US2887968A

US2887968A - Stitch adjusting mechanism

Info

Publication number: US2887968A
Application number: US687730A
Authority: US
Inventors: Benink Christiaan Jose Marinus; Wenz Herbert
Original assignee: GM Pfaff AG
Current assignee: GM Pfaff AG
Priority date: 1956-10-09
Filing date: 1957-10-02
Publication date: 1959-05-26
Anticipated expiration: 1976-05-26
Also published as: CH347065A; DE1031618B

Description

May 26, 1959 c. J. M. BENINK ETAL 2,837,968

STITCH ADJUSTING MECHANISM Filed Oct. 2, 1957 3 Sheets-Sheet l INVEN7'0P5 May 26, 1959 c. J. M. BENlNK ET AL 2,887,968

STITCH ADJUSTING MECHANISM 3 Sheets-Sheet 2 lNVE/VTOPS w M W May 26, 1959 c. J. M. BENINK ET AL I 2,887,968

STITCH ADJUSTING MECHANISM I Filed Oct. 2, 1957 3 Sheets-Sheet 3 AYWJW AGL'IVT United States Patent STITCH ADJUSTING MECHANISM ApplicationOctober 2, 1957, Serial No. 687,730 Claims priority, application Germany October 9, 1956 4 Claims. (Cl. 112-210) The present invention relates to sewing machines and is particularly concerned with the improvement of the stitch adjusting mechanism of the type disclosed in application Ser. No. 608,915, now Patent No. 2,844,114, to provide for controlling the length of the forward and the reverse stitch effected by the machine automatically.

It is therefore an object of the invention to provide automatic means for controlling the length of forward and rearward stitches made by the machine.

It is a further object of the invention to make possible the use of the operating lever for adjusting the stitch length also for setting of the automatic control and setting of the magnitude of the controlled stitch length..

In accordance with the invention a slide lever havingv a guiding slide portion and a free motion portion which is movable together with the abutment lever and a .connecting bar having a pin guided in said slide for transmitting the guiding impulses for the stitch length from the guide cam disk are provided, which levers can be coupled with one another by rotating a disk arranged coaxially with the stitch setting shaft and having an elongated aperture beyond thezero position of the stitch setting device for the automatic control of the forward and reverse stitch.

Further advantages and objects of the invention will become apparent from the following specification describing the invention with reference to an embodiment thereof illustrated in the accompanying drawings inwhich:

Fig. 1 shows a front view of a sewing machine incorporating the invention;

Fig. 2 is a section taken along line IIII in Fig. 1 drawn to an enlarged scale;

I Fig. 3 is a partial sectional view taken along line III-'- III in Fig. 2 showing the position of the disk for forward stitching;

Fig. 4 is a top view partly in section taken along line IV-IV of Fig. 3;

Fig. 5 is a sectional view along line VV'in Fig. 4 showing the disk in zero position; and t Fig. 6 is a section taken along line VIVI in Fig. 4 in which the disk is in position for automatically guiding the stitch setting mechanism. a

The sewing machine in accordance with Fig. lincludes the customary base plate 1, a standard 2 as well as arm portion 3 and a machine head 4. The arm shaft 5 is journalled in the arm 3. A balance wheel 6 is supported hollow shifting sleeve 31.

Patented May 26, 1959 2 feed dog advancing shaft 14 journalled in a boss 13 projecting from the base plate.

A sliding member 16 is secured to the cam follower bar 11 by means of a screw 15 and is received in the stitch setting slide 17 which is pivotally journalled by means of shaft screw 18 and sleeve 19 in the standard 2 (Fig. 3) which is provided for this purpose with a recess 20. Anarm 21 is provided on the slide 17 to which a draw bar 23 is pivotally connected by means of a collar screw 22.

The feed dog raising shaft 25 is journalled in a lug 24 in the base plate 1 which is connected in the usual manner to the dog raising cam (not shown) on the arm shaft 5 by way of a crank 26 and cam follower bar 27.

A boss 28 on the front side of the standard 2 is provided with a bore in which a bearing sleeve 30 is mounted to receive hollow shifting shaft 31 to theoutwardly projecting end of which the operating knob 32 is secured, while a sleeve 34 with the guide disk 35 is secured by means of a screw 33 tothe inwardly extending end of shaft 31. Disk 35'is provided with an aperture 36 (Fig. 3) presenting

curves

37 and 38 for determining the inner and outer limits, respectively, relative to the axis of rotation.

