US2977913A

US2977913A - Method of sewing parallel rows of zigzag stitches

Info

Publication number: US2977913A
Application number: US640035A
Authority: US
Inventors: Schenkengel Emerich
Original assignee: GM Pfaff AG
Current assignee: GM Pfaff AG
Priority date: 1956-02-17
Filing date: 1957-02-13
Publication date: 1961-04-04
Anticipated expiration: 1978-04-04
Also published as: FR1160553A

Description

April 4, 1961 5 SCHENKENGEL 2,977,913

METHOD OF SEWING PARALLEL ROWS 0F ZIG-ZAG STITCHES Filed Feb. 15, 1957 F/GB A TEE/V5) METHOD OF SEWING PARALLEL ROWS OF ZIG- ZAG STITCHES Emerich Schenkengel, Kaiserslautern, Pfalz, Germany, assignor to G. M. Pfaif A.G., Kaiserslautern, Pfalz, Germany, a corporation of Germany Filed Feb. 13, 1957, Ser. No. 640,035 Claims priority, application Germany Feb. 17, 1956 5 Claims. (Cl. 112-264) The present invention relates to an improved method of and means for sewing parallel rows or lines of zig-Zag stitches by the aid of zig-zag sewing machines, such as required in the sewing of button holes, ornamental designs, etc. including at least one pair of parallel rows or lines of zig-zag stitches or patterns.

While the invention will be described in the following with specific reference to the sewing of button holes, it will be evident that the improved features and steps may be used with equal advantage in connection with other sewing operations involving the production of two or more rows of zig-zag lock stitches.

Conventional zig-zag stitch button hole sewing machines, as described, for instance, by US. Patent Nos.

' hole stitch-es,

If the lines of zig-zag stitches of a button hole'of this I type are produced in the usual manner by first sewing one row of zig-zag side stitches in one direction and subsequently sewing the adjacent row of side stitches in the opposite direction, uponreversal of the stitching direction and lateral displacement of the middle stitching position or line, it is found that the reverse stitching line or pattern, while marked by its exact parallelism with the forward stitches is less perfect and satisfactory from an appearance point of view compared with the forward stitches, thereby distinguishing button holes fabricated mechanically by machines from manually sewn button holes which are characterized by the uniformity of the structure and appearance of both side stitches.

One method to avoid the above-mentioned disadvantage consists in reversing the work or material by 180 upon completion of the first zig-zag side stitch, a procedure being highly cumbersome and impractical, especially in caseof relatively large work pieces or sizes of sewing material. i t

Another method to overcome the above-mentioned difficulty consistsin lifting the work clamp or presser foot upon completion ofgthe first. zig-zag side stitch and to pull back the work to the starting" point of thesecond side stitch to be sewn parallel to and in the same direction as the first side stitch of the button hole. This solution again results in an'impairrnent'of the appearance of the stitches or final button holeas well as in other difficulties i Accordingly, an object. of the present invention is'the: provision of an improved method 0f and means for pro-' 2,977,913 Patented Apr. 4, 1961 ducing parallel rows or lines of zig-zag stitches by means of zig-zag sewing machines, whereby the above and related difficulties and drawbacks are substantially avoided.

Another object of the invention is the provision of an improved method-of and means for producing parallel rows or lines of zig-zag stitches, whereby the individual lines are characterized both by an exact parallelism as well as by an equal structure and appearance of the stitches. 7

Yet another object of the invention is the provision of a novel method of and means to enable the fabrication of parallel zig-zag stitches without displacement of the work and the additional labor and other disadvantages connected therewith.

