US3460496A

US3460496A - Zigzag sewing machine with control means for producing buttonholes

Info

Publication number: US3460496A
Application number: US628322A
Authority: US
Inventors: Willi Meier
Original assignee: GM Pfaff AG
Current assignee: GM Pfaff AG
Priority date: 1961-04-05
Filing date: 1967-04-04
Publication date: 1969-08-12
Anticipated expiration: 1986-08-12
Also published as: US3117542A; CH402580A; DE1131494B; CH452331A

Description

Aug. 12, 1969 MEIER 3,460,496

ZIGZAG SEWING MACHINE WITH CONTROL MEANS FOR PRODUCING BUTTONHOLES Filed April 4, 1967 :s sheets-sheet 1 mvrsmorz.

w/Lu MEIER BY mqez. BAT A TTORNEY ZIGZAG SEWING MACHINE WITH CONTROL MEANS Filed April 4 19 7 FOR PRODUCING BUTTONHOLES 3 sheetssheet 2 INVENTOR.

W/LLI MEIER BY mun, .24 m

A TTORNEY Aug. 12, 1969 Filed April 4, 1967 W. MEIER ZIGZAG SEWING MACHINE WITH CONTROL MEANS FOR PRODUCING BUTTONHOLES 5 Sheets-Sheet 5 INVENTOR.

WILL! MEIER MEL @8779 A TTORNE Y United States Patent US. Cl. 112-458 9 Claims ABSTRACT (BF THE DISCLOSURE A zigzag sewing machine including control means to vary the stitching position, the overstitch width, and the stitching direction, is adapted for the semi-automatic sewing of buttonholes of varying length by a control device comprising three control cams mounted upon a common shaft and fitted with cooperating cam followers operably connecting the same with the respective control means of the sewing machine, said cams having coordinated control sections, whereby to enable the sewing, in the order named, of first buttonhole side stitches in one direction, first buttonhole barring stitches and second buttonhole side stitches in the opposite direction, and second buttonhole barring stitches in said first direction, by rotation of said shaft through successive angular ranges in respect to an initial or starting position. The length of the buttonhole stitches sewn is controlled by a ratchet counter having successive toothed sections and actuated by a reciprocating control pawl operated in synchronism with the needle zigzagging oscillations of the machine, the design and relative position of said ratchet sections, in respect to the coordinated cam sections, being such as to result in the automatic sewing of a first row of buttonhole stitches, having a length defined by the angular distance of a first ratchet section, followed by the sewing of first buttonhole barring stitches controlled by a second ratchet section, and initiation of the sewing of the second row of buttonhole side stitches upon said pawl becoming disengaged from said second ratchet section, to interrupt rotation of the ratchet. Upon the row of second side stitches reaching a length equal to the length of first buttonhole stitches, sewing of the second barring stitches is then initiated manually by the operation of a key or the like control member, to rotate the ratchet, by means of an auxiliary pawl, into engagement of said first pawl with a third toothed section thereof spaced from said second toothed section, said third section and the coordinated cam sections causing the sewing of the second barring stitches of the buttonhole. By adjusting the initial position of the first toothed ratchet section in relation to said control pawl by the aid of an adjusting knob carried by said shaft and associated scale and indicating means, the length of the initially automatically sewn buttonhole side stitches may be varied between a maximum, defined by the angular distance of the first ratchet section, and a minimum, it being merely necessary for the operator aside from the initial adjustment of the device for the desired buttonhole length, to ascertain the instant of the second buttonhole side stitches reaching the starting point of the first side stitches and to operate said key for the completion of the buttonhole by the sewing of the final barring stitches thereof.

The present invention relates to a control device for the semi-automatic sewing of buttonholes of varying and preselectable length by means of zigzag sewing machines, involving the sewing, in the order named, of a first row 3,460,496 Patented Aug. 12, 1969 ice of buttonhole zigzag side stitches, first barring stitches, a second row of buttonhole side stitches, and second or final barring stitches, which may be followed by final locking stitches, to firmly anchor the buttonhole in the fabric. The control of the foregoing buttonhole sewing phases, that is, variation of the needle stitching position, of the zigzag amplitude or overstitch width, and of the stitching direction, is customarily effected by means of cams operably connected with the respective control organs of the sewing machine and controlled by the main drive shaft of the machine through suitable overrunning couplings or the like motion-transmitting devices.

