US3541981A

US3541981A - Multiple stitch pattern producing mechanism

Info

Publication number: US3541981A
Application number: US744493A
Authority: US
Inventors: William Alexander Watson
Original assignee: Singer Co
Current assignee: SSMC Inc
Priority date: 1968-05-21
Filing date: 1968-07-12
Publication date: 1970-11-24
Anticipated expiration: 1987-11-24
Also published as: GB1181606A

Description

United States Patent Primary ExaminerRichard J. Scanlan, Jr.

[72] lnventor William Alexander Watson Duntocher, Scotland, United Kingdom Attorneys- Marshall 1. Breen, Chester A. Williams, Jr. and F. [21] App1.No. 744,493 Donald an [22] Filed July 12,1968 [45] Patented Nov. 24, 1970 [73] Asslgnee The singer (:ompany ABSTRACT: A mechanism for a sewing machine comprising New York, New York a conventional zigzag cam having superimposed upon it 111 a corporation of New Jersey spaced relation a substantially similar upper zigzag cam modified so that a predetermined number of spaced cam lobes [54] MULTiPLE STITCH PATTERN PRODUCING are removed from thelatter cam. Superimposed upon the con- MECHANISM I ventional zigzag cam in face-to-face relation 18 a second or m- C im 9 Drawing Figs termediate zigzag cam which is similar in design to the aforementioned modified zigzag cam and is operatively associated [52] U.S .Cl. 112/158, with h fi or upper difi d cam and the conventional 74/568 cam, so that indexing of the upper modified cam will effect Int-Cl Dosh 3/02 movement of the second modified cam through a redeter- P [50] Field of Search 1 12/158, i d b r of degrees, whereby the void between the cam 73, 11 1; 74/568 lobes on the conventional zigzag cam will be more fully filled 56 R f d when the cams are so indexed to preferably, a blindstitch posi- 1 e erences I e tion. Adjustment of the cams relative to each other is effected UNITED STATES PATENTS by having a portion of the periphery of a disk to which the 1,524,461 1/1925 Speer 74/568 upper modified cam is attached project through an opening in 2,594,911 4/1952 Goff 74/568 the bracket arm cover arranged to be shifted by the finger of 2,800,808 7/1957 Cappelle et a1. 74/568X the operator. Detent means operatively associated with the 2,999,471 9/1961 Bennink et al 112/158 disk is provided for locking the superimposed cams in their 3,039,323 6/1962 Mori 74/568 selected relative position.

a V l I I I 26' -4 80 iew-= lu n 5 M 1 42 1 B g 31 a... 23 2| Patented Nov. 24, 1970 3,541,981

JNVENTOR. 2 William A. Watson I ATTORNEY Patented Nov. 24, 1970 3,541,981

STITCH WIDTH NEEDLE POSITION INVENTOR.

William A.Wafson MULTIPLE STITCH PATTERN'PRODUCING MECHANISM BACKGROUND OF THE INVENTION 1. Field of the Invention This invention pertains to a mechanism for manually changing the relative phase relationship of the cams in a sewing machine of the zigzag type in order to produce different selected stitch patterns of high quality and for accomplishing the same in a relatively simple and quiet manner.

2. Description of the Prior Art It is generally known in the art to provide in a sewing machine means for changing the stitch pattern. An unsatisfactory arrangement which heretofore has been used to achieve this end comprises a removable cam designed so that it can be mounted on a driven camshaft in one of two positions which are substantially 180 apart. In order to produce a stitch pattern different from the one previously formed the operator of the machine is required to remove the replaceable cam, turn it through 180 and replace the cam in its latter turned position on the camshaft. This type of arrangement requires a substantial amount of effort on the part of the operator and also requires a rather complicated mechanism compared to that required in the use of the present improvement. Other arrangements for altering the stitch pattern are relatively inconvenient to operate and are not as readily accessible to the operator of the sewing machine as is the present invention. In addition, certain of the previously developed mechanisms are notorious for having a relatively noisy mode of operation, which is undesirable to the operator of the machine and those nearby.

