US2970556A

US2970556A - Stitch length adjusting means for sewing machines

Info

Publication number: US2970556A
Application number: US716696A
Authority: US
Inventors: Ralph E Johnson
Original assignee: Singer Co
Current assignee: Singer Co
Priority date: 1956-01-30
Filing date: 1958-02-21
Publication date: 1961-02-07
Anticipated expiration: 1978-02-07
Also published as: GB802464A; FR1170243A; GB888606A; CH351485A; CH368695A; BE554471A

Description

R. E. JOHNSON 2,970,556 STITCH LENGTH ADJUSTING MEANS FOR SEWING MACHINES Feb. 7, 1961 Filed Feb. 21, 1958 5 I. 2 ERWWMS 5 ma Irin INVENTOR. Ralph E. Johnson BY ATTORNEY Fig WITNESS 44mg;

STITCH LENGTH ADJUSTING MEANS FOR SEWING MACHINES Ralph E. Johnson, Mountainside, N.J., assiguor to The Singer Manufacturing Company, Elizabeth, N.J., a corporation of New Jersey Filed Feb. 21, 1958, Ser. No. 716,696

6 Claims. (Cl. 112-210) This application is a continuation-in-part of application Serial No. 562,096, filed January 30, 1956, which is being abandoned in favor of the present application.

The present invention relates to a feeding mechanism for sewing machines and has for a primary object to provide a new and improved stitch length adjusting means for the feeding mechanism of a sewing machine.

The usual feeding mechanism of a family type sewing machine includes a pivoted block having a guide channel or slideway that cooperates with a slide block on the feed advance. actuating pitman of the feeding mechanism to impart endwise motion to the pitman upon oscillation thereof. The amount of the endwise motion of the pitman determines the feed advance stroke of the feeding mechanism and, in turn, is determined by the setting of the pivot block. Manual adjustment of the setting of the pivot block is provided by means of a stitch length adjusting lever secured to the pivot block and extending through a slot in the frame of the machine, or more commonly, through a slot in a stitch indicator plate, to Where it is conveniently accessible to the operator. To indicate the setting of the mechanism, the stitch length adjusting lever cooperates with indicia on the frame or stitch indicator plate adjacent to the side edge of the slot.

During normal operation of the machine, it is customary to swing the actuating lever momentarily to the reverse stitching position for back tacking to lock the end of a seam and then to return it to its forward feed position. To facilitate returning the leverto the same setting after back tacking that it had before, the lever is provided with an adjustable stop that cooperates with the stitch indicator plate to limit pivotal movement of the lever to a predetermined setting.

In the usual stitch length adjusting means of family sewing machines it is diflicult to obtain an accurate fine adjustment since movement of the lever about the zero position is so critical. An accurate exceedingly fine adjustment of the feeding mechanism is required for such :position of zero feed. The pivot block is frictionally held in its adjusted position and in view of the mechanics of the connections to the feeding element, the setting thereof is normally not affected during operation of the machine. However, with a long stitch length, the pivot .block 7 is tilted at a maximum relatively to the path of oscillation of the slide block'ltl and there is a corresponding maximum reaction upon the pivot block 7 tending to turn it into alignment with the path of movement of the slide block it). This reaction is also directly proportional to the thickness of the workin that a greater effort is required to feed heavy material than to feed light Work. Experience has shown that. when sewing heavy Patent ice work with a long stitch the setting of the pivot block may be disturbed. Since a long stitch length is normally desired when sewing heavy work, the sewing of such work on a family sewing machine is difiicult.

In accordance with the above, the present invention is directed specifically to the provision of a stitch length adjusting means for family sewing machines which will afford means for adjustably limiting the pivotal movement of the stitch length adjusting lever and will clearly indicate the setting of the same and, at the same time, will facilitate obtaining exceedingly fine adjustments of the feeding mechanism which is required in the very short stitch length settings and will also hold the stitch length setting when sewing with a long stitch length on heavy fabric.

Further objects of the invention are to provide a stitch length adjusting means having the above advantages but which, at the same time, is simple and economical, easy to operate, dependable, durable and economical.

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 function, operation, construction and advantages of it when read in conjunction with the accompanying drawings in which:

Fig. 1 is a fragmentary front elevational view of a sewing machine embodying the present invention.

Fig. 2 is a vertical sectional view taken substantially on the line 2-2 of Fig. 1.

Fig. 3 is a sectional view taken substantially on the line 3-3 of Fig. 2.

Fig. 4 is a view similar to Fig. 2 but illustrating the parts in a difierent position.

Fig. 5 is a sectional view taken substantially on the line 5--5 of Fig. 3.

