Presser Mechanism For Sewing Machines

Abstract

This disclosure relates to a low inertia adjustable stroke presser foot for sewing machines which is operable to feed the uppermost ply of superimposed plies being sewn to compensate for the drag exerted by the presser foot sole upon the upper ply. The presser foot is automatically driven through its cooperation with the feed dog and effects the feeding of the upper ply at the termination of the work feeding action of the feed dog. The presser foot includes two sole plates mounted for operation in unison while being relatively movable to one another to compensate for a variation in the number of plies between the two sole plates.

Description

This invention relates in general to new and useful improvements in sewing machines, and more particularly to an improved presser foot assembly for sewing machines of the type in which a presser foot is disposed on one side of the work and is biased in opposition to a movable work feeding member disposed on the opposite side of the work. The invention particularly relates to a presser foot assembly of this type wherein different numbers of work plies underlie different portions of the presser foot and separate sole plates are provided for engaging the different plies.

BACKGROUND OF THE INVENTION

This invention particularly relates to a low inertia adjustable stroke presser foot for sewing machines of the type disclosed in the copending application of Edgar Schoij and Frederick M. Klose entitled PRESSER MECHANISM FOR SEWING MACHINES, Ser. No. 878,635 filed Nov. 21, 1969, now U.S. Pat. No. 3,623,441.

The sole plates of the various presser foot arrangements disclosed in the aforementioned copending application Ser. No. 878,635 is a planar sole plate intended primarily for the sewing of plies which extend entirely beneath the presser foot. However, there are many sewing operations wherein one portion of the presser foot overlies only one ply of work, for example, and a second portion of the presser foot overlies a multiple number of plies of work. This is particularly true in such operations as sewing on pockets, collars, cuffs, etc. The situation also exists in such hemming operations as shirt sleeves, blouses, skirts.

In the past, there have been developed compensating presser feet of the type wherein two sole plates are provided, the sole plates being relatively movable with respect to one another whereby one sole plate may engage only a single work ply and the other sole plate will engage one or more work plies which are being stitched to the one work ply. Typical of these compensating presser foot constructions are those found in the patents to John T. Enos entitled SEWING MACHINE PRESSER-FOOT, U.S. Pat. No. 2,652,016, granted September 15, 1953, and James A. Pisano entitled CORDING PRESSER-FOOT FOR SEWING MACHINES, U.S. Pat. No. 2,807,225, granted Sept. 24, 1957. While the individual sole plates of these prior presser foot constructions are mounted on common pivots carried by a bracket, the constructions in no way co-ordinate the pivoting of the two sole plates nor is such co-ordination necessary in that the bracket is rigidly mounted on the presser bar and there is no change in the angular relation of the bracket with respect to the plane of the work being stitched.

SUMMARY OF THE INVENTION

In accordance with this invention, there is provided a low inertia adjustable stroke presser foot for sewing machines which is also of the compensating type and is provided with first and second sole plates mounted both for movement in unison and for individual movement relative to one another.

A principal feature of the invention is the provision of a support arm which is part of a lever pivotally mounted for cooperating reaction with respect to a four motion feed assembly whereby a sole plate or sole plates carried thereby may automatically feed the upper work layer or layers to compensate for the resistance to movement of the upper work ply with the lower work ply as it is being fed by the feed mechanism. This support arm is provided with first and second sole plates which are mounted on a pivot pin carried by the support arm with the first and second sole plates having cooperating means whereby the first and second sole plates generally move in unison with respect to the support arm and at the same time are relatively movable with respect to one another, primarily in a vertical direction, to compensate for the varying number of plies underlying the two sole plates.

A feature of the invention is the inter-relationship of the two sole plates whereby the two sole plates react against one another for relative movement and at the same time are generally movable together as a unit for pivoting about the pivot pin mounting the same.

With the above and other objects in view that will hereinafter appear, the nature of the invention will be more clearly understood by reference to the following detailed description, the appended claims and the several views illustrated in the accompanying drawings:

IN THE DRAWINGS

FIG. 1 is a partial left end elevational view of a lockstitch machine with parts broken away and shown in section, and incorporating the presser mechanism of this invention.

FIG. 2 is a front elevational view of the presser mechanism of FIG. 1 together with adjacent portions of the machine.

FIG. 3 is an enlarged rear elevational view of the presser mechanism.

FIG. 4 is a vertical sectional view taken along the line 3--3 FIG. 4 and shows the specific details of the presser mechanism.

FIG. 5 is an enlarged fragmentary vertical sectional view taken along the line 5--5 of FIG. 1.

FIG. 6 is a fragmentary vertical sectional view taken along the line 6--6 of FIG. 4 and shows the relationship of work plies with respect to the sole plates.

FIG. 7 is an exploded perspective view showing the double sole plate construction of the presser mechanism.