SUMMARY This invention relates to the art of sewing machines preferably of the zigzag type, and more particularly to a novel and improved cam mechanism comprising a plurality of relatively phase shiftable cams whereby one of a plurality of predetermined stitch patterns may be selected manually by modifying the angular relationship of the cams in a simple and efficient manner to transmit to the needle carrying needle bar by way of a cam follower and transmission means, a needlejogging motion in conformance with the selected pattern sensed by the cam follower. Further, the cams are so arranged relatively to each other that the cam follower will sense the stitch pattern therefrom with a minimum amount of noise.

The present invention overcomes the above discussed prior art deficiencies and more, by providing a mechanism for selecting a predetermined stitch pattern comprising three coaxially mounted cams adapted to be attached on a rotatable shaft journaled in the frame of the sewing machine wherein one cam is by way of illustration of the conventional zigzag variety and has superimposed upon it in spaced relation, for example, a first or upper similar zigzag cam modified so that every third cam lobe is removed. Superimposed upon the regular zigzag cam in contiguous or face-to-face relation therewith a second or intermediate cam, illustrated as being of the zigzag variety, which is similar in design to the upper modified zigzag cam and slidably carries on its upper surface adjacent the upper modified cam, an actuating plate having a downwardly extending pin registering with a camming slot provided in the intermediate cam. A downward projecting stud carried by the upper modified cam registers with an open ended aperture formed in the actuating plate so that indexing of the cam will effect movement of the plate, which, in turn causes a corresponding movement of the intermediate modified cam through a predetermined number of degrees. Manual adjustment of one cam relative to the other is effected by having a portion of the periphery of the disk to which the upper modified cam is attached preferably projecting through an opening in the bracket arm cover in position to be shifted by the finger of the operator for altering the combined stitch pattern response of the cams to produce one of two or more stitch patterns. It is to be understood that the foregoing cams are not limited to the zigzag variety and do not necessarily have to produce a zigzag stitch pattern in any one of their selected relative positions. It is intended to be-within the scope of the present invention to provide a plurality of cams of different stitch-pattern response-producing surfaces which when indexed produce a predetermined integrated response the pattern of which is determined by the relative orientation of the stitch-pattern response-producing cam surfaces. In the preferred embodiment this end is accomplished by virtue of the cam design and their shiftable mounting arrangementso that in one position the cam lobes of the plurality of cams are in substantial vertical register and a regular zigzag seam is produced, and when the upper modified cam is indexed by means of the finger actuatable disk the lobes on it move through a predetermined number of degrees relative to their previous zigzag position and the intermediate cam is moved by means of the pin in the actuating plate so that its lobes are moved a predetermined fraction of said number of degrees relative to their previous position. Thus, the cam follower is allowed to drop to the low point on the lowermost zigzag cam only once every six needle penetrations, thereby resulting in the production of a blindstitch seam. These seams are merely illustrative of the stitch patterns which may be produced by such a cam mechanism. When intelligence is added to the lower standard zigzag cam as discussed above, the portion of the stitching cycle during which the follower senses the high point of the combined cam response functions in an extremely quiet mode of operation since the orientation of the cam lobes of the modified cams relative to those of the zigzag cam provide a substantially continuous response surface. Thus, there is provided by the present invention a novel and improved construction for a cam indexing mechanism which avoids de ficiencies of the previously designed devices.

Accordingly, it is a primary object of the present invention to provide for use in a sewing machine of the ornamental stitch variety, a novel and improved cam mechanism which is easily adjusted and is readily accessible to the operator of the machine, and which when adjusted will permit the operator to select one or more different stitch patterns.

Another object of the present invention is to provide in a zigzag sewing machine, a manually-actuatable relatively noiseless mechanism for altering the angular relation of the cams to produce a desired predetermined stitch pattern.

It is a further object of this invention to provide for use in a sewing machine of the ornamental stitch variety, a relatively quiet operating mechanism for changing the stitch pattern normally produced by arranging the mechanism so that it is readily accessible to the finger of the operator and need not be completely removed to alter the stitch pattern.

A further object of the present invention is to provide for use in a sewing machine of the ornamental stitch variety, a plurality of cams of different stitch-pattern response-producing shape adapted for relative angular movement and for being locked in a selected relative position.

