US2990793A - Zig-zag sewing machines - Google Patents

Description

July 4, 1961 H. ZINK EI'AL 2,990,793

ZIG-ZAG SEWING MACHINES Filed July 12, 1955 4 Sheets-Sheet 1 V/NI/ENI'OPS July 4, 1961 H. ZINK EI'AL ZIG-ZAG SEWING MACHINES Filed July 12, 1955 4 Sheets- Sheet 2 INVENTOPS Hermann Z "V" Herbal-f h/E/VZ I/eIhr/cb .BUNGEPT' July 4, 1961 H. ZINK EI'AL ZIG-ZA G SEWING MACHINES 4 Sheets-Sheet 3 Filed July 12, 1955 //V VE N 7' 0/75 firmnnn Z/NK fkrber f WENZ Heinrich BUNGEPT July 4, 1961 H. ZINK ETAL 2,990,793

ZIG-ZAG SEWING MACHINES Filed July 12. 1955 4 SheetsSheet 4 INVENTORS HERMANN ZINK HERBERT WENZ HEINRICH BUNGERT BY W" ATTORNEY United States Patent 2,990,793 ZIG-ZAG SEWING MACHINES Hermann Zink, Herbert Wenz, and Heinrich Bungert, Kaiserslautern, Germany, assignors to G. M. Pfatf A.-G., Kaiserslautern, Pfalz, Germany, a joint-stock company of Germany Filed July 12, 1955, Ser. No. 521,541 2'Claims. (Cl. 112-158) The present invention relates to a device for adjusting and limiting the stitch width in zig-zag sewing machines.

In the sewing of buttonholes, which may be performed in sig-zag sewing machines having means for adjusting the width of the zigzag stitch, there is the special problem of having to produce alternately a tacking or narrow stitch and an overstitch or wide stitch, the latter being of double width relatively to the narrow stitch. The devices hitherto known for such purposes have only a limited number of possible positive adjustments from which a selection may be made, or the adjustments must be made by means of a scale and pointer. In the latter case, not only must the adjustment value he observed whilst changing the stitch width but also the indicator must always be aligned with the selected strokes on the scale.

The primary object of the present invention is to produce a stitch adjusting device which makes it possible not only to select any desired width of stitch but also, in cases where a narrow stitch and a wide stitch are associated in a selected fixed ratio, as for buttonhole sewing, permits of the selection of any value for the width of the narrow stitch and thereby automatically selecting the width of the wide stitch.

The accompanying drawings illustrate two embodiments of a device according to the present invention by way of example. In the drawings:

FIG. 1 is a representation of a zig-zag sewing machine fitted with the new device;

FIG. 2 illustrates a portion of the machine arm with a front view of the fitted device, omitting the fronts of the arm and cover, as also the displacement mechanism of the connecting link and the fork bar;

FIG. 3 is a plan view of a portion of the machine arm without the cover and with the fitted device;

FIG. 4 is a section through the machine arm viewed in the direction of the hand wheel;

FIG. 5 is the limiting member shown in perspective;

FIG. 6 is a perspective view on a part of the construction of FIG. 4, on a larger scale;

FIGS. 7 and 8 illustrate a simplified form of a device constructed according to the invention, but modified relatively to the embodiment shown in FIGS. 2-6, and with the individual members dismantled and shown in perspective, FIG. 7 being a front view but FIG. 8 a rear view of the parts, the latter omitting the notched plate for the adjustment of the stitch position; and

FIG. 9 is a fragmentary view of the scale plate shown in FIG. 7, the recess with the stop projection being shown magnified;

FIG. 10 is a schematic elevational view of some of the parts of the embodiment of FIGS. 2-6, with the limiting member in its lowest position affording maximum amplitude of movement for the stop lever between the two tracks of the limiting member;

FIG. 11 is a schematic elevational view similar to FIG. 10, but showing the limiting member in its highest position for minimum amplitude of the stop lever; and

FIG. 12 is an extended view, in perspective, of some of the parts for needle and zig-zag operations, and for control in accordance with the instant invention.

In the drawings, 1 is the machine arm in which there is journalled the arm shaft or top shaft 2 which actuates a needle bar 87 (FIG. 12) and, through a pair of bevel gear wheels 3, 4 operates a cam 5 to actuate a forked guide lever 6. The forked guide lever 6 has an extension 83 which is pivoted by a bolt 84 to a tiltable guide 86 for the needle bar 87. The tiltable guide 86 is swingable about a horizontal pin 85, for zig-Zag stitching. The forked lever 6 has a pin on which there is journalled a sliding block 7. The sliding block 7 is slidably guided in a guide slot 88 that is formed eccentrically in a head 8 of a bolt 9. The bolt 9 is journalled in an arm of a lever 11 which is pivoted on a spindle 12 that is parallel to the bolt 9. The lever 11, and thereby the bolt 9, is tiltable about the axis of the spindle 12, and the position of tilting of the lever 11 determines the position of the stitch line.