Known zigzag sewing machines adapted for the sewing of buttonholes ordinarily enable the sewing of buttonholes of a given size or length only. This deficiency is considered as a great disadvantage and short-coming in practice, in that it is necessary for most applications to vary the buttonhole length, to conform with different sizes of buttons in connection with the different kinds of work at hand.

Solutions to overcome the foregoing disadvantages have been proposed in the past which differ from the known constructions by the use of control cams for the sewing of buttonholes of varying length, said cams being dis connected from or only intermittently operated by the main drive shaft of the sewing machine. Thus, according to one known arrangement, the various buttonhole sewing phases are controlled by the manual and progressive operation of the respective control cams. This manual switching from one to the next buttonhole sewing phase has the disadvantage, among others, of the length of the side and barring stitches of the buttonhole being controlled by the operator, whereby to render the appearance of the buttonhole largely dependent upon the personal factor.

According to another solution proposed heretofore, the drives of the control cams are adjusted manually in that a first actuation results in the successive sewing of first barring stitches followed by first side stitches, and a second actuation results in the subsequent sewing of the second .barring stitches followed by the second side stitches of the buttonhole. Among other drawbacks, this method of buttonhole sewing is disadvantageous in that is makes it impossible to achieve a satisfactory closing of the buttonhole by the first barring stitches, which .should normally overlie the last side stitches, having been sewn at the start of the buttonhole cycle.

Accordingly, among the objects of the present invention is the provision of a control device for zigzag sewing machines for the semi-automatic sewing of buttonholes of varying and preselectable length, which device is substantially devoid of the foregoing and related disadvantages and drawbacks inherent in the prior art arrangements; by which manual operations during a buttonhole sewing cycle are reduced to a minimum; by which the length of the buttonhole to be sewn may be adjusted readily and instantly between a maximum and a minimum with the aid of suitable direct reading scale and indicating means; and which is both simple in construction as well as efiicient and reliable on operation in ensuring the attainment of buttonholes consistently and uniformly and being of plea-sing appearance.

The invention, both as to foregoing and ancillary objects as well as novel aspects thereof, will be better understood from the following detailed description, taken in reference to the accompanying drawings forming part of this specification and in which:

FIG. 1 is a perspective View of a buttonhole sewing control device for zigzag sewing machines, being constructed in accordance with the principles of the invention;

FIG. 2A to 2G are detail views separately and more clearly showing the various control cams and ratchet counters forming part of FIG. 1, the consecutive operating positions of the parts, or buttonhole sewing phases, being indicated by the dot-dash radial lines for ease of illustration and explanation of the function and operation of the invention;

FIG. 3 is a fragmentary perspective view illustrating a modification of FIG. 1; and

FIG. 4 more clearly shows a component part of FIG. 3.

Like reference numerals denote like parts throughout the different views of the drawings.

With the foregoing objects in view, the invention, according to one aspect thereof, involves the provision, in conjunction with a zigzag sewing machine, of a control device for the semi-automatic sewing of buttonholes of adjustable length, said device comprising essentially first, second and third control cams mounted upon a common shaft and having cooperating first, second and third cam followers operably connecting the same with the control means of the sewing machine for the adjustment of the stitching position, the overstitch width, and the stitching direction, respectively. Said cams are provided with successive sections designed to establish predetermined coordinated operating positions of said control means, whereby to enable the consecutive sewing, during rotation of said shaft from a starting position and in the order named, of first buttonhole side stitches in a first direction, of first buttonhole barring stitches and second buttonhole side stitches in the opposite direction, and of second barring stitches in said first direction. The length of the buttonhole stitches is controlled by a ratchet counter mounted upon said shaft and operated by a reciprocating pawl controlled and actuated in synchronism with the needle zigzagging oscillations of the sewing machine, such as by connecting said pawl with the oscillating guide controlling the overstitch width of the machine in a manner well known.

