US3792675A - Presser foot for sewing machine - Google Patents

Abstract

A presser foot for a zigzag sewing machine for preventing the skipping of stitches in the sewing of fabrics. The presser foot is provided with a generally rectangular needle aperture having its major axis extending transversely of the movement of the fabric. The elongated front edge of the aperture has a lip preferably formed of plastic material and extending rearwardly in close proximity to the needle.

Description

United States Patent [191 Kuromegawa [4 1 Feb. 19, 1974 i 1 PRESSER FOOT FOR SEWING MACHINE [75] Inventor:

[73] Assignee: Maruzen Sewing Machine Co., Ltd.,

Osaka, Japan [22] Filed: Apr. 27, 1972 [21] Appl. No.: 248,216

Toru Kuromegawa, Osaka, Japan [52] US. Cl. 112/235 [51] Int. Cl D05b 29/00 [58] Field of Search... 112/235, 236, 237, 238, 239, 1l2/240,157,158,159,150,151,140;

[56] References Cited UNITED STATES PATENTS 2,017,317 10/1935 Magney 74/104 2,811,124 10/1957 Bono 112/235 2,985,126 5/1961 Rhodes 112/235 3,326,159 6/1967 Boser 112/235 3,449,970 6/1969 Klatt 74/89 3,512,490 5/1970 Wener 112/235 FOREIGN PATENTS OR APPLICATIONS 260,273 3/1949 Switzerland 112/235 Primary Examiner-Jordan Franklin Assistant Examiner-Peter Nerbun Attorney, Agent, or Firm-Nathan N. Kraus; Joseph R. Marcus; Gerald S. Schur [5 7 ABSTRACT A presser foot for a zigzag sewing machine for preventing the skipping of stitches in the sewing of fabrics. The presser foot is provided with a generally rectangular needle aperture having its major axis extending transversely of the movement of the fabric. The elongated front edge of the aperture has a lip preferably formed of plastic material and extending rearwardly in close proximity to the needle.

8 Claims, 10 Drawing Figures PAIENIEBFEBIBJQH v 3.792.675

' sum 30F 4 v PATENIEBFEBI 91m SHEET '4 BF 4 BACKGROUND OF THE INVENTION The present invention relates to an improved presser foot for use in a zigzag sewing machine for preventing the skipping of stitches in the sewing of fabrics.

The sewing of modern synthetic soft and flexible fabrics such as polyester knits, and the like, has been attended with problems, in particular, the skipping of stitches during normal operation of the sewing machine. It is believed that this condition is due to a combination of factors, one of which is the relatively large area of the needle hole normally provided in the needle plate and presser foot to accommodate the lateral zigzag movement of the needle. In its downward travel the needle penetrates the fabric and the friction between the needle and the fabric forces that portion of the fabric disposed over the needle hole downwardly into the hole in the needle plate. In the upward travel of the needle the fabric is drawn into the needle hole of the presser foot. Thus, the fabric is caused to flex in the zone of the needle hole. Accordingly, the fabric moves upwardly with the needle instead of lying flat and permitting the needle to move relative to the fabric. As a result the thread passing through the fabric is not subjected to the normal friction which is depended upon to form a proper loop for engagement by the shuttle hook. The consequence is a skipped stitch.

l have found that the problem may be remedied by preventing the upward movement of the fabric into the needle hole of the presser foot as the needle is caused to move upwardly. Thus, the required friction between the fabric and the thread is established to form a proper loop for engagement with the shuttle hook. It is suggested that a simple expedient would be to make the width of the needle hole and the needle plate and in the presser foot approximately equal to the diameter of the needle. Then, fabric could not enter into the needle hole of the presser foot as the needle traveled upwardly because of the relatively close fit between the needle and the presser foot. This arrangement has obvious disadvantages. Because of existing fabrication and assembly tolerances of the machine, the needle is likely to strike the presser foot in its downward movement. Further, when the presser foot is caused to be tilted, as when moving over a seam having double plies of fabric, the needle may strike the edge of the needle hole of the presser foot and be broken.

SUMMARY OF THE INVENTION One of the objects of this invention is the provision in a zigzag sewing machine of means for preventing the skipping of stitches in the sewing of certain types of textile fabrics.

Another object of this invention is the provision of means for preventing the fabric being raised with the upward travel of the needle thereby to insure the formation of a proper loop of the upper thread so that it may be engaged by the shuttle hook.