Having in mind the above and other objects that will be evident from an understanding of this disclosure, the invention comprises the devices, combinations and arrangements of parts as illustrated in the presently preferred embodiment of the invention which is hereinafter set forth in such detail as to enable those skilled in the art readily to understand the functions, operation, construction and advantages of it when read in conjunction with the accompanying drawings in which:

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of the cam indexing mechanism and its related components constructed in accordance with the present invention oriented to produce a first stitch pattern;

FIGS. 2 (a); (b), and (c) comprise a step-by-step assembly showing the relative position of the parts comprising the cam mechanism of the present invention for ultimately producing a first stitch pattern;

machine bracket arm and cover constructed in accordance with the present invention;

FIG. 5 is a vertical sectional view taken substantially on the line 5-5 of FIG. 4;

FIG. 6 is a vertical sectional view taken substantially on the line 66 of FIG. 5;

FIG. 7 is an exploded perspective view of the cam indexing mechanism embodying the present invention.

FIG. 8 illustrates a zigzag stitch pattern produced by the needle with the cams oriented as shown in FIG. 2;

FIG. 9 illustrates a blindstitch pattern produced by the needle with the cams oriented as shown in FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENTS- Referring now to the accompanying drawings wherein like reference numerals designate similar parts throughout the various views, the preferred embodiment of the present invention is herein disclosed as embodied in a sewing machine substantially similar to that forming the subject matter of U.S. Pat. NO. 3,051,107, granted Aug. 28, 1962 to Ralph B. Johnson and assigned to the assignee of the present application, to which reference may be had for a more complete understanding of the machine. The present application describes the parts of the sewing machine only to the extent necessary for a complete and thorough understanding of the present invention.

The sewing machine includes the usual bed (not shown), a standard 10 risingfrom one end of the bed and carrying a bracket arm 11 that terminates in a head (not shown) overhanging the bed. The top of the bracket arm 11 is open and normally is closed by a top cover plate 12. Rotatably journaled in suitable bearings provided in the bracket arm 11 is a horizontally disposedmain shaft 13 extending length wise of the bracket arm and carrying at one end a suitable drive mechanism (not shown). At its opposite end, the main shaft 13 carries a counterbalanced crank 14 connected in the usual manner to a vertically disposed needle bar 15.

In the head of the machine there is mounted for endwise reciprocation and sidewise movement the needle bar 15 having a needle 16 secured to its lower end by a standard needle clamp 17. Upon actuation of the needle bar 15 the needle penetrates the work W (see FIGS. 8 and 9) disposed below it on the work surface of the sewing machine and cooperates in the usual manner with asuitable. stitch forming mechanism (not shown) located below the head in the bed of the machine to form an ornamental stitch pattern, preferably a zigzag stitch (FIG. 8) or a blindstitch pattern (FIG. 9). As readily can be seen from the blindstitch pattern of FIG. 9 the needle 16 is maintained laterally fixed by a needle jogging mechanism including the needle bar 15 at the line of feed of the work W for a predetermined number, preferably four, of straight stitches (5,. S S S and then is moved laterally of the line of feed to produce a predetermined number, preferably two, of zigzag stitches -.Z,, A In the preferred embodiment, as shown in FIG. 9 two zigzag stitches are formed after every four straight stitches. Upon selection of the zigzag stitch pattern shown in FIG. 8, the needle for 15 is vibrated laterally for a predetermined stitching cycle thereby causing-the needle 16 to move laterally of the line of feed of the work W so that upon alternate stitches it will penetrate the work at laterally spaced points to define an ornamental stitch pattern, such as the zigzag seam shown in FIG. 8..