The ratchet counter has a plurality of toothed peripheral sections coordinated with the respective cam sections, in such a manner as to first automatically sew one row of button hole side stitches of predetermined length, defined by the angular distance of a first ratchet section, followed by first barring stitches, defined by a subsequent section of said ratchet counter, and to subsequently initiate the sewing of the second buttonhole stitches upon said pawl becoming disengaged from said second ratchet section, whereby to interrupt rotation of the latter.

There is further provided in accordance with the invention a key or the like control member together with means to manually rotate the ratchet to a position of engagement of said pawl with a third ratchet section for the initiation of the sewing of the second barring stitches of the buttonhole. The maximum length of the buttonhole which can be sewn is determined by the angular distance of said first ratchet section, whereby by pre-setting or initially rotating the ratchet, by rotation of said shaft by the aid of a control knob and associated indicating scale, to a position of said pawl engaging an intermediate point of said first ratchet section, the length of the automatically sewn buttonhole side stitches may be varied between a maximum and a minimum, it being thereafter merely necessary for the operator to watch for the instant of the second buttonhole side stitches reaching a length equal to the length of the first side stitches and to depress said key for the completion of the buttonhole cycle by the sewing of the final barring stitches thereof.

Among the advantages of a device according to the invention, the control cams of which are operated to one or more adjusting positions independently of the drive of the machine, is the fact that only the cam serving for the control of the stitching position has a varying co-ntour of effecting the required control in the foregoing positions, whereby to dispense with the usual manual adjustment of the stitching position prior to and after a button hole sewing cycle. Besides, the control member for the adjustment of the length of the button hole may ad ditionally serve, in the idle position of the cams, for the adjustment of the stitching position during normal operation of the sewing machine.

Referring more particularly to the drawings, FIG. 1, the numeral 1 denotes the needle bar of a conventional zigzag sewing machine carrying a sewing needle and mounted for reciprocation in the vertical direction in a needle bar frame or holder 2, as indicated by the double arrow a, said frame being in turn mounted for oscillation at right angle to the work feeding direction about a fixed pivot or spindle 3 supported by the frame of the machine, as indicated by the double arrow b in the drawing. Reciprocation of the needle is effected in a known manner by coupling of the needle bar l with the main drive or arm shaft 4 of the sewing machine via a crank 5 and link 6 connected to a journal pin 7 affixed to the bar 2. Linked to the needle bar frame 2 is one end of a control bar 8 whose opposite end is in turn linked to the slide block 10 of the control guide 9 of the zigzag drive mechanism of the machine.

The control guide 9 is rotatively supported at its lower end by an arm 11 of a double lever 12 rotatively supported upon a spindle or axis 13 being fast on the frame of the sewing machine. The remaining arm 14 of the lever 12 acts as a cam follower resiliently engaging a cam 16 by the action of a tension spring 15 having one end connected to the arm 11 and having its opposite end connected to the frame of the machine.

A fork-shaped extension 17 of the upper part of the control guide 9 embraces an eccentric l8 rotatively mounted upon the spindle 13. The eccentric 18 is driven by the main drive shaft 4 via a worm 19 fast on said shaft and meshing with a worm gear 20 journalled upon the spindle 13 and affixed to said eccentric, whereby to subject the guide 9 to periodic oscillations about its axis within the arm 11 of the lever 12.

Rotatively mounted upon the end of the link or control bar 8 connected to the slide block 19 is a further link 21 to which is in turn rotatively connected an arm 22 of a double lever 23 rotatively mounted upon a shaft or spindle 24 fast on the frame of the machine, the remaining arm 25 of said lever resiliently engaging a further cam 27 by the action of a spring 26 having one end connected to the joint between lever arm 22 and link 21 and having it opposite arm connected to the frame of the machine, Both the cam 27 and the previously described cam 16 are rigidly mounted upon a control shaft 28 rotatively supported by the frame of the machine, said shaft carrying a pair of

further cams

29 and 30 and a pair of

counter ratchets

31 and 32 and being fitted at its extreme end protruding beyond the housing of the machine with a control knob or disk 33.