An oflset supporting arm 39 is fixedly secured by means of screws 40 to the bearing sleeve 30 (Fig. 4). This arm 39 extends through the aperture 41 in the housing into the standard 2. A stud 42 is provided on the free end of arm 39 on which the abutment lever 44- is journalled by means of a hub 43 and held in place by a lock ring 45. Lever 44 presents the abutment pin 46 (Fig. 3) which projects into the disk 35. The free end of the lever 44 is set off at an angle and is joined to the draw bar 23 by means of collar screw 47 (Figs. 2 and 4). v v The stitch setting slide 17 (Fig. 2) is provided with an arm 48 having'a bore 49 which is engaged by one end of a spring 50, the other end of which is secured to a hook member 51 which engages the recess 52 in a cage 53 of the standard '2. The spring tends to turn the slide 17 in a manner that the pin 46 of the lever 44 engages the curved edge 37 for the forward stitch in the guide disk 35.

A pin' 54 is secured to the angular end of the lever 44 (Figs. 4 and 5) which extends into the plane of the arm 55 of adjusting member 56 which is fastened to the clamping sleeve 57 which is securely fastened by means of set screw 58 to the stitch setting shaft 59 journalled in the The free end of shaft 59 is provided with a manipulating grip or lever 60.

v Adjusting member 56 is biased by a spring 61 (Figs. 4 and'5') which is hooked at one end into a bore 62 of a second lever arm 63 and at the other end around a groove i 64 in the stud 42. This turns member 56 counterclockwise as seen in Fig. 5 until the third lever arm 65 of the adjusting member 56 abuts the reduced end 66 of the stud 42.

For the automatic control of the forward and reverse stitching in accordance with the invention the aperture 36 on the end of the shaft 5 which projects from the housing, 9

of disk 35 is widened in a manner to permit clearance for movement of the abutment pin 46 on lever 44 towards the other side, so that pin 46 does not touch the two limit lines of the aperture portion 36'. The disk 35 is reinforced by means of a thin disk 67 secured thereto.

Disks

35 and 67 carry a pin 68 which is enabled during rotation of the

disks

67 or 35 in counterclockwise direction to enter a throat in connecting bar 69 (Figs. 3

and 6) in order to thus shift the connecting bar 69 about manner by the stitch setting lever 8 provided in the arm 5 its. axis of rotation 71 to the left as seen in Fig. 3. In this manner a pin 72 on connecting bar 69 is brought into engagement with a guiding slot 73 (Fig. 6) of a guide or slide lever 74 on hub 43, thus establishing operative connection between connecting bar 69 with stitch setting slide 3 17 by way of

levers

23, 44 and 74. Slot 73 is of the shape of a circular are having its center at the pivot axis 71. Toward the free end of lever 74 the arcuate slot 73 leads into an aperture 75 extending substantially perpendicularly to said slot and which constitutes the free wheeling portion of the slotted lever 74. The inner limit of the aperture 75 is defined by an arcuate edge, the center point of which is at the axis of rotation of lever 74. Fig. 3 illustrates the disengaged position of connecting bar 69 where the pin 72 rests against the arcuate border line of the aperture 75 under the pressure of the spring 76 which is disposed around the pivot axis 71.

The connecting bar 69 (Figs. 2, 3 and 4) is journalled at its upper end on pivot axle 71 which is secured in the lever arms of a U-shaped angular lever 77 which is journalled on a pivot axle 78 which, in turn, is secured to a bearing support 80 mounted by means of screws on the supporting plate of the machine. One arm 81 of the angular lever 77 is connected to one end of a guide link 82 which is twisted by a 90 angle, the other end of which is secured to the bent up arm 83 of a rocking lever 84. This rocking lever 84, in turn, is pivotally mounted by means of a collar screw 85 and presents a further arm 86 which is also angularly bent and presents a follower 87 which is in engagement with the guide cam disk 88 for controlling the forward and reverse stitching of the machine and which is provided in a known manner in the nest of cams 89 for the lateral deflecting of the needle bar, which cams are driven by the arm shaft 5,

The setting of the desired stitch length is effected in a manner known per se by rotating the control knob 32 from zero position of Fig. clockwise, which causes the abutr ment 46 to slide along the outer limit curved edge 37 because the abutment lever 44 is biased upwardly by spring 50 by way of draw bar 23 and the stitch setting slide 17.

For setting up the corresponding reverse stitch of equal length the manual lever 60 is rotated clockwise counter the force of spring 61 as viewed in Fig. 3, until arm 55 of the adjusting member 56 presses lever 44 downwardly, to a sufiicient extent to cause abutment 46 to contact the reverse stitch guide edge 38. As the lever 60 is released the adjusting member 56 returns to its initial position under the tension of spring 61 which brings the abutment 46 again in engagement with the forward stitch guide edge 37.