To accomplish the above described stitch patterns the needle bar 15 is mounted for endwise reciprocation in a pair of vertically spaced bearing

lugs

18 and 19 of a swinging needle bar gate 20. To provide for lateral vibration of the needle bar 15, the gate 20 also includes a pair of vertically spaced upper and

lower bearing lugs

21 and 22, respectively. formed with bores (not-shown) for receiving a central portion of a pivot rod 23 which mounts the gate 20 for pivotal movement about the axis of the central portion of the rod 23. For purposes of the present invention it is sufficient to say that the head of the sewing machine mounts the pivot rod 23 in a pair of vertically spaced bosses, referencebeing had to the above identified patent for a more complete description.-

Pivotal movement of the needle bar gate 20 about the axis of the central portion of the rod 23 is imparted there to by means of a pitman 24 adjustably connected at its needle bar end to an L-shaped bracket 25 by means of a hexagonal type screw 26 extending through the bracket and threaded into the pitman. The bracket 25 is pivotally connected to the needle bar gate 20 by a pin 27 secured to the gate by a setscrew (not shown) or other suitable means. The other end of the pitman 24 extends through a horizontally orientated open ended slot 28 formed in a plate 29 that is pivotally mounted on a stud pin 30. The pin 30 is carried in a substantially U-shaped bracket 31 pivotally supported on a stud 32 secured in the frame ofthe bracket arm of the sewing machine. As best shown in FIG. 1, on the side of the plate 29 furthest from the needle bar 15, there is mounted on the end of the pitman 24 an upstanding circular shaped portion 33 disposed in abutting relation to the adjoining surface of the plate 29. The end of the pitman 24 adjacent the plate 29 is adapted to be slidably shifted along the horizontal slot 28 to vary the zigzag amplitude or stitch width at the needle by means of a manually shiftable lever having at one end thereof an upstanding pin 35 secured to a spring member 34 maintained in slidable register with an open ended U-shaped slot 36 provided in an offset shelf member 37 secured to the pitman 24 in a suitable manner, and at its other end'a handle 38, also carried by the member 34, which is readily accessible to the operator of the machine. To vary the field or centerline of the zigzag pattern there is provided a handle 39 carried by a plate 40 which is secured to the bracket 31, whereby the bracket pivotally may be shifted about the stud 32.

Theplate 29 is oscillated by a rotary pattern cam arrangement comprising a

plurality ofcam disks

41,42 and 43 having corresponding peripheral pattern surfaces 44, 45 and 46. The

cams

41, 42 and 43 operably coact with other related parts, to be described in detail hereinafter, to form a cam indexing mechanism generally designated 47 for oscillating the plate 29 in a predetermined selected manner, which, in turn, operably causes the needle 16 to produce preferably either a zigzag stitch or a blindstitch pattern. The

cams

41, 42 and 43 releasably are secured by a shouldered thumb screw 48 threaded in a bore 49 formed in a disk adapter 50, which is journaled on a cam shaft 51 supported by the member 34. The disk adapter has integrally formed therewith a gear wheel 52 which meshes with a worm gear 53 disposed on the main shaft 13. A single cam follower generally designated 54 a laterally extended shelf portion 55 formed with the plate 29 and has a cam follower element 56 for tracking the

peripheral surfaces

44, 45 and 46 of the

cam disks

41,42 and 43. Thus, as the cam follower element 56 senses the combined stitch-pattern response of the cam surfaces 44, 45 and 46 it conveys the tracked pattern to the plate 29, thus causing it to move in conformance therewith and resulting in a corresponding movement ofthe pitman 24, which vibrates the needle 16 carried by the needle bar 15 to produce the selected stitch pattern.

A torsion spring 57 coiled about the intermediate portion of the pivot rod 23 between the bearing lugs 21 and 22 is constructed and arranged to bias the needle bar gate 20 in a co unterclockwise direction thereby tending to pull the pitman 24 to the left which urges the periphery ofthe upstanding portion 33 against the adjacent surface of the plate 29 causing the plate to pivot about the pin 30 in a clockwise direction. Thus, since the cam follower element 56 is mounted on the plate 29 by way of the shelf 55 it also will tend to move clockwise and will be resiliently maintained in tracking engagement with the cam surfaces 44, 45 and 46. As the cam surfaces present a high point to the cam follower element 56, it will tend to move in a'counterclockwise direction imparting a corresponding clockwise motion to the needle bar gate 20 against the action of the normal bias of the spring 57. When the follower element 56 contacts a low point on the cam surfaces the needle bar gate is pivoted in a counterclockwise direction by the spring 57.