In the embodiment of the device shown in FIGS. 2-6, there is provided a threaded bearing sleeve 13 that is mounted on the machine arm 1. A bushing 14 which has an outer thread in threaded engagement with the sleeve 13 is displaceable axially in said sleeve 13 by turning of the bushing 14. A limiting member 15 has a pivot in the form of a set screw 16 which is mounted in the bushing 14. A knurled or milled control disc 17 is disposed on the bearing sleeve 13 and mounts in its bore a projection 18 which projects into a groove 19 of the bushing 14 so as to rotate the bushing with it. A spring 20 is attached to the machine arm 1 by means of a nut 21 on a screw 22 which secures the spindle 12 and this spring presses by its front bifurcated end against the control disc 17.

The limiting member 15 is provided with two stop tracks 23, 24 and two opposite stop projections 25, 26. A spring mounted pivoted lever 27 is displaceably attached to the limiting member 15 and may engage selectively in either of two recesses 28, 29 in the machine arm 1. A stitch adjusting member 30 is journalled about the spindle 12 and carries a stop lever 31 which includes an upper abutment point 32 for engaging the stop track 23 and a lower abutment point 33 for engaging the stop track 24. An adjusting lever 34 of the stitch adjusting member 30 is connected by way of a hinged transmission lever 35 to a pin 36 that is mounted in the adjusting knob 10. Another lever 37 of the member 30 is linked by way of a connecting rod 38 to any known device for actuating the stitch varying means, for instance a knee-' actuated lever or a foot treadle, thus enabling member 30 to be operated without using the hands.

The manner of operation of the device described and shown with reference to FIGS. 2 6 is as follows:

The adjusting knob 10 for the stitch width is in zero position (straight stitch) when rotated clockwise to the fullest extent, the top lever 31 then being in its highest position. If the limiting member 15'- is now rotated about the axis of the set screw 16 for a fraction of a full turn by the engagement of the pivoted lever 27 in the recess 28', only the stop track 24 projects into the path of movement of the stop lever 31. If now the limiting mem ber 15 has been brought into its lowest position by turning of the control disk 17 manually, the entire range of adjustment of the knob 10' is then opened for voluntary selection and variation, up to the limit of the greatest stitch width, with the greatest counterclockwise deflection of the knob 10 and simultaneously the lowest position of the stop lever 31.

The adjustment of the limiting member 15 to a higher position by means of the control disc 17 effects through the stop track 24 a limitation of the movement of the lever 31 and, therefore, of the knob 10 and consequently.

Patented July 4, 1961 position of member 15, it has reached its zero position and the lever 31 is arrested. The device may therefore act as a stop for determining any desired range of width of stitch between a predetermined maximum and minimum value, or as a safety device for the straight stitch.

If the limiting member 15 is now turned back by the engagement of the pivoted lever 27 in the recess 29, its two stop tracks 23- and 24 limit the range of movement of the stop lever 31, the stop track 23 determining the smaller width of stitch and the stop track 24 the larger width thereof. The actual size of the maximum (FIG. and minimum (FIG. 11) stitch widths which are in a fixed ratio to each other, may be selected by the axial displacement of the limiting member 15 by means of the control disc 17. Thus, for example, for buttonhole sewing, only the desired narrow stitch width need be adjusted in order, at the end of the narrow stitch, to have immediately the correct width of the wide stitch by simply turning the knob 10 counterclockwise as far as the stop track 24 will allow and, after the wide stitch, to have again the original narrow stitch width by merely turning back the knob 10 as far as the stop track 23 will allow.

As soon as the second narrow stitch and the second wide stitch have been made, the pivoted lever 27 is brought into the recess 28 and the knob 10, which is thereby released in one direction, into its zero position for the normal straight stitches. The position of the control disc 17 remains unchanged and thus the identical narrow stitch and wide stitch widths may be effected for every buttonhole of a series by appropriate movement of the pivoted lever 27.

The stop projections 25 and 26 of the limiting member 15 serve to limit the displacement of the member 15 in vertical direction; the upper projection 25 will abut against the disc 17 in the lowest position of the member 15, and the lower projection 26, respectively, in the top position of the member 15.