Still another object of this invention is the provision of a presser foot having an integral lip of reduced thickness extending towards the center line of the needle hole, the fabric engaging portion of the presser foot being molded preferably of plastic material.

A further object of this invention is the provision of a presser foot embodying the foregoing characteristics which includes adjustable means for accurately locating the needle hole in desired registration with the needle so as to preclude the possibility of breakage of the needle.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. l is a fragmentary perspective view of a conventional zigzag sewing machine with certain parts removed to show the underlying structure.

FIG. 2 is a fragmentary vertical cross-sectional view illustrating the sewing condition which obtains when using a conventional presser foot.

FIG. 3 is a similar view illustrating the sewing condition which obtains when using a presser foot in accordance with my invention.

FIG. 4 is a cross-sectional view on a reduced scale taken substantially on line 44 of FIG. 3.

FIG. 5 is an elevational view, partly in cross-section, showing the relationship of the presser foot to the needle when the presser foot is in normal and inclined positions.

FIG. 6 is a fragmentary elevational view of a sewing machine illustrating a modified embodiment of my invention.

FIG. 7 is a cross-sectional view taken substantially on line 77 of FIG. 6.

FIG. 8 is a fragmentary elevational view partly in cross-section illustrating another modified embodiment of my invention.

FIG. 9 is a cross-sectional view taken substantially on line 99 of FIG. 8, and

FIG. 10 is a view similar to FIG. 8 and showing another modified embodiment of my invention.

BRIEF DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, the numeral 12 indicates the arm of a conventional zigzag sewing machine provided with a reciprocating needle bar 11 carried on a supporting member 13 which is arranged to swing laterally of the direction of movement of the fabric being stitched. The needle bar 11 carries a needle 14 secured thereto as with a screw. Supported in the arm 12 for vertical movement is a presser bar 15 which is biased by a coiled compression spring 16 in a downward direction. A pressure foot 17 having a shank 18 is secured to the lower end of the presser bar 15, as with a screw 19. Pivotally secured to the shank 18 as by a pin 21 is a foot member 20 formed preferably of suitable molded plastic material and including an elongated needle hole 22. It will be understood that the length of the hole 22 is sufficient to accommodate the full lateral movement of the needle 14 on opposite sides of a median line. The width of the needle hole 22 conventionally is of the order of l 10th of an inch so that there is sufficient clearance to accommodate the needle to prevent contact of the needle with any part of the foot member. This clearance takes into account any manufacturing and assembling tolerances of the sewing machine parts.

Referring to FIG. 3 the fabric engaging surface 24 of the foot member is provided with a surface portion 23 which extends across the length of the needle hole 22 and rearwardly of the edge 31. The beveled surface portion 23 affords clearance or relief so that there is no pressure on the thread by the foot member in the area immediately rearwardly of the needle hole. Thus, there is no interference with the thread tightening action resulting in improved stitch formation. The foot member includes a lip which as seen clearly in FIG. 3 is integrally molded with the forward edge of the needle hole 22 and extends substantially fully along the length thereof. It will be seen that the lip 25 is integral with the lower portion of the edge 26 of the needle hole and of substantially less depth than that of the foot member 20. Thus, as seen in FIG. 3 there is clearance above the lip 25 for a purpose as will be hereinafter explained. The bottom face of the lip 25 is co-planar with the bottom face of the foot member 20 and constitutes an extension of the fabric pressing surface. As seen in FIG. 3 the lefthand edge of the lip 25 terminates just short of contact with the needle 14 but slightly overlaps a portion of the needle hole in the plate 32. In one example of the present embodiment utilizing a size 14 needle having a diameter of l/20th of an inch, the lip 25 is spaced approximately 1/ 100th of an inch from the needle 14.

The advantages of the present invention will best be understood by reference to FIGS. 2 and 3 which illustrate the prior conditions of operation compared to those accomplished with the present invention.

In the prior art conventional arrangement illustrated in FIG. 2 the needle holes both in the needle plate 32 and in the pressure foot 20 are elongated transversely of the direction of the line of stitching in order to accommodate the needle in its zigzag movement. When a soft fabric is being stitched the fabric 27 tends to be pushed by the needle 14 into the hole in the needle plate 32 as the needle moves downwardly to penetrate the fabric. When the needle 14 moves upwardly the fabric portion a tends to move upwardly into the hole 22 of the foot member, in the manner in-dieated in FIG. 2. Correspondingly, the portion of the upper thread 28 which normally would form the loop to be engaged by the shuttle beak moves with the fabric portion a with the result that the loop disappears, as illustrated in FIG. 2, or is reduced to a size which is insufficient to be caught by the shuttle beak 30 to form a stitch. As a result, a stitch is skipped.

