US3511198A - Presser foot for sewing machines - Google Patents

Description

May 12, 1970 s. HACKlNG PRESSER FOOT FOR SEWING MACHINES Filed July 24, 1968 FIG. I

INVENTOR SAMUEL HACKING BY gamma, 7"

ATTORNEYS:

United States Patent 3,511,198 PRESSER FOOT FOR SEWING MACHINES Samuel Hacking, 330 Hyde St., Fall River, Mass. 02720 Filed July 24, 1968, Ser. No. 747,357 Int. Cl. Db 29/00 US. Cl. 112235 8 Claims ABSTRACT OF THE DISCLOSURE A sewing machine pressure foot assembly having tension springs exerting a force between the shoe and shank tending to rotate the shoe about a horizontal pivot axis joining the shoe and the shank. Adjusting means are provided for manually adjusting the force exerted by the tension springs.

This invention relates to sewing machine presser feet, and more particularly to an improved presser foot assembly having tension spring means exerting a force between the shoe and shank of the foot to resiliently control the position of the shoe about its horizontal mounting pin.

Presser feet employed in sewing machines conventionally include a vertically extending shank for attaching the foot assembly to the sewing machine, and a shoe pivotally mounted on the lower end of the shank for limited pivotal rotation about a horizontal axis extending substantially transverse to and above the path of travel of material through the sewing machine. The pivotal mounting of the shoe permits the shoe to glide smoothly over uneven thicknesses of material passing through the machine while exerting a vertical downward force on the material to hold the material into firm engagement with the serrated teeth of the machine feed dogs. Such devices are frequently equipped with a thread cutting knife mounted on the shoe, with a resilient spring thread holder adjacent the knife so that, when an article is sewn, the machine operator can draw the thread through the spring thread holder and across the knife to cut the thread. The thread holder releasably retains the end of the thread remaining in the machine so that the machine does not become unthreaded as the next article is passed into the sewing mechanism.

When the sewing machine is running without work in the machine, the bottom surface of the presser foot rests directly upon the needle plate and feed dogs of the sewing machine, with the machine thread extending between the shoe and the feed dogs. Feeding motion of the dogs rapidly raises the presser foot at the beginning of the feeding motion, and permits the foot to be lowered at the end of the feeding motion. A resilient spring carried by the machine urges the presser foot assembly downward to maintain the presser foot in contact with the feed dogs and/ or needle plate of the machine.

It has been considered desirable in many cases to resiliently bias the heel of the presser foot shoe downwardly to thereby elevate the toe of the shoe to readily accommodate the feeding of work material into the machine and to prevent the shoe from pivoting freely when the foot is raised above the needle plate. This is normally accomplished by a coil spring positioned betwen the shank and the heel to urge the heel downward. It has also been known to employ a plurality of these coil compression springs between the shank and shoe to resiliently urge the shoe to the desired position.

It has been found that the repeated impact between the presser foot shoe and the machine feed dogs frequently cuts or breaks the thread retained by the resilient spring thread holder on the presser foot. This is particularly true where the thread extends beneath the heel of the shoe and where the shoe is urged downward at the heel by a spring 3,511,198 Patented May 12, 1970 positioned between the shoe and shank. Applicant has found, however, that this tendency to cut the thread can be greatly reduced by resiliently urging the heel of the shoe upward and the toe downward so that more of the reaction force between the feed dogs and shoe is carried by the toe of the shoe. Accordingly, it is an object of the present invention to provide an improved presser foot assembly including means for applying a force between the shoe and shank creating a moment tending to rotate the shoe to lift the heel and depress the toe.

Another object is to provide such a presser foot assembly employing tension spring means for applying the force between the shoe and shank.

Another object is to provide such a presser foot assembly employing a pair of tension springs, one applying a lifting force to the heel and the other a lifting force to the toe of the shoe.

Another object is to provide such a presser foot assembly including two tension springs applying a force to the shoe, with means for adjusting the force applied by each spring.

In the attainment of the foregoing and other objects, an important feature of the invention resides in providing a presser foot assembly including bracket means on the shank and on the shoe of the assembly for supporting tension spring means applying a force creating a moment tending to rotate the shoe about its pivotal mounting. Preferably, two tension springs are employed, one applying a force having a vertical component rearwardly of the shoes pivot axis and the other applying a force having a vertical component forward of the pivot axis. Means are provided for adjusting the magnitude of force applied by each spring so that the equilibrium position of the shoe with respect to the shank may be adjusted as desired or necessary.