To provide the operator with a but, as of stitch patterns the cams are designed so that in one position a blindstitch will result, while in anotherselectedposition a conventional zigzag stitch pattern will be produced. As best shown in FIG. 7, the cam 41 is of a conventional zigzag design with equally spaced cam lobes 58 forming the high points and the low pointsv defined by the surfaces 59 therebetween. The cam 41 may be of any desired design, but as shown in the drawing, is preferably of the eighteen stitch variety. The zigzag cam 41 is formed with a keyhole shaped aperture generally designated 60 comprising an enlarged circular portion 61 for mounting the cam on the adapter 50 and a relatively narrow elongated opening or slot 62 depending therefrom. The adjacent or intermediate cam 42 is illustrated as having six cam lobes 63 and is similar to the zigzag cam 41 except that it is modified so that every third cam lobe is removed. The modified cam 42 is mounted in contiguous relation with the zigzag cam on the cam shaft 51 so that it can be manually shifted angularly about the axis of the cam shaft to change its phase relation with respect to the standard zigzag cam 41. The intermediate cam 42 slidably carries on its upper surface adjacent the upper cam 43, an actuating plate-64 having a downwardly extending pin 65 registering with a camming slot 66 formed in the intermediate cam 42. The intermediate cam 42 coaxially mounts with the cam 41 by means of an opening 67 comprising a cenoverlapping

circular portions

71 and 72 for slidably mounting the plate 64 on the adapter 50 with the pin 65 in register with the slot 66 of the cam 42, as best shown in FIG. 6. The upper cam 43 is of a design similar to that of the intermediate cam 42 including six cam lobes or high points denoted by the reference numeral 73 with low'points comprising the surfaces 74 disposed between the cam lobes. The cam 43 also is provided with an opening 75 for coaxially mounting the cam 43 on the adapter 50 with the

cams

41 and 42 and the actuating plate 64. This latter opening is similar in shape to the opening 67 formed in the intermediate cam 42. There is provided stud 76 depending downward from the cam disk 43 for register with an open ended aperture 77 formed on the periphery of the actuating plate 64. The stud 76 is arranged relative to the earns 42 and 43 so that'indexing of the cam 43 through a certain number of degrees will effect sliding movement of the actuating plate 64 from portion 71 to 72 or vice versa, which in turn causes a corresponding movement of the intermediate cam 42 through a predetermined fraction of the degrees through which the cam 43 has moved.

As shown in FIG. 2, in one position the

cam lobes

63 and 73 of the modified

cam

42 and 43, respectively, are alined in vertical register with the lobes 58 of the regular zigzag cam 41 and a regular zigzag seam such as the one shown in FIG. 8 is produced. The illustrations a, b and c of FIG. 2 show the phase previous zigzag position shown in FIG. 2a, or in other words the cam lobes of the cam 42 only move through substantially one-half of the angular distance moved by the cam lobes 73 of the upper cam 43. This movement is determined by designing the actuating plate 64 so that it shifts a limited amount only that is sufficient to locate the cam lobes of the cams in the position illustrated in FIG. 3c Thus, by virtue of the above arrangement the cam follower element 56 is allowed to contact the low points or surfaces 59 on the zigzag cam 41 only once every six needle penetrations, thereby resulting in the production ofa blindstitch pattern such as illustrated in FIG. 9.

With the cam lobes disposed as shown in FIG. 3, that is, for blindstitch operation, the outer surfaces of the

adjacent lobes

58, 63 and 73 provide a substantially continuous peripheral surface-denoted by the reference numeral 78 for the cam follower element 56 to track during formation of the straight stitches comprising the blindstitch pattern. A constant problem which accomplishes the foregoing mechanism is that any spacing or voids that normally may exist between the adjacent cam lobes comprising the straight stitch portion of the stitching cycle will cause a substantial amount of undesirable noise and also, naturally will affect the quality of the resulting blindstitch pattern. In the preferred embodiment of the present invention any spacing that heretofore has existed between adjacent cam lobes is minimized so that as the follower leaves the peripheral surface of, for example, a lobe 58, it immediately contacts the peripheral surface of the next lobe 63 and that of the lobe 73 in seriatim and so on. This results in a relatively quiet mode of operation and a blindstitch pattern of the desired quality. It readily can be seen from FIG. 3a and 30 that by the above described operation the

cam lobes

63 and 73 of the modified

cams

42 and 43, respectively, are indexed to a position between the lobes 58 of the zigzag cam 41 to fill any void therebetween.