During the setting of the stitch length described in the foregoing passage, the pin 72 on the connecting bar 69 is held in the free drive portion 75 of'the slide lever 74. Consequently, no coupling takes place between the connecting bar 69 and the slide lever 74.

For the automatic control of the forward and reverse stitch the control knob 32 and thereby disks 35 and 67 are rotated counterclockwise from the zero position in Fig. 5 causing the abutment 46, on the one hand, to enter the widening section of the aperture 36 and, on the other hand, causing an angular clockwise shift of the connecting bar 69 about its axis of rotation 71 as a result of the en trance of pin 68 on the

disks

35 and 67 into throat 70 of the connecting bar 69. In turn the pin 72 on the connecting bar 69 is caused to enter slot 73 of the guide or slide lever 74 (Fig. 6), thereby coupling them together so that the guiding impulses derived from the guide disk 88 are applied to the slide lever 74 and thence to the stitch setting slide 17. The impulses applied to the stitch setting slide 17 increase in magnitude as the pin 72 is moved further into the slot 73. This relationship is only maintained, however, with the arcuate slot 73 described hereinabove. By forming the slot 73 differently or even by differently positioning the slide lever 74 in relation to the pivot axis 71, it is possible by suitably shifting the pin 72 in the slot 73 to transfer the impulses derived from guide the embodiment illustrated in the drawings, We do not wish to be limited thereto, but what we desire to protect by Letters Patent is set forth in the appended claims.

We claim:

1. Stitch adjusting mechanism for a sewing machine having an arm shaft, a stitch setting cam and a dog raising cam on said arm shaft, a feed dog advancing shaft, a setting cam follower bar connecting said advancing shaft to said setting cam, a feed dog raising shaft, a raising cam follower bar connecting said dog raising shaft to said dog raising cam, a stitch guiding cam operatively geared to said arm shaft and a guiding cam follower pivotally mounted adjacent said guiding cam in operative engagement therewith, a guided slide member pivotally connected to said setting cam follower bar and a stitch setting slide pivotally mounted in the machine housing in engagement with said slide member; said mechanism including an abutment lever pivotally mounted at one end on a support in the machine housing and connected at the other end to a draw bar linked to said stitch setting slide and presenting an abutment pin, a guide lever pivotally mounted for movement with said abutment lever having a guiding portion and a free motion portion, a stitch setting shaft rotatably mounted in the standard of the machine presenting an external operating knob, a guide disk secured to said stitch setting shaft having an elongated aperture defining forward and reverse stitch guiding curves for engagement by said abutment pin, an impulse transmission bar pivotally linked to said guiding cam follower having a stud and a slotted throat portion, said guide disk presenting a pin adapted upon rotation of said disk to enter said slotted throat portion and advance said stud into said guiding portion thereby coupling said impulse transmission bar by way of said guide lever, said abutment lever and said connecting link to said stitch setting slide.

2. Stitch adjusting mechanism for a sewing machine having an arm shaft, a stitch setting cam and a dog raising cam on said arm shaft, :1 feed dog advancing shaft, a setting cam follower bar connecting said advancing shaft to said setting cam, a feed dog raising shaft, a raising cam follower bar connecting said dog raising shaft to said dog raising cam, a stitch guiding cam operatively geared to said arm shaft and a guiding cam follower pivotally mounted adjacent said guiding cam in operative engagement therewith, a guided slide member pivotally connected to said setting cam follower bar and a stitch setting slide pivotally mounted in the machine housing in engagement with said slide member; said mechanism including an abutment lever pivotally mounted at one end on a support in the machine housing and connected at the other end to a draw bar linked to said stitch setting slide and presenting an abutment pin, a guide lever pivotally mounted for movement with said abutment lever having a guiding portion and a free motion portion, a stitch setting shaft rotatably mounted in the standard of the machine presenting an external operating knob, a guide disk secured to said stitch setting shaft having an elongated aperture defining forward and reverse stitch guiding curves for engagement by said abutment pin, an impulse'transmission bar pivotally linked to said guiding cam follower having a stud and .a slotted throat portion,

' said guide disk presenting a pin adapted upon rotation of cam 88 proportionately for the control of the stitch length" of .the forward and reverse stitches.