Referring now to the drawings in detail, it will be seen that there is illustrated in FIG. 1 a base 10 of a lockstitch machine with a conventional feed mechanism, generally identified by the numeral 11, including a feed dog 12. There is also illustrated the customary rotary hook 13 and throat plate 14, all mounted on the base 10.

Above the base 10 there is illustrated a portion of the conventional head 15 which carries in the normal manner a presser bar 16 and a needle bar 17 mounted for vertical reciprocal movement in bushings 18,19, respectively, with a needle 20 being mounted in the lower end of the needle bar 17. A presser foot, formed in accordance with this invention and generally identified by the numeral 21, is carried by the lower end of the presser bar 16 and includes a bracket 22 which, as is best shown in FIG. 4, has a bore 23 receiving a reduced diameter portion 24 of the presser bar 16. The bracket 22 carries suitable set screws 25 (FIG. 2) securing the same on the presser bar 16.

As is best shown in FIGS. 3 and 4, the bracket 22 has a solid top portion 26 and two downwardly spaced wall portions 27. A stud or pivot pin 28 extends through and between the walls 25 with one end portion 30 of the pivot pin 28 being threaded and being threaded into a like threaded bore 31 in one of the wall portions 27. A bellcrank type lever 32 having a centrally located bushing 33 receiving the pivot pin 28 is mounted for pivotal movement relative to the bracket 22 with an upper portion of the lever 32 being disposed between the walls 27.

With particular reference to FIG. 4, it will be seen that the lever 32 includes an upper arm 34 which extends horizontally to the left between the walls 27 and terminates in a bifurcated portion 35. An eyebolt 36 has the eye thereof mounted within the bifurcated portion 35 for pivotal movement by means of a pin 37 carried by the bifurcated portion 35 and extending transversely thereof. The bolt 36 extends upwardly and through an elongated slot 38 in the solid portion 26 of the bracket 22 and threadedly engaged on the upper end portion of the bolt 36 is a nut 40 having a generally conical shoulder portion 41 depending therefrom.

A spring 42 is contained on the bolt 36 between the nut 40 and the solid portion 26 of the bracket 22 by the nut 40. It will be readily apparent that when the nut 40 is properly adjusted, the spring 40 will be compressed and the bolt 36 tensioned so as to urge the lever 32 to pivot about the pivot pin 28 in a clockwise direction. A stop nut 43 is adjustably threaded on the bolt 36 and is engageable with the bracket 22 to limit pivotal movement of the lever 32 in a counterclockwise direction. The stop nut 43 is retained in an adjusted position by means of a lock nut 44.

With particular reference to FIGS. 1 and 5, it will be seen that the bracket 22 has formed in the solid upper portion 26 thereof between the slot 38 and the presser bar 16 a threaded bore 45 opening entirely therethrough and having adjustably positioned therein a stop screw 46 which is engageable with the upper surface of the arm 34 of the lever 32. The stop screw 46 limits the pivotal movement of the lever 32 in a clockwise direction.

The lever 32 also includes a second arm 47, which will be described hereinafter as a support arm. The support arm 47 extends angularly downwardly and to the right from the pivot pin 28 and terminates in a bifurcated portion 48, as is best shown in FIGS. 6 and 7. The bifurcated portion 48 includes a pair of spaced walls 50,51 having mounted therein transversely aligned bearings 52,53, respectively. The bifurcated portion 48 carries a transverse pivot pin 54 which has end portions thereof seated within the bearings 52, 53 for rotation relative to the bifurcated portion 48.

The pivot pin 54 carries two separately formed and separately acting sole plates generally identified by the numerals 55 and 56.

The sole plate 55 includes a lower work engaging plate member 57 which has a mounting block 58 extending upwardly therefrom. The mounting block 58 has a transverse bore 60 therethrough of a size to receive the pivot pin 54. The pivot pin 54, in the final assembly of the sole plates 55,56, with the bifurcated portion 48, is locked in a center position to the mounting block 58 by means of a set screw 61. Thus, the sole plate 55 is mounted for pivotal movement only with respect to the bifurcated portion 48, the pivot pin 54 rotating within the bearings 52,53.

It is also to be noted that the upper portion of the mounting block 58 is contoured to provide suitable clearance for the upper part of the bifurcated portion 48. Furthermore, the block 58 is offset outwardly from the inner edge of the plate member 57 to define a lower ledge 62. In addition, the upper part of the block 58 projects inwardly over and beyond the lower ledge 62 to define an overhanging upper ledge 63. The ledges 62 and 63 cooperate with the sole plate 56 in a manner to be described hereinafter.

The sole plate 56 also includes a lower work engaging plate member 64 which has a mounting block 65 extending upwardly therefrom. The mounting block 65 has formed therein a transverse groove 66 of a width corresponding to the diameter of the pivot pin 54. Thus, the sole plate 56 is mounted for both rocking and vertical sliding movement relative to the bifurcated portion 48.