In the case of the modified embodiment shown in FIGS. 79 a mounting plate 39 provided with notches 41 is secured by attachment holes 40 (FIG. 7) on the machine arm 1. Below the elongated opening 44 for the bolt 9 of the adjusting knob 10 there is provided a guide groove 43 corresponding to the diameter of the pressurespring 42. On a sliding surface 45 formed on the mounting plate 39 there is displaceably located a sliding block 46 which is provided with a stop projection 47, having two guide pins 48 and a spring support 49 bent at right angles into the guide groove 43. Two stops 50 arranged in a line parallel to the guide groove 43 engage in the two guide slots 51 of the scale plate 52 and terminate flush with the surface thereof.

The scale plate 52,- that is provided with the indicator point 53, has at its lower end a recess 54 having two step edges or tracks 55, 56 for controlling a straight stitch and for the limitation of the width of the wide stitch (FIG. 9). A flap 57, bent at right angles into the guide groove 43 is used as a support for the pressure spring 42. Two limiting slots 58 in the scale plate 52 receive the said guide pins 48 of the sliding block 46. An elongated opening 59 for the bolt 9 of the adjusting knob 10 is also provided in the scale plate 52.

The slide 60, provided with an adjustable control abutment element 61 (FIG. 8), is received by two slide guides 62, lying towards the indicator and provided in the adjusting knob 10. The abutment element 61 projects into the recess 54 of the scale plate 52. The bolt 9 of the adjusting knob 10 passes through a slot 63 arranged in the slide 60.

The slot 64 made in the slide 60 receives a pin 67 eccentrically arranged on a collar 65 of an operating spindle 66. The control knob 68 is let into a recess 69 of the adjusting knob 10 and is secured by means of a bore 70 and a set screw 71 to the operating spindle 66 which passes through the aperture 72 of the adjusting knob 10.

The operation of the device according to the embodiment shown in FIGS. 79 is as follows:

The slide 60 may be adjusted in height together with its stop element 61 disposed in the recess 54 by turning the control knob 68 and by the eccentric pin 67, which engages in the slot 64, executing the corresponding adjusting movement. If the slide 60 and consequently its stop element 61 are in the highest position the adjusting knob 10 with the slide 60 arranged therein and the stop element 61 in the recess 54 can execute the greatest rotary movement between the stop edges 55 and 56.

The adjusting knob 10 for the stitch width is in zero position (straight stitch) when it is rotated to the fullest extent clockwise and is set for the greatest possible stitch width adjustment when it is turned farthest counterclockwise.

If the stop element 61 in the recess 54 is downwardly displaced, its path of movement is limited at one end by the stop projection '47 of the spring mounted sliding block 46 projecting into the recess 54, and at the other end by the stop edge 56 for the width of the zig-zag stitch. In this position the stop projection 47 determines the smaller stitch width and the stop edge 56 the greater stitch width.

The size of stitch widths, in a fixed ratio to one another, may therefore be selected as desired by adjusting the control knob 68. In the sewing of buttonholes for example, only the desired narrow stitch width need be adjusted with the control knob 68 in order to have the correct wide stitch after the narrow stitch is completed by turning the adjusting knob 10 counterclockwise as far as the abutment element 61 on the edge 56 will allow and to have the original narrow stitch width effective again by turning back the adjusting knob 10 until it strikes against the stop projection 47.

After making the second narrow stitch and the second wide stitch, the straight stitches can be sewn for sewing up the buttonhole by simply turning the adjusting knob 10 clockwise so that the stop element 61 engages and displaces the stop projection 47 against the pressure of the spring 42 and firmly strikes against the stop edge 55 for the straight stitch. After making the sewing up stitches the limitation for the narrow stitch width is reestablished under the action of the spring 42.

The position of the control knob 68 remains unchanged and thus for every buttonhole of a series, sewing of the identical widths of the narrow stitch and wide stitch is determined merely by operating a single adjusting knob.

The invention is not limited to household machines and the size ratio of the stitch widths can be selected as desired by selection of different stop members such as the limiting member 15.

Returning to the description of operation of the embodiment of FIGS. 2-6 and 10-12, for arresting the tilting movement of the lever 11, the lever 11 has an extension 81 (FIG. 12) that is spring biased, and that has a nose 82 for insertion into notches. such notches may be of the type as indicated at 41 in FIG. 7. I

As described before, the forked lever 6 has an extension 83 at the end opposite relative to the bifurcation, and is connected by a bolt 84 to the tiltable guide or needle bar oscillator 86 that swings about the axis of the pin 85, to impart to the needle bar 87 a swinging motion, for zig-zag stitching. The needle bar 87 is driven from the shaft 2. The stroke of the cam 5 is so arranged that for each completed up and down movement cycle of the needle bar 87, the cam will complete a one-half turn, and will tend to swing the forked lever 6 about the bolt 84. When the adjustable knob 10 is in the zero position, v the eccentric head 8 of the bolt 9 is so positioned that For instance,

the guide slot 88 thereof is tangential relative to the axis of the bolt '84. In this position of the knob 10, the sliding block 7 will slide in the guide slot 88, and the tiltable guide 86 will be at rest, and the forked lever 6 will swing about the axis of the bolt 84.