Having now described our invention with reference to said disk to enter said slotted throat portion and advance said stud into said guiding portion thereby coupling said impulse transmission bar by way of said guide lever, said abutment lever and said connecting link to said stitch setting slide, and a spring biased reversing lever having an arm adapted to engage a member on said abutment lever and operative to effect engagement of said stud with said reverse stitch setting curve, said reversing lever being supported on a shaft extending through said stitch setting shaft and presenting an exterior operating lever.

3. Stitch adjusting mechanism for a sewing machine having an arm shaft, a stitch setting cam and a dog 'raising cam on said arm shaft, a feed dog advancing shaft, a setting cam follower bar connecting said advancing shaft to said setting cam, a feed dog raising shaft, a raising cam follower bar connecting said dog raising shaft to said dog raising cam, a stitch guiding cam operatively geared to said arm shaft and a guiding cam follower pivotally mounted adjacent said guiding cam in operative engagement therewith, a guiding slide member pivotally connected to said setting cam follower bar and a stitch setting slide pivotally mounted in the machine housing in engagement with said slide member; said mechanism including an abutment lever pivotally mounted at one end on a support in the machine housing and connected at the other end to a draw bar linked to said stitch setting slide and presenting an abutment pin, a guide lever pivotally mounted for movement with said abutment lever having a guiding portion and a free motion portion, a stitch setting shaft rotatably mounted in the standard of the machine presenting an external operating knob, a guide disk secured to said stitch setting shaft having an elongated aperture defining forward and reverse stitch guiding curves for engagement by said abutment pin, an impulse transmission bar pivotally linked .to said guiding cam follower having a stud and a slotted throat portion, said guide disk presenting a pin adapted upon rotation of said disk to enter said slotted throat portion and advance said stud into said guiding portion thereby coupling said impulse transmission bar by way of said guide lever, said abutment lever and said connecting link to said stitch setting slide, and a spring biased reversing lever having an arm adapted to engage a member on said abutment lever and operative to effect engagement of said stud with said reverse stitch setting curve, said reversing lever being supported on a shaft extending through said stitch setting shaft and presenting an exterior operating lever, said guiding portion being in the form of a slot extending longitudinally of said guide lever and said free motion portion being an aperture defined endwise of and extending transversely of said slot and permitting free movement of said stud and of said impulse transmission bar.

4. Stitch adjusting mechanism for a sewing machine having an arm shaft, a stitch setting cam and a dog raising cam on said arm shaft, a feed dog advancing shaft, a setting cam follower bar connecting said advancing shaft to said setting cam, a feed dog raising shaft, a raising cam follower bar connecting said dog raising shaft to said dog raising cam, a stitch guiding cam operativcly geared to said arm shaft and a guiding cam follower pivotally mounted adjacent said guiding cam in operative engagement therewith, a guided slide member pivotally connected to said setting cam follower bar and a stitch setting slide pivotally mounted in the machine housing in engagement with said slide member; said mechanism including an abutment lever pivotally mounted at one end on a support in the machine housing and connected at the other end to a draw bar linked to said stitch setting slide and presenting an abutment pin, a guide lever pivotally mounted for movement with said abutment lever having a guiding portion and a free motion portion, a stitch setting shaft rotatably mounted in the standard of the machine presenting an external operating knob, a guide disk secured to said stitch setting shaft having an elongated aperture defining forward and reverse stitch guiding curves for engagement by said abutment pin, an impulse transmission bar pivotally linked to said guiding cam follower having a stud and a slotted throat portion, said guide disk presenting a pin adapted upon rotation of said disk to enter said slotted throat portion and advance said stud into said guiding portion thereby coupling said impulse transmission bar by way of said guide lever, said abutment lever and said connecting link to said stitch setting slide and a spring biased reversing lever having an arm adapted to engage a member on said abutment lever and operative to effect engagement of said stud with said reverse stitch setting curve, said reversing lever being supported on a shaft extending through said stitch setting shaft and presenting an exterior operating lever, said guiding portion being in the form of a slot extending longitudinally of said guide lever and said free motion portion being an aperture defined endwise of and extending transversely of said slot and permitting free movement of said stud and of said impulse transmission, said slide member and said impulse transmission bar being spring biased. 7

References Cited in the file of this patent UNITED STATES PATENTS 1,611,372 Rader Dec. 21, 1926 2,685,266 Pagni Aug. 3, 1954 2,704,986 Pagni Mar. 29, 1955 2,751,868 Schwab June 26, 1956 FOREIGN PATENTS 27,985 Great Britain Dec. 19, 1907 756,403 Great Britain Sept. 9, 1956