

Resilient means for holding the link 12 and the foot bottom 15 down is provided by a wire spring 21. This spring has an upper loop 22 which, as shown in FIGURE 1, passes around the stud 18 and the sleeve of the'adjusting nut 20. i

At an intermediate point the spring 21 is provided with a pair of opposite loops 23. These loops are held by a hinge screw 24 passing between the

side plates

10,10 of the bracket.

A shoe plate, 25 rests upon the upper surface of the link link 12 and shoe 25 are smooth so that sliding movement will be possible when lubricated and in a condition of minimum friction.

The top surface of the shoe 2 5 has a' transverse groove 26. e s

The lower ends of the spring 21 are turnedinwardly at right angles as shown at 27 and fitted within the transverse groove 26.

Adjusted tension of the spring 21 is exerted upon the shoe plate 25 in a direction approximately perpendicular to the plane in which the fabric is fed by the feed dog 28. In the present instance this is exerted vertically. The feed dog lifts the shoe bottom 15 in high speed movements.

a sence If thepresser foot is lifted, such aswhen it is necessary to lift the presser foot for insertion of the fabric, the link 12 comes in contact with the stop pin 14 and thus prevents the bottom 15 from dropping beyond thedesired point.

There is an appropriate freedom of movement between the shoe plate 25 and the top surface of the link 12. This is practically without friction. Should a rather heavy seam present itself to the presser foot it will cause the shoe plate to move forward on the link a greater amount than that normally due to the usual feed motion because of the greater lifting movement to the presser foot as it goes over the seam. Y j V In the modification shown in FIGURES and 6, the novel tension upon the link 29 is transmitted to a cornpensating presser foot of the type disclosed in United States Letters Patent 2,288,051."

In this instance the link has parallel depending

flanges

30, 31. A bottom member 32 is provided with an,

upstanding block 33. This block is held inside the flange 30 by means of a transverse pin 34. Thus the block 33' fits closely against the inner side of the flange 3d and slightly spaced'from the lower surface of the link 29, so that the member 32 can move relative to the link 29 only in a pivotal movement.

A second bottom member 35 is fitted against the inner side of the flange 31. The member 35 .has two spaced

lugs

36, 36. The

lugs

36, 36 overhang the side of the 7 member 32, which thus prevents the member 35 from dropping out of position.

The

lugs

36, 36 have recesses in the top each containing a coil spring 37 which is under tension against the bot-. tom surface of the link 29. Thus the bottom member 35 may move vertically with respect to the member 32.

The pressure of the feed dog 23 against the undersides of

members

32, 35, is thus transmitted to the link 29. The pressure is there exerted against the shoe plate 25 as above described.

In theabove mounting of the foot bottom it will be observed that in normal operation at high speed, the movement caused by the action of the feed dog will be transmitted through the

link

12 or 29 as the case may be,

against the tensioned shoe plate 25. Here the vertical movement is absorbed by the resilience of spring 21 without transmitting force againstthe presser bar 7. There is thus no possibility of a binding condition between sliding members. Also, the mass which must be moved by the feed dog is limited to that of the presser foot-bob a self-locking feature. I The essential features of the invention having been de scribed and illustrated in the preferred form by way of example, permit variation in minor details of material and proportions without departing from the scope of the invention as defined in the following claims.

What we claim is: a 1. A presser mechanism for sewing machines comprising a presser bar, a presser foot attached thereto, a forked bracket on the presser foot, a'link pivoted to the bracket, a foot bottom pivoted to the outer end of the link, and resilient means hinged on the presser foot and having a free end pressing downwardly on the link 'in front of its pivot with the bracket.

2. A presser mechanism for sewing machines comprising a presser bar, apress'er foot attached thereto, a

forked bracket on the presser foot, a link, a pin for the link selectively pivoted on the bracket, a stop pin selectively carried by the bracket in the path of the link, a foot bottom pivoted to the outer end of the link, and resilient means hinged on'the presser foot and having a free end pressing downwardly on the link in front of its pivot with the bracket.

3. A presser mechanism for sewing machines comprising a presser bar, a presser foot attached thereto, a forked bracket on the presser foot, a link pivoted to the bracket, a foot bottom pivoted to the outer end of the link, a shoe plate slidably resting on the link and resilient means hinged on the bracket and having a free end presslog downwardly on the shoe plate.

A 4. A presser mechanism for sewing machines comprising a presser bar, a presser foot attached thereto, a forked bracket on the presser foot, a link-pivoted to the bracket, a toot bottom pivoted to the outer end of the link, a shoe plate slidable .on the link, a spring pivotally mounted in said bracket with one end resting on said shoe plate and adjustable means on the bracket for applying tension to the opposite end of' the spring.

"5. A presser mechanism for sewing machines com prising a presser bar, a presser foot attached thereto, a

' forked bracket on the presser foot, a link pivoted to the bracket, a foot bottom pivoted to the outer end of the link, a shoe plate slidable on the link and an arm on the on the bracket, a rearwardly extending screw mounted on the arm, a nut adjustably carried on the screw, a spring loop pivotally mounted in said bracket with one end resting on said shoe plate-and the opposite end extending upwardly with its looped end around the screw in frontof the nut.

7. A presser mechanism for sewing machines comprising a presserbar, a presser foot attached thereto, a forked bracket on the presser foot, a link pivoted to the bracket, parallel depending flanges on the link, a foot bottom pivoted to the outer end of the link, an upstanding block on the bottom between said flanges and resilient means hinged on the presser foot and having a free end pressing downwardly on said link in front of its pivot with the bracket.

8. A presser mechanism for sewing machines comprising a presser bar, a presser foot attached thereto, a

forked bracket on the presser foot, a link pivotally attached at one end to said bracket, a presser foot bottom attached tothe other end of said link, resilient means hinged intermediate its ends to said presser foot with its front end bearing down on the said link and means carried by said bracket to apply tension to the opposite end of said resilient means.

References Cited the file of this patent UNITED STATES PATENTS 963,135 Gatchell July 5, 1910 1,339,121 Moffatt May 4, 1920 1,921,277 Wolf Aug. 8, 1933 1,943,203 Chudner Jan. 9, 1934 2,419,494 Knau's Apr. 22, 1947 2,730,979 Bell Jan. 17, 1956