Still another object of the invention is the provision of presser foot guide means for use in connection with a zig-zag sewing machine for carrying into effect the method according to the invention, especially for the sewing of raised zig-zag stitches in the fabrication of button holes and the like. 7

The invention, as to its further objects and novel aspects, will be better understood from the following detailed description taken in reference to the accompanying drawing, forming part of this specification and wherein:

Figs. 1' to 4 are diagrammatic representations of stitchesproduced during the successive steps of the improved method according to the invention; and 7 Figs. 5 and 6 are elevational and bottom views, respectively, of an improved presser foot construction being especially suitable in the fabrication of button holes comprising raised zig-zag stitches made by the method according to the present invention. 7

With the foregoing objects in view, the improved method according to the invention, with specific reference to the sewing of button holes, involves generally the stepsof sewing a first zig-zag side stitch in one direction, such as the foreward operating direction of the machine, laterally displacing the stitching position or medial stitching line by a distance equal to the required spacing distance between the parallel side stitches of the button hole and subsequently sewing a line of straight stitches in the opposite or reverse direction of the machine and in parallel to the first line or row ofside stitches. As a result, the needle, upon completion of the straight stitches or seam will be in a position for starting the sewing of the second line of zig zag side stitches in the same direc-.

tion and parallel to the first line of side stitches of the button hole during the third or final step of the buttonhole sewing cycle or operation. In other words, the second line of zig-zag side stitches is symmetrical to and overlies the seam or line of straightstitches produced during the reverse operation of the machine. This not only insures a perfect parallelism between the side stitches of the button hole, but furthermore results in a uniformity of both side stitches both as to structure and appearance. Practice has shown that a line of zig-zag stitches sewn over a' line of straight stitches does not visiblydiffer from a simple line of zig-zag stitches sewn .without underlying straight stitches, provided ordinary thread is used for both the straight and zig-zag stitches; After both side stitches have been completed, the material between the closely adjoining stitches is slit by the operation of the button hole cutting mechanism in the usual manner. The ends of the side stitches may be joined by barring zig-zag stitches of greater width extending across both side stitches, in a manner described in greater detail hereafter. j

While sewing the secondside stitch, it is necessary to pass the previously completed first side stitch underneath the 'presser foot or work;.clamp of the machine. In order to facilitate this operation and to properly guide the 'work, especially when producing raised stitches or 3 patterns characterized by their pleasing appearance, the presser foot, according to an improved feature of the invention, is provided with suitable guide grooves constructed in such a manner as to properly guide the stitches, substantially without interference with the stitch forming operation of the machine.

It has already been proposed to provide a single guide groove in the underface of the presser foot base of a zigzag sewing machine, said groove being subdivided into two shorter grooves or sections close to the needle aperture within said base and said shorter sections being separated from-one another by a central rib or ridge medial to the undivided main section of the groove. Such a presser foot construction is limited in its use to zig-zag sewing machines having a fixed needle position and is unsuitable for use with machines equipped with adjustable needle position as required for the sewing of parallel scams or stitches of either straight or zig-zag shape in carrying into effect the present invention.

The improved presser foot construction according to the present invention substantially overcomes the aforementioned difficulties and defects, whereby to enable the fabrication of both fiat and raised zig-zag stitches or patterns, the latter being especially desirable in the sewing of button holes on account of their better appearance.

To this end, the improved presser foot construction according to the invention comprises essentially a pair of parallel guide grooves extending over the entire width of the base of the foot and being separated by a central rib or ridge medial to or concentric, according to a preferred construction, with the needle aperture within said base. Furthermore, said ridge has a height extending to a point spaced from the bottom or underside of said base, to prevent interference with the operation of the stitch forming mechanism of the machine by allowing the lower thread cooperating with the upper thread in the formation of the lock stitches to be readily extracted or withdrawn, to produce a raised stitching pattern or button hole. In this manner, zig-zag sewing machines having means for adjusting the stitching position may be readily and simply adapted for the sewing of button holes of either the flat or raised type in accordance with the novel method proposed by the present invention.

