US2694993A - Presser-foot for sewing machines - Google Patents

Description

Nov. 23, 1954 H. J. GOOSMAN 2,694,993 PRESSER-FOOT FOR SEWING MACHINES Fiied April 21, 1953 2 Sheets-Sheet l i A w INVENTOR. gfe ew'i oosmam WITNESS, y 9 M w A ATTORNEY Nov. 23, 1954 H. J. GOOSMAN 2,694,993

PRESSER'FOOT FOR SEWING MACHINES Filed April 21, 1 953 2 Sheets-Sheet 2 IN V EN T 0R. fevbew'fi goosma'm WITNESS wy d BY ATTORNEY United States Patent PRESSER-FOOT FOR SEWING MACHINES Herbert I. Goosman, Watchung, N. 1., assignor to The Singer Manufacturing Company, Elizabeth, N. J., a corporation of New Jersey Application April 21, 1953, Serial No. 350,094

4 Claims. (Cl. 112-235) tionary presser-foot is disposed at one side of the fabric plies being stitched and is biased in opposition to a movable work-feeding member disposed at the opposite side of the Work. 1

In this type of sewing machine, since the feeding movement of all of the fabric plies is derived solely from movement of the feed member at one side of the work, the drag exerted by the stationary presser-foot sole-plate upon the ply or plies engaged thereby must be minimized or else the ply or plies, which are influenced by this dragging action of the presser-foot, will be retarded and an uneven or puckered seam will be made. Heretofore, for the purpose of reducing the frictional forces between the presser-foot and the fabric, it has been the practice to provide the work-engaging portions of presser-feet with flat, smooth surfaces and to apply a plating to these surfaces which will sustain a high polish.

While such smooth and polished presser-foot sole-plate surfaces operate satisfactorily in most cases when the usual woven or knit fabrics are being stitched, they are not well suited for proper handling of the more recently developed plastic sheet materials. These plastic materials tend to adhere to a smooth polished presser-foot soleplate so that resistance to continued motion soon builds up greatly in excess of the normal frictional forces which exist between the two surfaces. This adhesion is apparently caused by a static electrical charge which is induced by the relative motion between the material and the soleplate. The adhesion may also be caused by the wiping of air from between the contacting surfaces so that the plastic material clings to the presser-foot sole-plate in much the same fashion as a suction cup.

The problem of adhesion of plastic sheet materials to work-guide surfaces has received considerable attention by others, reference being made to the patent of Sailer, No. 2,514,013, July 4, 1950. In the Sailer patent, the guide surfaces are provided with a myriad of small raised islands which reduce the guide surface which is in contact with the plastic material by approximately 80%. With fabric guides no pressure other than the weight and normal action of the fabric itself is used to force the fabric against the guide surfaces. The fabric, therefore, moves in contact with only the tops of the raised islands. With presser-feet, however, the sole-plate is forced against the fabric with a pressure of such a magnitude that the Sailer concept of a myriad of raised islands would be practically inoperative because the islands would be pressed into the fabric and the consequent increase in the normal frictional forces would far exceed any possible reduction in adhesive effect.

It is a primary object of this invention to provide a presser-foot sole-plate construction with which plastic sheet materials and the like may be fed through a sewing machine without objectionable puckering and gathering. To this end instead of a smooth flat presser-foot sole-plate, a sole-plate construction is employed in which the entire work-engaging surface is formed with uneven ridges which act upon the work to minimize the objectionable frictional forces which are usually experienced when plastic fabrics are being stitched.

The only instances in the prior art, to my knowledge, in which smooth and polished presser-foot sole-plate surfaces have not been resorted to, are those in which the retardation action of the presser-foot is to be purposely 2,694,993 Patented Nov. 23, 1954- induced, as in the production of ruffled or gathered seams or the like. It is a more specific object of this invention to provide a novel form and arrangement of sole plate ridges which will effect a reduction in the frictional drag when utilized with plastic sheet materials.

The above and other objects and advantages of this invention will be apparent from the following description and accompanying drawings of a preferred embodiment thereof in which:

Fig. 1 is a fragmentary end elevational view of a sewing machine having the presser-foot of this invention applied thereto.

Fig. 2 is a top plan view of a portion of the sewing machine of Fig. 1.

Fig. 3 is a bottom plan view of the presser-foot.

Fig. 4 is a cross-sectional view taken substantially along line 4-4 of Fig. 3.

Fig. 5 is a cross sectional view taken substantially along line 5-5 of Fig. 3.

The presser-foot of this invention is shown as applied to an overedge sewing machine of the type disclosed in the Knaus Patents No. 2,238,796, April 15, 1941, and No. 2,419,494, April 22, 1947. Insofar as is pertinent to the present invention, the sewing machine comprises a frame 10 upon which is pivotally mounted a work-supporting plate 11 formed to embrace a throat-plate 12 that is carried by the frame.