Cooperating with the cam 29 is an arm 34 of a further double lever 35, rotatively supported by the frame, whose remaining lever arm 36 engages an abutment or extension 37 of a stitch controller guide 33 of well known construction.

Further mounted upon the main drive shaft 4- of the machine is an eccentric 39 embraced by the forked end of a control lever 40 having an intermediate point thereof rotatively connected to the slide block 41 of the stitch controller movable within the guide 38. Depending upon the angular position of the guide 38, in respect to its rotating axis, the work feed dog (not shown) of the sewing machine, being operably connected to the remaining or lower arm of the lever 40, has imparted to it varying reciprocating feed movements in the forward or reverse sewing direction, respectively, thereby determining the length of the stitches being sewn by the needle in cooperation with a loop taker (not shown), in a manner well known to those skilled in the art.

A tension spring 42, having one end connected to the extension 37 of the guide 33 and having its opposite end connected to the frame of the sewing machine, acts to resiliently urge the lever arm 34 into contact with the cam 29.

Cooperating with the ratchet 31 (see also FIG. 2B), being fitted with peripheral ratchet teeth 45, except for the free or smooth sections 43 and 44, is a main pawl 46 linked to the control guide 9, a torsion spring 47 serving to resiliently urge said pawl into engagement with the ratchet 31.

The ratchet 32 is fitted with ratchet teeth 50 upon two peripheral sections 48 and 49 only, the intervening

peripheral sections

51 and 52 being smooth or free from teeth, as more clearly shown in FIG. 2C. Cooperating with the ratchet 32 is a first auxiliary control pawl 53 being linked to an arm of an oscillating lever 54 rotatively mounted upon the frame of the machine and having its remaining arm actuated by a cylindrical cam 55 fast upon the main drive shaft 4 of the sewing machine and engaging a roller 56 carried by said lever. A torsion spring 57, engaging the pawl 53, on the one hand, and engaging the lever 54, on the other hand, acts to resiliently urge pawl 53 into engagement with the ratchet 32, while a tension spring 58, having one end connected to the lever 54 and having its opposite end connected to the frame of the machine, acts to resiliently urge the roller 56 into engagement with the cam 55.

, Cooperating with the ratchet 32 is a further auxiliary pawl 59 linked to a lever arm 60 and resiliently urged against said ratchet by the action of a torsion spring 61. Arm 60 is connected to a control shaft 62 journalled in the frame of the sewing machine and carrying at its outer extremity, protruding beyond the housing of the machine, a key or the like control member 63. Deflection of the arm 60 is limited by a pair of abutments 64 and 65 fast upon the frame, said arm being normally urged towards the abutment 64 by the action of a spring 66 having one end connected to the arm and having its opposite end connected to the frame of the machine.

Cam 30 serves to actuate a pointer 67 rotatively mounted upon the frame and urged with its camming arm or projection 69 into resilient engagement with the cam 30, for adjustment of said pointer by means of the knob as indicated by the arrow 0. The end of the pointer 67 protrudes beyond the housing of the machine and cooperates with a scale member 7 0 carrying an indicating scale 71 being an identical representation of the range of buttonhole lengths which may be sewn by the machine, say from a minimum to 35 mm, according to the example shown in the drawing. Next to the scale 71, the member 70 carries a pair of further index marks 72 and 73 for the adjustment of the pointer 67 for normal sewing by means of the control knob 33, whereby to cause arm 69 to engage the respective grooves or depressions 74 and 75 of the cam .30.

In FIG. 1, the individual parts of the control device are shown in their position at the start of a buttonhole sewing cycle or operation, to produce a buttonhole of maximum length, that is, 35 mm. according to the example illustrated. FIGS. 2A to 2G separately show the

control cams

16, 27, 29, 30 and

ratchets

31 and 32 with the consecutive control positions of the parts, in rerespect to the coordinated cooperating control or actuating means 14, 25, 34, 69, 46 and 53, indicated by the diametrical lines A to H for ease of illustration and explanation of the function and operation of the invention as described in the following in reference to the drawings.