On opposite sides of the groove 66, the mounting block 65 is provided with a pair of bores 67 (FIG. 4) in which are seated lower ends of springs 68. It is also to be noted that the lower part of the mounting block 65 is generally aligned with the inner edge of the plate member 64 and that the upper part of the block 65 overhangs inwardly beyond the inner edge of the plate member 64 to define an abutment 70.

When it is desired to assemble the plate members 55,56 with the support arm 47, the springs 68 are engaged beneath the ledge 63 and then compressed, after which the sole plates 55,56 are slid together so that the inner surfaces of the blocks 58,65 abut one another. At this time downward movement of the sole plate 56 relative to the sole plate 55 due to the urging of the springs 68 is limited by engagement of the abutment 70 with the lower ledge 62. The sole plates 55,56, so coupled, are then positioned between the walls 50, 51 of the bifurcated portion 48 and the pivot pin 54 is passed through the bearing 52, the bore 60, the groove 66 and the bearing 53. With the pivot pin 54 centered, the set screw 61 is tightened to lock the assembly together.

It will be readily apparent that the sole plates 55, 56 are mounted for pivoting in unison about the pivot pin 54 while at the same time the sole plate 56 is movable relative to the sole plate 55 both vertically and through a limited rocking movement.

Referring to FIG. 4, it will be seen that a spring, generally identified by the numeral 71, is carried by the lever 32 and reacts on the rear portion of the plate member 57 urging the same to pivot in a counterclockwise direction (FIG. 4) about the pivot pin 54 and to retain a normal horizontal position. The spring 71 has an upper end portion 72 which is secured to the underside of the arm 34 by a screw 73 threaded thereinto. The spring 71 also has a generally S-shaped central portion 74 and a lower portion 75 which lower portion 75 engages the plate member 57 and serves to keep the sole plates 55,56 in a selected angular relation relative to the support arm 47, more particularly in a horizontal position when the presser mechanism is lifted for insertion or removal of a workpiece.

Referring now to FIG. 6, it will be seen that there is illustrated a practical application of the presser foot 22 in applying a shirt pocket 76 to a shirt 77. The edge of the shirt pocket has an inwardly directed fold 78. Thus, the sole plate 55 overlies three layers of work while the sole plate 56 overlies only a single layer of work. When the presser bar 16 is moved downwardly to apply the presser foot 22 to the work, the sole plate 55 would apply the desired pressure to the three plies of work with the support arm 47 being disposed at the desired angle through the compression of the spring 42 so as to affect the necessary additional feeding of the material of the pocket 76 relative to the base material of the shirt 77. At the same, time, the sole plate 56 would offset downwardly relative to the sole plate 55 under the influence of the spring 68 and serve as an edge guide for the pocket 76 and also to prevent flagging of the material.

It is to be understood that the amount of pressure applied to the material being stitched by the main sole plate 55 will depend upon the compression of the spring 42 in that this is adjustable by positioning the nut 40. The amount of pressure applied to the material will depend on the type of finish of the material or the thickness of the material. For example, more pressure would be required for smooth or thin material than for rough or thick material in order to obtain a flat, pucker-free seam.

It is once again pointed out here that without consideration being given to the sole plate 56, the sole plate 55 will function in the manner described in the afore-mentioned copending application Ser. No. 878,635 while the sole plate 56 will have no feeding function.

Although only a preferred embodiment of the presser foot mechanism has been specifically illustrated and described herein, it is to be understood that minor variations may be made in the presser foot construction without departing from the spirit and scope of the invention, as defined by the appended claims.

Claims

I claim:

1. A presser foot assembly for a sewing machine, said presser foot assembly comprising a support arm terminating in a bifurcated end portion, a pivot pin carried by said end portion, a first sole plate carried by said pivot pin for pivotal movement only relative to said end portion, a second sole plate carried by said pivot pin for pivotal movement and limited movement generally normal to the general plane of said second sole plate, and cooperating means on said first and second sole plates restricting relative movement between said first and second sole plates, said cooperating means including said first sole plate having an upper ledge overlying said second sole plate, and resilient means between said ledge and second sole plate constantly urging said second sole plate towards a work engaging position.

2. The presser foot assembly of claim 1 wherein said resilient means include springs disposed on opposite sides of said pivot pin.

3. The presser foot assembly of claim 1 together with a lower ledge on said first sole plate cooperating with said second sole plate limiting downward movement of said second sole plate in response to urging of said resilient means.

4. The presser foot assembly of claim 1 wherein said cooperating means include coacting portions of said first and second sole plates in alignment with said pivot pin substantially filling the space within said bifurcated end portion along said pivot pin thereby assuring positioning of said first and second sole plates axially of said pivot pin.