Other objects and advantages of the invention will become apparent from the following detailed description, taken with the drawings, and which:

FIG. 1 is a perspective view of a presser foot assembly according to the present invention;

FIG. 2 is a side elevation view of the apparatus shown in FIG. 1;

FIG. 3 is an elevation view similar to FIG. 2 and illustrating the side of the apparatus opposite the side shown in FIG. 2;

FIG. 4 is a front elevation view of the presser foot assembly;

FIG. 5 is a rear elevation view of the assembly; and

FIG. 6 is a sectional view taken on line 6-6 of FIG. 2.

Referring now to the drawings in detail, the presser foot assembly according to the present invention is referred to generally by the reference numeral 10 and includes a conventional vertically extending shank 11 having a channel-shaped groove 12 formed in one side surface thereof, with a U-shaped notch 13 for rigidly mounting the assembly on a sewing machine. Shank '11 is provided at its lower end with a forwardly extending mounting bracket portion 14 received within a yoke defined by a pair of upwardly extending flanges 15, 16 on a presser shoe assembly 17. The presser shoe 17 is pivotally supported on bracket 14 by a horizontal pin 18 extending transverse to the direction of feed of material through the machine. For convenience, the portion of the shoe rearwardly of the mounting pin 18 will he referred to as the heel while the forwardly extending, upwardly curved portion of the shoe will be referred to as the toe portion. Pin 18 may be in the form of a headed screw which retains a thread cutting knife 19 mounted on the side face of flange 16. A resilient thread-holding spring 20 is mounted on the bottom surface of and extends rearwardly from shoe 17.

A bracket 21 is integrally formed on and extends rearwardly from the heel of the shoe, with bracket 21 having a lower surface which is generally spoon-shaped and curved upwardly and rearwardly to act as a thread guide. An opening 22 formed in the upper portion of bracket 21 acts as an anchor for one end of a coil tension spring 23. The other end of spring 23 is attached to an eyelet in the end of a threaded rod 24 extending through a rearwardly extending bracket 25 on shank 11. A nut 26 is threaded onto the end of rod 24 to adjust the position of the rod 24 within bracket 25 to thereby vary the tension on spring 23. If desired, a set screw 27 may be mounted in bracket 25 to lock rod 24 against movement in the event of nut 26 becoming loose during operation of the machine.

A second bracket 30 is formed on and extends laterally outward from shank 11, with bracket 30 supporting a threaded rod member 31 extending therethrough with a nut 32 threaded onto the end of rod 31 to adjust the position of the threaded rod within the bracket. A set screw 33 is provided to positively lock the threaded rod against movement in the event of loosening of nut 32. A second tension spring 34 has one end attached to an eyelet in rod 31 and its other end attached to a bracket 35 mounted on and projecting upwardly from the toe portion of the presser foot shoe by a pair of screws 36.

The presser foot assembly 10 is illustrated in the drawings with the bottom of the shoe in the horizontal position which it normally assumes during operation of the sewing machine when the presser foot is resiliently retained in contact with the sewing machine needle plate and feed dogs. As illustrated in FIG. 3, the needle plate has a horizontal upper surface with elongated openings formed therein through which the serrated feeding surface of the machines feed dogs 42 project. Work material is fed through the machine in the direction of arrow 44 over the top surface of needle plate 40 and beneath the toe of shoe 17 until the material is engaged by the feed dog 42. The work material is fed through the machine by the conventional four-motion action of the feed dogs until the trailing edge of the work material eventually passes beneath the shoe rearwardly of the heel. The operator then manually draws a short length of thread over the top of the rearwardly projecting portion of thread holding spring 21, and forward to engage the thread with the cutting edge of knife 19. In this movement, the thread is guided by the curved surface of the bracket 21, and the cut ends of the thread remaining in the machine are resiliently retained between the spring 20 and the lower surface of shoe 17. Thus, it should be apparent that any further operation of the sewing machine before another Work piece is presented beneath the presser foot assembly will result in the thread in the machine being repeatedly caught beneath the surface of the shoe and the serrated teeth on the feed dogs. However, by adjusting the tension on the springs 23 and 34 to apply a moment to the shoe 17 tending to raise the heel and lower the toe, the force between the presser foot and the feed dogs may 'be more equally distributed to thereby reduce the tendency to cut the thread and result in a more even wear of the serrated teeth on the feed dogs. By adjusting the tension on the springs, the presser foot may readily be adjusted to its optimum working position for any type or weight material or thread.