In the adjusting position of the device between positions A and B, that is, upon rotation of the knob 33 to a desired buttonhole length as indicated by scale 71, the pawl 46 engages an intermediate tooth of the series 45 of the ratchet 31, FIG. 2B, whereby to result in the sewing of a predetermined number of first buttonhole side stitches, in the manner as will become further apparent as the description proceeds.

During the latter operation, the control guide 9 is adjusted to and maintained at a central position by the cam 16 and via the double lever 12, the slide block is displaced, via the double lever 23, to a position within the guide 9 to impart to the needle bar 1 an oscillating amplitude or overstitch width of say 1.6 mm., suitable for the sewing of the side stitches of the buttonhole to be produced, and finally the guide 38 of the stitch controller is displaced, by the cam 29 and via the double lever 35, to a position to maintain a minimum feed stroke or stitching length in the forward sewing direction of the machine according to the example shown and further described in the following. During this operation, the pawl 53 by engaging the smooth section 52 of the ratchet 32 is ineffective.

During operation of the sewing machine, the eccentric 18 is driven by the main drive shaft 4 via the worm gears 19 and 29, whereby to oscillate the control guide 9 about its axis within the arm 11 of the lever 12. The oscillations of the guide 9 are in turn imparted, via the pawl 46 upon the ratchet 31, whereby to advance and rotate the latter in clockwise direction by one tooth during each stitching cycle or zigzag stitch sewn by the machine. Depending upon the shape of the

cams

16, 27 and 29, the individual phases of a buttonhole sewing cycle are controlled in succession, whereby cam 16 determines, via the double lever 12, the position of the guide 9 and in turn the needle stitching position, cam 27 determines, via the double lever 23 and link 21, the posi tion of the slide block 10 within the control guide 9 and in turn the overstitch width or amplitude of the zigzag stitches, and finally cam 29 determines, via the double lever 35, the angular position of the guide 38 of the stitch controller and in turn the feed stroke and work feed direction of the sewing machine, respectively. Between the operating positions A and B, the contours of the

cams

16, 27 and 29 have a constant radius, whereby to effect sewing of the right hand row of buttonhole stitches in the forward direction d, as shown in FIG. 5.

Upon passing beyond the position B, the toothed section 48 of the ratchet 32, FIG. 2C, is engaged by the pawl 53 which now assumes the drive of the shaft 28. Due to the direct operation of pawl 53 by the main drive shaft 4 and its greater operating stroke, shaft 28 is driven by said pawl at six times, according to a practical example, the speed, compared with the speed of pawl 46. As a consequence, the barring stitches 76 of the buttonhole being sewn between the positions B and C of the parts are controlled more precisely stitch by stitch, while at the same time avoiding excessive friction by enabling the provision of a more smooth or gradual transition between the sections of

cams

16, 27 and 29.

During the sewing of the barring stitches 76, FIG. 5, the guide 9 is deflected by the double lever 12 from its Center to its Left position, the slide block 10 is operated by the cam 27 and via the double lever 23 to a position so as to impart to the needle bar 1 an oscillating amplitude or overstitch width of say 3.5 mm., suitable for the sewing of the stitches 76. Besides, the cam 29, FIG. 2F, operates during its rotation from position B to position C, the guide 38 of the stitch controller to a position to cause a reversal of the stitching direction from d to 2, FIG. 5. As a consequence, the first (lower) barring stitches 76 of the buttonhole are sewn automatically upon completion of the first side stitches 75 of predetermined length by means of the knob 33 in the manner described.

In the position C, both

pawls

46 and 53 engage the smooth sections 43 and 51, respectively, of the

ratchets

31 and 32, whereby to prevent the latter from further rotating the shaft or spindle 28. At the same time, the cam 27 causes a displacement of the slide block 10 within the guide 9, to result in the overstitch width being returned to 1.6 mm., according to the example mentioned, for the sewing of the second or left hand side stitches 77, FIG. 5, of the buttonhole. In this position of the parts,

" the

cams

16, 27 and 29 remain idle or inoperative.