Referring more particularly to the drawing, Figs. 1 to 4, illustrating the method according to the invention, the numeral 1 diagrammatically shows the first line of zig-zag side stitches of a button hole sewn in the forward operating direction of the machine as indicated by the arrow a, during the first step of a complete button hole sewing cycle or operation' Numeral 2 indicates the straight stitch or seam sewn in the reverse direction as indicated by the arrow b upon completion of the first stitch 1 and lateral shift of the stitching position by a distance d equal to the distance between the medial lines of the final stitches of the completed button hole, Fig. 4. To this end, the machine, upon completion of the first zig-zag stitch 1, is adjusted or converted from zig-zag to straight stitching, this operation as well as the change of the stitching position being carried out either manually or automatically by means well known and readily understood, as shown by the above-mentioned patents. Upon completion of the straight seam 2, the

needle is in a position adjacent to the beginning of the line of side stitches 1, that is, ready to start the third step of sewing the second parallel line of zig-zag side stitches 4 of the button hole in the same or forward direction a as used in sewing the line of stitches 1. For this purpose, the direction of operation of the machine is again reversed at the end of the straight stitch 2. The zig-Zag stitch 4 is thus superimposed upon or overlies the straight seam 2, whereby both side zig-zag stitches 1 and 4- of the button hole'are sewn in the same direction, to result in an exact parallelis'rn'as well as an equal structure and appearance of the stitches, substantially. without the drawbacks and defects of previously known stitching methods and operations. In Fig. 2, the side stitch 4 is shown only partly completed, the complete stitch being shown in Fig. 4.

The ends of both side, stitches 1 and 4 may be joined by barring zig-zag stitches 3 and 5 of greater width and extend across both rows of side stitches, as shown in? Figs. 3 and 4, the former illustrating the barring stitch produced at the completion of the straight stitch 2 and.

prior to the starting of the line of side stitches 4 and Fig. 4 showing the barring stitch sewn at the completion of the line of side stitches 4, to result in a final button hole upon slitting of the narrow space between the

stitches

2 and 4, shown on an exaggerated scale in the drawing, by the button hole cutting mechanism.

As pointed out, the steps of the invention may be carried out manually by the operation the means controlling the sewing direction and zero stitch position, as well as for changing from straight to zig-zag stitching, and for adjusting the width of the zig-zag stitches, all known'per se in connection with conventional zig-zag, as shown by the above-mentioned U.S. patents.

As will be evident, the method of the invention may also be carried into effect mechanically by theuse of a sewing machine equipped with means for automatic stitch position and stitch width control. In machines of this type, the controls are effected by suitable control devices, such as cams etc., a separate control device being provided, for instance, to control the stitch width and stitch position, respectively. Alternatively, a single control device may be employed in an automatically controlled zig-zag sewing machine constructed in a known manner to effect control of both the width and position of the stitches.

More particularly, in the case of button hole sewing machines having automatic means to control the entire operating cycle or button hole sewing operation by means of a cam or the like, the cam initiating the controlling impulses or operations may be so constructed that, after the sewing of the first line of side stitches, a straight seam is sewn in the opposite direction upon laterally shifting of the stitch position, whereupon the sewing direction is again reversed to initiate the sewing of the second line of side stitches, in the manner described and readily understood from the foregoing. The control cam or the like may furthermore be so constructed as to increase the stitch width at the end of the straight seam 2 and zig-zag stitch 4, respectively, to enable the sewing of the barring stitches 3 and 5 at the opposite ends of the button hole. For this purpose, further provision may be made to effect a stitch position control, either manually orautomatically to cause the barring stitches 3 and 5 to be symmetrical to the medial line of the

side stitches

2 and 4 or extend across both ends of the side stitches.

Figs. 5 and 6 show the improved presser foot construction for use in zig-zag sewing machines having means for stitch position control and adapted for practicing the method according to the invention. The presser foot shown, being of conventional construction, comprises an upper. vertical part 6 having an extension 7 for mounting it upon the presser foot bar of the machine. The lower part or base 3 engaging the work in the lowered position has an aperture 11 providing a passageway for the needle indicated at 14'. Provided at the bottom or undersurface 13 of the base 8, in accordance with the improved construction of the present invention, are a pair of parallel guide grooves 9 and 10 extending across said base and being spaced by a separating rib or ridge 12 the ridge 12 separating the grooves 9 and 10 has the effect of preventing interference with the stitching operation of the needle and cooperating stitch forming tools of the machine, whereby to enable the sewing of raised stitches by extraction or ready withdrawal of the lower thread, without interference with the stitch formation and impairment of the structure and appearance of the stitches.