Referring to FIG. 3, in accordance with my invention, the lip 25 pressing down on the fabric 27 prevents the fabric from moving upwardly together with the needle 14 into the needle hole 22. Accordingly, the thread 28 forms a proper loop b shown by the broken lines. This loop is ofa conventional size to be engaged by the beak 30 to form a proper stitch.

The reason for the provision of the clearance above lip 25, as shown in FIG. 3, is illustrated clearly in FIG. 5. At the beginning of a stitching sequence or when the pressure foot 20 is caused to pass over a double seam, the presser foot 20 is caused to rock from the solid line position substantially to the dotted line position and the clearance above the lip 25 prevents the needle 14 from striking the pressure foot 20. It will be noted that when the presser foot rocks in the aforedescribed manner, the lip 25 tends to move farther away from the needle 14 to afford additional clearance thereby insuring that the needle will not strike the presser foot with the consequent breakage of the needle. Further, the fact that the lip 25 has a relatively thin cross-section and is formed of a plastic material minimizes the likelihood of breakage of the needle in the event that the needle should accidentally strike the lip 25. In such event only the lip would be slightly injured without breakage of the needle.

Referring to the modified embodiment illustrated in FIGS. 6 and 7, the numeral 103 generally indicates a presser member having a substantially L-shaped bracket 101 which is mounted at the lower end of a presser bar 102 in a conventional manner. The bracket 101 includes a horizontal leg provided with a pair of guide flanges 107 between which is received the horizontal leg of a complementary member 133 to which is pivotally secured a foot member 105, as by pin 106. The arm 104 is provided with an elongated slot 108 through which passes a screw 109 provided with an adjusting nut and, as will be apparent, the member 133 is adjustably movable relative to the bracket 101. The foot member includes an elongated needle hole 110 defined by a lip and a beveled recess 112, all

similar to corresponding parts of the foot member 20,

of the first described embodiment. The lower face 113 of the foot member 105 bears down on the surface of the fabric 114.

This embodiment affords means for adjusting the foot member 105 in relation to the needle 111 so as to compensate for manufacturing variations and tolerances. Thus, the lip 115 may be accurately positioned in relation to the needle 111 to obtain optimum operating conditions. It will be understood that the foot member 105 functions identically as the foot member 20 of the first described embodiment and is preferably formed of plastic material.

In a second modified embodiment illustrated in FIGS. 8 and 9 the numeral 201 indicates a shank member shaped substantially as illustrated and having means by which it may be conventionally attached to a presser bar 202. The lower end of the shank 201 is received between two upstanding lugs 204 integral with the foot member 203. The lugs 204 are transversely pierced to rotatably receive a shaft indicated generally by 205. Said shaft includes a cylindrical portion 206, an intermediate eccentric portion 207, and an end threaded portion 208, with the portions 206 and 208 being coaxial. As seen in FIG. 9 the eccentric portion 207 is received in an aperture provided in the lower end portion of shank 201. The shaft 205 is provided with a knurled knob 209 and a nut 210 cooperating with the threaded portion of the shaft 208. The foot member 203 similarly to the foot members of the above described embodiments, is formed preferably of molded plastic material and includes an integral lip 213 and an elongated needle aperture 212. It will be apparent that upon loosening of nut 210 rotation of the shaft 205 by means of the knob 209 will effect movement of the foot member 203 to adjust the position of the lip 213 in relation to the needle 211, thereby to compensate for manufacturing variations in the machine.

In another modified embodiment illustrated in FIG. 10, a shank 302 is adapted to be attached to a presser bar 301 in a conventional manner. The shank includes a downwardly extending leg 300 carrying a laterally extending pin 305 on which is pivotally supported a shank portion 304 to which is pivotally connected a foot member 306, as by a pin 307. The shank portion 304 is provided with an arcuate slot 309 which is in registration with an aperture in the shank 302. A screw 308 passed through the aperture and slot is provided with a nut to secure the leg 304 to the shank 302 in a position of adjustment. The foot member 306 is provided with an integral lip 311 and a needle hole 310. It will be understood that the adjustment of the lip 311 in relation to the needle 312 may be effected by first loosening the screw 308, making an adjustment, and then tightening the same.