When the knob 10 is turned away from its zero position, the guide slot 88 will no longer be tangential relative to the axis of the bolt 84, but will form an angle with the tangential direction, and the movement imparted by the cam to the forked lever 6 will result in a longitudinal component of the movement of the forked lever 6, owing to the engagement of the sliding block 7 in the guide slot 88. This longitudinal component will cause an oscillating movement of the needle bar guide 86, and thereby of the needle bar 87.

The cam 5 may be of triangular shape, thus dividing the stroke during each one half turn of the cam 5 into an active component and an inactive component of force imparted to the forked lever 6. The cam 5 may be so positioned that the active component, which imparts motion to the forked lever 6, will be at a time in which the needle bar 87 during its up and down movement will be in the regions of its topmost position.

Tilting of the lever 11 determines, at zero position of the knob 10, the position of the stitch line. The three notches (of the type shown at 41 in FIG. 7) may be engaged by the nose 82 of the extension 81. Insertion in one of the notches will determine whether the position of the stitch line will be to the right, in the center, or to the left. As the nose is positioned in the central notch, the lever 11 will be arrested in a position which, at zero position of the knob 10, determines the stitch line in the center of the stitching hole; upon turning of the knob 10, the zig-zag stitch will extend to both sides of that stitch line. 'If, instead, the nose 82 of lever 11 is in engagement with the right notch, the zero stitch line will be positioned to the right, and the zigzag stitch will extend to the left thereof; conversely, when the nose 82 engages the left notch, the zero stitch line will be positioned on the left, and the zigzag stitch will extend to the right thereof.

Furthermore while the invention has been described in detail with respect to preferred examples of devices for adjusting and limiting the stitch width in zig-zag sewing machines, it will be appreciated by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as set out in the appended claims.

We claim:

1. In a zig-zag sewing machine having a housing supporting a drive shaft, a needle bar oscillator, an oscillator cam geared to said drive shaft in said housing, a guide lever having a bifurcated end in engagement with said cam and an end pivotally linked to said needle bar oscillator, adjustable guide means operable to control the stitch width including a rotatable bolt extending into said housing supporting at one end a guide member defining a guide slot and supporting an adjusting knob at its other end externally of said housing, a sliding block on said guide lever operatively engaging said guide slot, and adjustable stop means operatively associated with said bolt for determining a minimum limit for stitch width while simultaneously determining a maximum limit for stitch width and maintaining a predetermined ratio between minimum and maximum stitch width, said stop means including stop tracks and an abutment element movable by rotation of said bolt into engagement with one of said stop tracks and means movable independently of said bolt to adjust the relative position of said stop tracks and said abutment element.

2. In a zig-zag sewing machine having a housing supporting a drive shaft, a needle bar oscillator, an oscillator cam geared to said drive shaft in said housing, a guide lever having a bifurcated end in engagement with said cam and an end pivotally linked to said needle bar oscillator, adjustable guide means operable to control the stitch width and stitch location including a rotatable bolt mounted in said housing supporting at one end a guide member defining a guide slot and supporting an adjusting knob at its other end externally of said housing, a sliding block on said guide lever operatively engaging said guide slot, a mounting plate disposed on said housing presenting locking notches, and a laterally movable shifting lever pivoted at one end in the housing and having a portion spaced from its pivot supporting said bolt for rotation and for swinging movement about said pivot, and having an arm extending from said housing adapted to engage said notches on said plate for setting the stitch location, and ajustable stop means operatively related to said bolt and adapted to control and limit the rotation of said bolt in at least one direction and thereby the stitch width for determining a minimum limit for stitch width while simultaneously determining a maximum limit for stitch width and maintaining a predetermined ratio between minimum and maximum stitch Width, said stop means comprising a control device including said knob movable to positions corresponding to selected stitch widths, a member presenting a pair of stop conformations arranged at fixed relative positions, an abutment element alternately movable by means of said control device into engagement with one of said stop conformations, and a sliding element yieldingly disposed in the path of said abutment element.

References Cited in the file of this patent UNITED STATES PATENTS 1,830,126 Myers Nov. 3, 1931 2,378,534 Beyer June 19, 1945 2,557,992 Nilles June 26, 1951 2,653,557 Casas-Roberts et al. Sept. 29, 1953 2,713,838 Johnson et al. July 26, 1955 FOREIGN PATENTS 525,454 Belgium Jan. 15, 1954

Images