In the foregoing'the invention has been described with reference to a specific illustrative methodrand device. It will be evident, however, that variations and modifications, as well the substitution of equivalent steps and elements for those shown and disclosed for illustration,

may be made without departing from the broader scope and spirit of the invention, as set forth in the appended claims. The specification and drawing are accordingly to be regarded in an illustrative rather than in a limiting sense.

I claim: 1

1. A method of producing parallel zig-zag stitches by a zig-zag sewing machine having means to reverse the stitching direction, to control the middle stitch position and to convert from zig-zag to straight stitching and vice versa, said method comprising the sequential steps of sewing a first line of zig-zag stitches in a predetermined direction, sewing a line of straight stitches in a direction opposite to said predetermined direction and in spaced relation and parallel to said first stitching line, and sewing a third line of zig-zag stitches in said predetermined direction symmetrical to and overlying said straight stitching line. 7

2. A method of sewing button holes by the aid of zig-zag sewing machines having means to reverse the stitching direction, to control the middle stitch position and to convert from zig-zag to straight stitching and vice versa, said method comprising the sequential steps of sewing a first line of zig-zag side stitches in a first direction, sewing a line of straight stitches in a direction opposite to said first direction, and parallel to and spaced from the middle line of said first stitches, sewing a second line of button hole zig-Zag side stitches in said first direction and symmetrical to and overlying said straight stitches, and cutting the intervening material between said first and second lines of zig-zag stitches.

3. A method of sewing button holes of the air of zigzag sewing machines having means to reverse the stitching direction, to control the zigzag width and middle stitch position and to convert from zig-zag to straight stitching and vice versa, said method comprising the sequential steps of sewing a first line of zig-zag side stitches of predetermined width in a first direction, sewing a line of straight stitches in a direction opposite to said first direction and parallel to and spaced from said first stitching line, producing a barring zig-Zag stitch of greater width than said side stitches at the beginning of said first line of side stitches, sewing a second line of zigzag side stitches in said first direction of a width equal to said predetermined width and symmetrical to and overlying said straight stitches, and producing a barring zigzag stitch at the end of said second row of zig-zag side stitches.

4. A method as claimed in claim 3 said steps of producing barring stitches consisting in sewing zig-zag stitches between the outer edges of said first and second line of zig-Zag side stitches.

5. A method of sewing button holes by the aid of zig-zag sewing machines having means to reverse the stitching direction, to control the zigzag width and middle stitch position and to convert from zig-zag to straight stitching and vice versa, said method comprising the sequential steps of sewing a first line of zig-zag side stitches of predetermined width and length and in a predetermined direction, sewing a line of equal length of straight stitches adjacent to said first stitches and in a direction opposite to said predetermined direction and parallel to and spaced from said first stitches, producing a first barring zig-zag stitch of greater width than and located at the beginning of said first stitches, sewing a second line of button hole zig-zag side stitches in said first direction symmetrical to and overlying said straight stitches, producing a second barring zig-zag stitch at the end of said second button hole stitches, said barring stitches extending across the ends of said button hole stitches, and cutting the intervening material between said first and second button hole stitches.

References Qited in the file of this patent UNITED STATES PATENTS 786,934 Woodward Apr. 11, 1905 1,427,197 Egan Aug. 29, 1922 1,483,184 McCann Feb. 12, 1924 1,640,283 Miller Aug. 23, 1927 1,675,508 Muller July 3, 1928 1,699,314 Sieber Jan. 15, 1929 2,151,381 Goldsmith Mar. 21, 1939 2,378,534 Beyer June 19, 1945 2,682,845 Casas Robert et a1. July 6, 1954