7 the first side stitches 75 has been reached, the shaft 28 together with the

cams

16, 27, 29 and 3d and ratchets 31 and 32 is operated manually to the position D of the parts by depressing the key 63. More particularly, depression of the key 63 causes the lever arm 60 to be rotated or deflected to a position of engagement with the abutment 65', whereby to actuate the pawl 59 and in turn to rotate the ratchet 32 until the pawl 53 engages behind the first tooth 59 of section 49, FIG. 2C. After this operation which may be carried out while the sewing machine remains in running condition, pawl 53 again assumes the drive of the

cams

16, 27 and 29, in the manner described hereinbefore, for the sewing of the second (upper) barring stitches 78 of the buttonhole, while at the same time the feed direction is returned to normal or forward sewing by the cam 29.

In the position E of the parts, the pawl 53 becomes disengaged from the toothed section 49 and engages the smooth section 52 of the ratchet 32, whereby the pawl :6 again assumes the further drive of the

cams

16, 27 and 29. In this position, the slide block 10 of the guide 9 is displaced, via cam 27, double lever 23 and link 21, to its lowermost position within said guide, for the sewing of straight stitches (zero overstitch width), to result in a number of locking stitches firmly anchoring the button hole in the fabric.

Upon reaching the position F of the parts, the pawl 46 engages the smooth section 44 of the ratchet 31, thus interrupting the drive of the ratchet and in turn of the shaft 28. Besides, cam acts to rotate the pointer 67 to a point outside the scale or field 71.

In order to start a new buttonhole sewing operation, knob 33 is again rotated in the direction of the arrow 0 until the pointer indicates the desired buttonhole length upon the scale 71, whereupon a new buttonhole cycle may be commenced in the manner described.

In order to utilize the machine for normal sewing, the shaft 28 is adjusted, by the aid of the knob 33, to a position G or H, whereby to cause the pointer to coincide with one of the index marks 73 or 73, respectively. In these positions of the parts, the

cams

27 and 29 remain idle, while cam 16 allows of the adjustment of the stitching position Center or Left, respectively. Grooves 74 and 75 of cam 36, being engaged by the projection 69 of the pointer 67, enable an accurate adjustment or setting of the cam 16 to the positions G and H, while at the same time providing adequate safety against unintentional rotation of the knob 33.

There is thus provided by the invention a semi-automatic control device for a zigzag sewing machine for the sewing of buttonholes of varying length, whereby initial setting or adjustment of the device for a desired buttonhole length will result in the automatic sewing of a first row of buttonhole zigzag side stitches followed by the sewing of first buttonhole barring stitches and the initiation of the sewing of the second row of buttonhole side stitches, whereupon manual operation of a key or the like control member, upon the second row of buttonhole stitches assuming a length equal to said first row of buttonhole stitches, will result in the completion of the buttonhole by the sewing of the second barring stitches thereof. The various buttonhole sewing phases, that is, control of the stitching or zigzag line position, overstitch width and stitching direction, are effected by suitably designed cams operably connected with the respective control organs of the zigzag sewing machine, while the length of the first row of buttonhole stitches and the first barring stitches are controlled by a suitably designed ratchet counter coordinated with said cams and actuated in synchronism with the zigzagging needle oscillations of the machine.

For certain uses, ratchet 32 may be dispensed with, in which case ratchet 31 serves to control the complete buttonhole sewing operation, with the first row of side stitches being sewn between positions A and B, FIG. 2B,

with the first barring stitches being sewn between positions B and C, with the second side stitches being sewn while the ratchet remains at rest between positions C and D, with the second barring stitches being sewn between positions D and E, and with the final locking stitches of the buttonhole being sewn between position E and F, respectively. In this case, the toothed sections of the ratchet 31 B-C and D-E are preferably provided with teeth of a greater pitch, compared with section A-B, to conform with the greater amplitudes of pawl 46 as a result of the increased overstitch width during sewing of the buttonhole barring stitches. On the other hand, the arrangement shown comprising a special ratchet 32, FIG. 26, for the control of the barring stitches, via the cam 55, lever 54, pawl 53, ratchet 32, ratchet 31, pawl 46 and guide 9, has the advantage of a more precise and eificient control and improvement of the appearance of the buttonhole, or reduced distortion of the barring stitches, as pointed out hereinbefore.