The modified cam 43 preferably is integrally formed with a manually operable actuating dial or disk 79 having a knurled peripheral surface 80. A portion of the periphery 80 ofthe dial 79 is adapted to project through a slot 81 provided in the cover plate 12 for the bracket arm Hand is positioned, as best shown in FIG. 4, to be readily. accessible to the finger of the operator. The dial 79 mounts on the disk adapter in rotary fashion so that the modifiedcam 43 is superimposed upon the regular zigzag cam 41 in spaced relation and the intermediate cam 42 is superimposed upon the cam 41 in face-to-face relation as shown in FIGS. land 5. The opening 75 comprising a circular portion and a fan-tail portion depending therefrom formed in the integrally formed dial 79 and cam 43 allows the cam to be mounted coaxially with the zigzag cam 41 and the cam 42, and to be shifted relative thereto as described above.

In order to lock the three superimposed cams and the plate 64 in a selected relative position there is provided an apertured detent spring generally designated 82 including a slightly relation between each of the elements comprising the mechanism.

When the upper modified cam 43 is indexed in amanner to be described below, the lobes 73 on the cam are moved through an angular distance of substantially 26 (see FIG. 30 relative to their previous zigzag position of vertical alinement (see FIG. 20). Movement of the cam 43 causes the stud 76 depending therefrom to slidably shift the actuating plate 64 from its zigzag position shown in FIG. 2b to its blindstitch position shown in FIG. 3b Thus, by means of the actuating plate pin operatively coacting with the slot 66 formed in the modified cam 42, the latter cam is shifted so that its lobes 63 are moved approximately 13 16 (see FIG. 3a) relative to their downward biased integral finger 83 extending radially thereof and having a detent 84 formed on the lower surface thereof at its free extremity. The aperture in the spring 82 is similar to that formed in the zigzag cam 41 and comprises a circular portion 85 and an elongated opening 86 formed in the finger 83. The spring 82 is mounted adjacent the upper surface of the dial 79 in coaxial relation with the

cam disks

41, 42 and 43, and the actuating plate 64. These elements together with the spring 82 are vertically alined in their proper relative position I by means of a pin 87 depending upward from a curved member 88, which is held in place in a cutout portion (not shown) provided at the top of the gear wheel 52. The member 88 is mounted with the cam shaft 51 by means of a screw 89 (see FIG. 5) and is designed so that it is substantially complementary to the portion removed from the top surface of the wheel 52. The alining pin 87 extends sequentially upward through a bore 90 formed in the disk adapter 50. the slot 62 of the cam 41, the fantail shaped opening 69 of the cam 42, a radially located hole 91 formed in the actuating plate 64, the fantail shaped portion of the opening 75 of the cam 43, and finally through the slotted portion 86 of the spring finger 83.

A pair of circumferentially spaced

depressions

92 and 93 are formed on the upper surface of the dial 79 for receiving the detent 84 of the spring finger 83 and releasably holding the cams and the plate in their selected relative position. The depressions are spaced inward from the periphery of the disk 79 so that their radial location is substantially equal to the radial disposition of the detent 84 relative to the axis of the cam shaft 51. Each of the depressions is substantially radially alined with a

side wall

94 and 95 defining the fantail shaped portion of the opening 75 in the cam disk 43, so that as the disk 43 is shifted angularly relative to the pin between the

side walls

94 and 95, the detent 84 will register with one of the

depressions

92 and 93.

The operator manually may select either a blindstitch or a zigzag stitch pattern by shifting the projecting peripheral portion of the dial 79 either to the right or to the left as shown by the indicia on the bracket arm cover plate 12 in FIG. 4. Thus, when the dial 79 is shifted to the right for a blindstitch pattern.