A curved needle 13 carried by a rock-arm 14 is actuated by a rock-shaft 15 journaled in the frame. Cooperating with the needle in the formation of overedge chainstitches is an under or needle-loop taking looper 16 and an overedge looper 17.

The work-feeding mechanism is of the four motion type, i. e., a feed-dog 20 is lifted to extend through suitable slots formed in the throat-plate and when lifted is advanced to feed the work in the direction indicated by the arrow in Fig. 2. The feed-dog is then lowered beneath the throat-plate and returned to complete a feeding cycle. The feed-dog 20 is carried by a feed-bar 21 which is slidably pivoted on a block pivotally secured at 22 to the frame. Rising and falling movements are imparted to the feed-dog by means of a lift eccentric 23 which is fast on a main shaft 24 journaled in the frame 10. Embracing the lift eccentric 23 is a slide block 25 which is slidable in ways 2626 formed in the feed-bar Advance and return movements are imparted by means of an advance eccentric 27 fast on the main shaft, which is embraced by a pitman 28 that is pivoted to the feed-bar at 29.

Opposed to the fed-dog 20 and the throat-plate 12 is a presser-foot 30 which is pivotally secured to a substantially horizontal presser-bar 31. The presser-bar is secured to the frame by means of a universal connection by which the presser-foot may be moved vertically to permit work to be introduced thereunder and also to be swung out laterally to give access to the stitch-forming instrumentalities. The universal connection comprises a yoke 32 journaled on a horizontal stud 33 secured in the frame and to which the Presser-bar is pivoted by the vertically arranged stud 34.

The presser-bar and the presser-foot carried thereby are urged downwardly into operative work-engaging position by a spring-pressed plunger 40 which is journaled in a tubular extension 41 of the frame 10 and is biased downwardly against the presser-bar by means of a coil spring 42.

The under or work-engaging portion of the presser-foot 30 is termed the sole-plate, and as best illustrated in Figs. 3, 4 and 5, includes preferably an upturned toe portion 51 and a heel portion 52. The sole-plate is formed with an irregular surface conformation which has been found to be highly effective in reduced the adhesive effect usually experienced when sewing plastic sheet materials without appreciably increasing the normal frictional forces.

In the preferred embodiment of this invention, the soleplate is formed with a series of similar laterally spaced sinuous flutes 55, the mean direction of each flute being from the toe to the heel portion and substantially parallel to the direction of stitch formation of the sewing machine, as indicated by the arrow in Fig. 2 when the presser-foot is located in operative position. Alternate flutes are oifset longitudinally to a position completely out of phase with' each adjacent flute so as to divide the sole-plate into a series of laterally spaced hour glass-shaped ridges or lands 56 varying along their length in bothv breadth and height in converse relation with the adjacent ridges at each side. By this it is meant that the'adjacentridges arestaggered in a manner identical with that of the flutes i. e. the widest portions of each ridge are located in nested fashion opposite the narrowest portions of each adjacent r1 ge.

It will be appreciated that the spring pressure which urges the presser-foot downwardly will force the soleplate tightly into engagement with the fabric'being stitched and will result in substantially continuous contact of the fabric with all points on the presser-foot sole-plate in cluding the bottoms of'the shallow flutes. The nested arrangement of the irregularly shaped ridges appears to have a kneading effect upon plastic sheet fabrics which are fed thereunder by which the objectionably adhesive effect which is normally experienced when sewing such fabrics is greatly reduced.

Having thus set forth the nature of the invention, what I claim herein is:

1'. In a sewing machine having a frame, a plate carried by said frame and having a work-engaging surface formed thereon, and a presser-foot having a work-engaging surface biased in opposition to said work-engaging surface of said plate, at least one of said Work-engaging surfaces being provided with a plurality of substantially parallel ridges, each of said ridges varying continuously along its length in both breadth and height in converse relation with the adjacent ridges ateaehside.

2. A sewing machine presser-foot having a work-engaging sole-plate, corrugations formed in said work-engaging sole-plate providing a plurality of substantially parallel ridges, each of said ridges varying continuously along its length in both breadth and height in converse relation with the adjacent ridges at each side.

3. A presser-foot for a sewing machine presser-device of the type having means yieldingly biasing said presserfoot into operative Work-engaging position, a work-engaging' sole-plate formed on said presser-foot having a toe and a heel portion, said sole-plate being formed with a plurality of sinuous flutes. extending from said toe to said heiel portion and defining a series of irregularly shaped r1 ges.

4. In a sewing machine having a work-feeding member, a presser device including a work-engaging sole-plate having alongitudinal axis substantially parallel to the direction of work feed, and spring means biasing said soleplate into opposed relation to said work-feeding member, said sole-plate being formed with a plurality of longitudinally extending sinuous flutes defining a plurality of spaced ridges having varying width along said longitudinal axis.

References Cited in the file of this patent UNITED STATES PATENTS Number

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