Referring to FIG. 3, there is shown an alternative arrangement for the indication of the buttonhole length. According to this embodiment, there is provided, in place of the cam 30 and control knob 33 of the FIG. 1 construction, a ratchet cooperating with a pawl 169, FIG. 4, and an adjusting knob or disk 133, FIG. 3, mounted upon shaft 28.

Knob 133 is provided with two adjusting

marks

172 and 173 and a scale or symbol 171 for the initiation and control of the buttonhole sewing operation. An index 101 upon the frame of the machine serves, in cooperation with knob 133, for the adjustment of the positions of the

control cams

16, 27 and 29.

The symbol 171 is subdivided into an indicating section 171a for the first row of buttonhole stitches and a section 1711) indicating the first barring stitches. Section 171 a the beginning and end of which corresponds with lines A and B of FIG 2, is fitted with indicating numbers, to facilitate its adjustment to a desired buttonhole length. The subidivisions of section 17111 correspond to the lines B to F for buttonhole sewing of FIG. 2, while the two marks 1'72 and 173 correspond to the positions G and H for ordinary sewing, FIG. 2, respectively.

In order to accurately fix the sewing line positions Center and Left, respectively, by the marks 172 and 1'73 cooperating with the index 161, the ratchet 130 is provided with grooves or depressions 174 and 175, FIG. 4, engaged by the pawl 169 by the action of a spring 178.

Adjustment of the buttonhole length in the case of the FIG. 4 modification is effected by the knob 133 prior to the commencement of a buttonhole sewing operation, to cause the mark 101 to coincide with the respective number of the scale 171a.

The operation of the sewing machine fitted with a control device according to FIGS. 3 and 4, both for the sewing of a buttonhole, or for use of the machine during ordinary or straight sewing, is substantially similar to the operation and control of the device according to FIGS. 1 and 2.

It is understood that the buttonhole sewn in the manner is subsequently cut, either manually or automatically, along a line intermediate the side stitches 60 and 62, FIG. 3, by the aid of a suitable buttonhole cutter, in a manner well known to those skilled in the art.

In the foregoing the invention has been described in reference to an exemplary and illustrative device. It will be evident, however, that variations and modifications, as well as the substitution of equivalent parts or elements for those shown and described herein 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 drawings are accordingly to be regarded in an illustrative rather than in a restrictive sense.

I claim:

1. In a zigzag sewing machine including first control means to vary the needle stitching position, second control means to vary the overstitch width, and third control means to vary the stitching direction, means for controlling the sewing of buttonholes comprising in combination:

(1) first, second and third control cam means mounted upon a common shaft,

(2) cooperating first, second and third cam follower means operably connecting said cam means with said first, second and third control means, respectively,

(3) said cam means having control sections designed to establish predetermined coordinated operating positions of said control means such as to efiect the sewing, in the order named and during rotation of said shaft from a starting position through consecutive operating positions of said control sections engaging the associated cam follower means, of first buttonhole side stitches in a first direction, of first buttonhole barring stitches and second buttonhole side stitches in the opposite direction, and of second buttonhole barring stitches in said first direction,

(4) ratchet counter means mounted upon said shaft and reciprocating control pawl means therefor with means to actuate said control pawl means in synchronism with the needle zigzagging oscillations of said machine,

(5) said ratchet means having a plurality of toothed sections coordinated with said cam sections, whereby to automatically sew a first row of buttonhole side stitches of predetermined length defined by the angular distance of a first toothed section and followed by first buttonhole barring stitches defined by a second toothed section of said ratchet means, and to subsequently automatically initiate the sewing of the second row of buttonhole side stitches upon said pawl means becoming disengaged from said second toothed section, to interrupt rotation of said shaft, and

(6) manually actu-atable control means to rotate said ratchet means to a position of engagement of said pawl means with a third toothed section thereof spaced from said second section, to eifect sewing of the second barring stitches of the buttonhole.