' the modified cam 43 secured to the dial 79 is indexed so that the phase relation illustrated in FlG. 3 results with the detent 84 in register with the depression 93. The detent carrying finger 83 of the spring 82 is biased downwardly to maintain the detent 84 in contact with the adjacent surface of the dial 79, but is sufficiently resilient to allow the detent to be shifted from one depression to the other. If a zigzag stitch pattern is desired the operator merely shifts the dial to the left as indicated in FIG. 4 whereupon the earns 41, 42 and 43 will be alined as shown in FIG. 2 with the detent 84 in register with the depression 92. This latter arrangement is shown in FIG. 1. Thus, it is seen that the

radial walls

94 and 95 of the fantail shaped opening in the dial 79 form stop abutments for the pin 87 thereby defining the limits of angular shift of the upper cam 43.

The foregoing describes a preferred embodiment of the present invention. However, an alternative for the means by which the earns 42 and 43 are operatively associated for relative angular movement, comprises eliminating the actuating plate 64 and in its place providing a radial slot in the intermediate cam 42 for receiving the pin 76 depending from the upper cam 43, so that the pin then will move the intermediate cam substantially one half the angular distance through which the upper cam moves when it is indexed. This arrangement also would eliminate the need for the camming slot 66 in the cam 42.

Numerous other alterations of the structure herein disclosed will suggest themselves to those skilled in the art. However, it is to be understood that the present disclosure relates to a preferred embodiment of my invention which is for purposes of illustration only and not to be construed as a limitation of the invention. All such modifications which do not depart from the spirit of the invention are intended to be included within the scope ofthe appended claims.

lclaim:

1. In a sewing machine having a frame including a bracket arm, a needle carrying needle bar mounted in said frame for endwise reciprocation and sidewise' movement, a cam stack comprising a first, asecond and a third stitch-pattern cam, at least two of said cams having a different response producing shape, a shaft journaled in said frame for rotation about a single axis, means for mounting each of said cam in superposed relationship on said shaft for rotation therewith, means for rotating said shaft in synchronism with said needle reciprocating movements, a single cam-tracking means carried by said frame for tracking and responding to said cams during a predetermined stitching cycle, means operatively connecting said cam-tracking means to said needle bar for jogging said needle sidewise in conformance with the combined response ofsaid cams sensed by said cam-tracking means, said first and second cams each having an indexing axis about which said first and second cams may be indexed angularly relative to said shaft, said indexing axes being substantially coincident with said single axis, shift means for changing the relative phase relation of said cams, said shift means including means for indexing said first cam from a first position through a first angle about said indexing axes to a second position and concurrently indexing said second cam from a first position through a second angle different from said first angle about said axes to a second position, whereby in said first position of each of said first and second cams the cam stack is so arranged as to produce a seam of one predetermined stitch pattern and when in said second position of each of said first and second cams said cam stack is arranged to produce a seam of a dif ferent predetermined stitch pattern.

2. A sewing machine in accordance with claim 1 wherein said shift means further includes a manually engageable member operatively associated with one of said cams, and being constructed and arranged so that an operator ofthe sew ing machine'will have direct access thereto for shifting said cams to produce the desired stitch pattern.

3. A sewing machine in accordance with claim 2 including a cover for said bracket arm. said cover having at least one aperture formed therein for receiving at least a portion of said manually operative member to facilitate access thereto by the operator ofsaid sewing machine.

- 4. in a sewing machine in accordance with claim I wherein I the response producing surface of said third cam comprises a first number of lobes ofprescribed configuration, the response producing surface of each of said first and second cams comprises a second number of lobes of substantially the same configuration as the lobes of said third cam, said second number of lobes being less than said first number of lobes, each said first position of said first and second cam being such that the lobes of said first cam substantially are alined with the lobes of said second cam and further are alined substantially with certain of said lobes ofsaid third cam for producing a first stitch pattern, and each said second position of said first and second cam being such that the lobes of said cams are offset from each other about the periphery of said third cam for producing a second stitch pattern.

5. A sewing machine in accordance with claim 4 wherein said first cam is superimposed upon said third cam in spaced relation and said second cam is disposed intermediate said first and third cams.

6. A sewing machine in accordance with claim 2 wherein said manually engageably member comprises a disk attached to one of said cams, and being arranged so that a portion of the periphery of said disk projects through said frame and is adapted to be shifted by the finger of the operator.