While I have disclosed a preferred embodiment of my invention, I wish it understood that I do not intend to be restricted solely thereto, but that I do intend to include all embodiments thereof which would be apparent to one skilled in the art and which comes within the spirit and scope of my invention.

What is claimed is:

1. In a presser foot assembly for use on a sewing machine, said presser foot assembly including a shank for mounting the assembly on the machine, a shoe member, and means supporting said shoe member on said shank for limited pivotal movement about a horizontal axis extending generally transverse to the path of travel of work through the machine, the improvement comprising tension spring means including an elongated tension spring member having one end connected to said shoe and its other end connected to said shank and exerting a force therebetween tending to rotate said shoe about said horizontal axis.

2. A presser foot according to claim 1 wherein said shoe member comprises a toe portion extending forwardly of said axis and a heel extending rearwardly of said axis said tension spring member being connected to said shank and to said heel and applying a moment about said horizontal axis in a direction tending to lift said heel and depress said toe portion.

3. In a presser foot assembly for use on a sewing machine, said presser foot assembly including a shank for mounting the assembly on the machine, a shoe member, and means supporting said shoe member on said shank for limited pivotal movement about a horizontal axis extending generally transverse to the path of travel of work through the machine, the improvement comprising tension spring means including a first spring connected to said shank and to said heel rearwardly of said horizontal axis and applying a moment about said horizontal axis in a direction tending to rotate said shoe about said horizontal axis in a direction to lift said heel and depress said toe portion, and tension adjusting means for varying the force exerted by said first spring between said heel and said shank.

4. In a presser foot assembly for use on a sewing machine, said presser foot assembly including a shank for mounting the assembly on the machine, a shoe member, and means supporting said shoe member on said shank for limited pivotal movement about a horizontal axis extending generally transverse to the path of travel of work through the machine, tension spring means including a first spring connected to said shank and to said heel rearwardly of said horizontal axis and applying a moment about said horizontal axis in a direction tending to rotate said shoe about said horizontal axis in a direction to lift said heel and depress said toe portion, and a second spring connected to said shank and to said toe portion forward of said horizontal axis, said second spring applying a moment about said horizontal axis in opposition to the moment applied by said first spring and tending to lift said toe portion and depress said heel, the magnitude of the moments applied by said first and second spring means normally being balanced when said toe portion assumes a position below said heel.

5. The presser foot according to claim 4 further comprising first and second tension adjusting means, said first tension adjusting means being manually adjustable to vary the force exerted by said first spring and said second tension adjusting means being manually adjustable to adjust the force exerted by said second spring.

6. A presser foot assembly for a sewing machine comprising a shank for mounting the assembly on a sewing machine, a shoe, means supporting said shoe on said shank for limited pivotal movement about a horizontal axis extending generally transverse to the path of work through the machine, said shoe including a forwardly extending toe portion and a heel portion, a thread guide on said heel, said thread guide having a curved lower surface extending upwardly and rearwardly from the bottom and one side surface of said heel to act as a guide for guding thread into a cutter carried on said foot, a bracket on said shank and extending laterally therefrom, and a tension spring member extending between said bracket and said thread guide exerting an upward force on said heel portion to produce a moment tending to rotate said shoe about said horizontal axis in a direction to lift said heel portion and depress said toe portion.

7. The presser foot assembly defined in claim 6 further comprises a second bracket on said shank and projecting laterally from one side thereof above said shoe, third bracket means mounted on a top surface of said toe portion, and second tension spring means extending between said second and third bracket means, said second tension spring means exerting an upward force on said toe portion producing a moment tending to rotate said shoe about said horizontal axis in a direction to lift said toe and depress said heel.

8. The presser foot assembly defined in claim 7 further comprising tension adjusting means carried by said first and second bracket means, respectively, said ten- References Cited UNITED STATES PATENTS 2,494,790 1/1950 Zahler 112-235 2,932,269 4/1960 Kuhar 112-235 3,002,477 10/ 1961 Silberman 112235 PATRICK D. LAWSON, Primary Examiner

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