2. In a buttonhole zigzag sewing machine as claimed in claim 1, including manual control means to rotate said shaft and scale and index means operably connected therewith, to vary the initial relative adjusting position between said first toothed section of said ratchet means and said pawl means.

3. In a buttonhole zigzag sewing machine as claimed in claim 2, said cam and ratchet means provided with auxiliary sections, exterior of said first-mentioned sections serving for buttonhole sewing, and coordinated indicating means therefor, to adjust the machine for straight stitching at predetermined needle stitching positions.

4. In a buttonhole zigzag sewing machine as claimed in claim 1, said ratchet means being comprised of a first and second ratchet disk mounted upon said shaft and first and second control pawls therefor, said ratchet disks having coordinated toothed sections and said control pawls being arranged such as to cause the first ratchet disk to be effective in sewing the buttonhole side stitches and to cause the second ratchet disk to be effective in sewing the buttonhole barring stitches, and means to drive said second ratchet disk by the sewing machine at an increased reciprocating speed in synchronism with the needle zigzagging oscillations compared with the reciprocating speed of said first ratchet disk.

5. In a buttonhole zigzag sewing machine as claimed in claim 4, including an oscillating member driven by the main drive shaft of said machine, to provide driving force for effecting needle zigzagging movements, first coupling means between said member and said first control pawl, and second coupling means between said drive shaft and said second control pawl including an eccentric upon said shaft and lever means operably connecting the same with said pawl.

6. In a zigzag sewing machine, buttonhole sewing control means comprising in combination:

(1) first, second and third control cams mounted upon a common shaft and operably connected with said machine, to vary the stitching position, the overstitch width and the stitching direction, respectively, in accordance with predetermined angular operating positions of said shaft,

(2) first and second ratchet counter disks also mounted upon said shaft and first and second control pawls therefor, respectively, with means to actuate the same in synchronism with the needle zigzagging oscillations of said machine,

(3) said cams and ratchet disks having coordinated cam and toothed sections, respectively, whereby to consecutively sew, starting with an initial position of said shaft, a first row of buttonholes side stitches of predetermined length defined by the angular distance of a first toothed section of said first disk followed by first buttonhole barring stitches defined by a first toother section of said second disk, and to subsequently automatically initiate the sewing of the second row of buttonhole side stitches upon said pawls becoming disengaged from said disks, to interrupt rotation of said shaft, and

(4) manually actuatable control means to rotate said second disk to a position of engagement of a second toothed section thereof by said second control pawl, to effect sewing of the second barring stitches of the buttonhole.

7. In a buttonhole zigzag sewing machine as claimed in claim 6, said last control means comprising an auxiliary pawl normally disengaged from and intermittently operable into engagement with said second ratchet disk, and a control key and operating lever means therefor connecting the same with said auxiliary pawl.

8. In a buttonhole zigzag sewing machine as claimed in claim 6, including means to cause the drive of said second ratchet disk (in synchronism with the needle zigzagging oscillations) to be at an increased oscillating speed compared with the oscillating speed of said first ratchet disk.

9. In a buttonhole zigzag sewing machine a claimed in claim 7, including an oscillating member driven by the main drive shaft of said machine, to provide driving force for effecting needle zigzagging movements, first coupling means between said member and said first control pawl, and second coupling means between said drive shaft and said second control pawl including an eccentric upon said shaft and lever means operably connecting the same with said pawl.

References Cited UNITED STATES PATENTS 3,130,697 4/1964 Meier 112-158 3,148,645 9/1964 Aiki et al. 112--158 3,149,591 9/1964 Aiki et al. 112158 RICHARD J. SCANLAN, Primary Examiner U.S. Cl. X.R.