7. A sewing machine in accordance with claim 2 wherein said cams and said manually engageable member commonly are mounted on said shaft, and including means for locking said cams in a selected relative position comprising a detent for releasably engaging one of a plurality of depressions formed on said manually engageable member.

8. A sewing machine in accordance with claim 7 wherein each of said cams is provided with an aperture predetermined size and shape, said manually engageable member being operably associated with said first cam and being provided with an aperture similar to that provided in said first cam, said locking means comprising a ring member having an integral portion extending therefrom and having a detent formed at its free extremity, said integral portion being provided with an aperture similar to that provided on said third cam, said cam mounting shaft having a pin depending therefrom for register with all of said apertures, said aperture ofsaid third cam being so constructed as to prevent circumferential movement of said third cam relative to said pin, said aperture of said manually engageable member and ofsaid first cam being so constructed as to allow for circumferential movement thereof relative to said pin, such that said first cam may be indexed through said first angle relative to said third cam by indexing of said manually engageable member by said operator.

9. A sewing machine in accordance with claim 8 wherein said indexing means includes an actuating plate disposed between said first and said second cam for transferring a predetermined fraction of the movement of said first cam to said second cam when said first cam is indexed.

10. In a sewing machine having a frame including a bracket arm, a needle carrying needle bar mounted in said frame for endwise reciprocation and sidewise movement relative to the direction of reciprocation, a main shaft journaled in said frame, a first, a second and a third stitch-pattern cam, said first and second cams each having a first number of substantially similar response-producing cam lobes similarly disposed about the surface thereof, said third cam having a second number of response-producing cam lobes disposed about the surface thereof, the lobes ofthe third cam being substantially the same configuration as the lobes of said first and second cams, a shaft rotatably driven from said main shaft about a single axis, said cams being mounted in superposed relationship on said driven shaft for rotation therewith, a cam tracking element carried by said frame for tracking the combined stitch-pattern response of said first, second and third cams sensed by said element, said first and second cams each having an indexing axis about which said first and second cams may be indexed angularly relative to said shaft, said indexing axes being substantially coincident with said single axis, means operably associated with said cams being so constructed and arranged for indexing at least said first and second cams angularly relative to each other and relative to the third cam to alter the combined stitch-pattern response of said cam surfaces, said indexing means including actuating means operably disposed between said first and second cams, said actuating means being constructed and arranged to be shifted into one of two positions whereupon in one position the cam lobes of said first and second cams are arranged to form a plurality of spaced continuous surfaces with selected cam lobes of said third cam for producing a stitch pattern, and in said second position said cam lobes of said first and second cams substantially are alined with certain of said third cam lobes for producing a second stitch pattern.

11. A sewing machine in accordance with claim 10 wherein said actuating means comprises a plate slidably mounted between said first and second cams for being shifted to either one of said two positions, said plate being provided with an aperture and a depending pin, a stud carried by one of said first and second cams. said aperture being in register with said stud, the other of said first and second cams includinga camming slot formed therein, said depending pin being in register with said slot and coacting with the walls thereof, so that when said one cam is indexed through a first prescribed angle said plate is slidably shifted from one of said two positions to the other of said positions thereby causing said pin to move said other cam about said shaft, said slot being disposed in said other of said cams fo'r indexing said other cam through a second prescribed angle when said one cam is indexed through said first prescribed angle such that any voids that may exist between the cam lobes forming the continuous surface will be substantially filled by the cam lobes of said first and second cams.

227g? UNITED S TAT ES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,54l, 981 Dated November 24, 19 0 Inventor(s) illiam AL Watson It is certified that error appears in the above-identified patent and that said Letters Patent; are hereby corrected as shown below:

" Column 3, line 63 "A should read Z Column 4, line 56 after "54" insert is carried on Column 5, line 9 "but, as" should read choice Column 8, line 42 "engageably" should read engageable Column 10, line 4 after "a" insert first Signed and sealed this 2L .th day of August 1971.

(SEAL) Attest:

EDWARD M.FLETCEER,JR. I WILLIAM E. SCHUYIER, JR. Attesting Officer Commissioner of Patents