Each of the modified embodiments hereinabove described provides means for effecting an adjustment of the foot member so as to position the lip as close as possible to the needle, yet affording a minimum clearance so that the needle may not strike the lip.

Various changes coming within the spirit of my invention may suggest themselves to those skilled in the art; hence, we do not wish to be limited to the specific embodiments shown and described or uses mentioned, but intend the same to be merely exemplary, the scope of my invention being limited only by the appended claims.

I claim:

1. In a zigzag sewing machine having a thread carrying needle mounted for endwise reciprocation and for sidewise movement transversely of the direction of reciprocation and a presser bar carrying a presser foot having an elongated needle hole extending in directions transversely of the line of stitching and a medial slot in the forward portion of the foot communicating with the needle hole, the improvement which comprises a lip on said presser foot in one piece with said foot, said lip extending along the forward edge defining said needle hole, the continuity of said lip being interrupted. by said slot, the lower surface of said lip being substantially coplanar with the face of the foot engaging the fabric and constituting an extension of said face, said lip terminating just short of contact with the needle and having a thickness which is less than that of the presser foot, said lip being disposed in sufficiently close proximity to said needle when the same has penetrated the fabric to me clude the fabric being drawn into said hole in the course of the upward movement of the needle thereby to permit the thread to form a loop for proper stitch formation.

2. The invention as defined in claim 1 in which at least the lip is formed of synthetic plastic material.

3. The invention as defined in claim 1 in which the face of the presser foot is recessed in the area adjacent the rearward edge defining the needle hole.

4. The invention as defined in claim 1 including means for adjusting the position of the lip in relation to the needle.

5. The invention as defined in claim 4 in which the adjusting means includes relatively movable members intermediate the presser bar and the presser foot.

6. The invention as defined in claim 4 in which the adjusting means includes a pair of generally L-shaped members, one attached to said presser bar and the other to said presser foot, each of said members having a rearwardly extending leg with said legs being juxtaposed but being relatively movable and means for clamping said legs together in a position of adjustment.

7. The invention as defined in claim 4 in which the adjusting means includes a member attached at its upper end to said presser bar and attached at its lower end to said presser foot by means ofa pin having an ec centric cylindrical portion, the rotation of said pin effecting movement of said presser foot.

8. The invention as defined in claim 4 in which the adjusting means includes a pair of members, one attached to said presser bar and the other to said presser foot, said members being in juxtaposition with one member being pivotally movable relative to the other and means for clamping said members in a position of adjustment.

Claims (8)

1. In a zigzag sewing machine having a thread carrying needle mounted for endwise reciprocation and for sidewise movement transversely of the direction of reciprocation and a presser bar carrying a presser foot having an elongated needle hole extending in directions transversely of the line of stitching and a medial slot in the forward portion of the foot communicating with the needle hole, the improvement which comprises a lip on said presser foot in one piece with said foot, said lip extending along the forward edge defining said needle hole, the continuity of said lip being interrupted by said slot, the lower surface of said lip being substantially coplanar with the face of the foot engaging the fabric and constituting an extension of said face, said lip terminating just short of contact with the needle and having a thickness which is less than that of the presser foot, said lip being disposed in sufficiently close proximity to said needle when the same has penetrated the fabric to preclude the fabric being drawn into said hole in the course of the upward movement of the needle thereby to permit the thread to form a loop for proper stitch formation.

2. The invention as defined in claim 1 in which at least the lip is formed of synthetic plastic material.

3. The invention as defined in claim 1 in which the face of the presser foot is recessed in the area adjacent the rearward edge defining the needle hole.

4. The invention as defined in claim 1 including means for adjusting the position of the lip in relation to the needle.

5. The invention as defined in claim 4 in which the adjusting means includes relatively movable members intermediate the presser bar and the presser foot.

6. The invention as defined in claim 4 in which the adjusting means includes a pair of generally L-shaped members, one attached to said presser bar and the other to said presser foot, each of said members having a rearwardly extending leg with said legs being juxtaposed but being relatively movable and means for clamping said legs together in a position of adjustment.

7. The invention as defined in claim 4 in which the adjusting means includes a member attached at its upper end to said presser bar and attached at its lower end to said presser foot by means of a pin having an eccentric cylindrical portion, the rotation of said pin effecting movement of said presser foot.

8. The invention as defined in claim 4 in which the adjusting means includes a pair of members, one attached to said presser bar and the other to said presser foot, said members being in juxtaposition with one member being pivotally movable relative to the other and means for clamping said members in a position of adjustment.

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