With reference to the drawings, there are illustrated fragmentary portions of the frame of a sewing machine including a standard 1 and a bracket arm 2. The feed ing mechanism of the machine is of a well-known construction comprising a feed-advance pitman 3' arranged vertically in the standard 1 and having a fork 4 at its upper end. The fork 4 embraces an eccentric 5 on the main shaft 6 which is journaled longitudinally in the bracket-arm 2. It is the endwise motion of the pitman 3 that determines the feed-advance motion of the feed stroke. Upon oscillation of the pitman 3 by the eccentric 5, endwise motion is imparted to the pitman by an adjustable mechanism including a pivot block 7 pivoted to the standard 1 by a pivot screw 8 and having a guide channel or slideway 9 in which is slidably mounted a slide block it! pivotally secured to the pitman 3 by a screw 11. The amount of the endwise motion imparted to the pitman 3 depends upon the orientation of the guide channel 9 with respect to the center of oscillation of the pitman, which is at its lower end. When the guide channel 9 is tangential to the path of oscillation of the slide block 10, substantially no endwise motion is imparted to the pitman 3 and there is thus no feed advance motion. This is the position of zero feed. When the guide channel 9 is tilted in one direction, forward motions will be imparted to the pitman 3 and when tilted in the opposite direction, reverse feed motions will be imparted to the pitman 3 the more the guidechannel 9 is tilted, the greater will be the feed motion.

The pivot block 7 is manually adjusted about its pivot 8 by a stitch length adjusting lever or rod 12 secured at one in a bore in the pivot block 7 by a screw 13. The other or free end of the lever 12 extends through an opening 14 in the standard 1, the opening 14 being partially closed by a stitch indicator plate secured to the standard 1 by screws 16 and having a vertically elongated slot 17 to accommodate the lever 12.

Adjacent to the point of zero or no-feed adjustment of the lever 12 there is provided in the plate 15 at one side of the slot 17 a l-shaped concave depression 18 having side walls or surfaces that are inclined lengthwise of the slot 17 out of the plane of the plate 15 and converge at an apex 19 that is at the zero setting of the lever 12.

Extending axially inwardly from the free end of the lever 12 is a slot 2t? in which is slidably mounted a planar slide element 21 having a lateral finger 22 extending beyond the periphery of the lever 32 at the side adjacent to that edge of the slot 17 having the depression 18. The slide element 21 has the outer end thereof threaded to cooperate with internal threads in an axial bore 23 of a thumb nut 24. The nut 24 is journaled for rotation on the reduced diameter outer end of the lever 12 and is held against axial movement between a shoulder 25 on the lever 12 and a retaining screw 26 threaded into the end of the lever 12, a washer 27 being disposed between the nut 24 and screw 26.

In operation, the lever 12 is adapted to be moved manually along the slot 17 in the usual manner to pivot the block 7 with its channel 9, thereby varying the amount of endwise movement imparted to the pitman 3 upon oscillation of the same with the consequent variations in the feed stroke. The finger 22 which is adjusted axially of the lever 12 by means of the nut 24 will cooperate with the adjacent side of the slot 17 outside the depressionl? to form an adjustable stop for limiting. the manipulation of the lever 12 and at the same time, will cooperate with indicia on the plate 15 to indicate the setting of the lever 12. Thus, once a feed setting has been established, which setting will be indicated by cooperation of the finger 22 With indicia provided on the plate 15, the stitching may be reversed for back-tacking by shifting the lever 12 to the other side of the center position and conveniently to its original position. To obtain an accurate fine setting of the feed the lever 12 is moved along the slot 17 to bring the finger 22 into cooperation with the side walls of the depression 18. The finger 22 is then movedaxially of the lever 12 by turningthenut 24 and with the finger cooperating with the side edge of the depression 18 in a cam-like fashion, the lever 12 will be moved a minute amount.

Adjacent to the six-stitches per inch setting of the lever 12, which is the maximum obtainable stitch length, there is provided. in the plate 15 a second concave depression 28 at the same side of the slot 17 as the depression 18 and in which the finger 22 is adapted to be moved by turning the nut 24. The depression is so formed that when the finger 22 is seated therein, the lever 12 is locked against movement thus precluding the possibility that it will be forced away from this setting during the operationof the machine.

Numerous, 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 modi fications which do not depart from the spirit of the invention are intended to be included within the scope of theappende'd claims.

Having thus set forth the, nature of this invention, what I claim herein is:

' l.: In the feeding mechanism of a sewingmachine inof the opening, said lever having a slot extending axially inwardly from the free end thereof, a slide element slidably mounted in said slot and having a finger extending laterally from said lever into cooperation with said side edge of the opening and the depression therein, a manually rotatable member mounted upon the free end of said lever for rotation, means for confining said rotatable member against axial movement, and operative connections between said rotatable member and said slide element for shifting said slide element axially of said lever upon rotation of the rotatable member, said laterally extending finger on said slide element being arranged to cooperate with the side edge of the opening adjustably to limit the pivotal movement of the lever and to'cooperate with the inclined surfaces of the depression in a cam-like fashion to effect a fine adjustment of the lever upon movement of the slide element axially of the lever;

2. In the feeding mechanism of a sewing machine having a frame, a block pivoted to said frame and having a channel for slidably receiving an element of an oscillating feed advance pitman and for imparting endwise motion to said pitman upon oscillation thereof, said frame having an opening, a plate for closing said opening and having an elongated slot arranged perpendicular to the pivot axis of said block and a concave depression at one edge of the slot having surfaces inclined lengthwise of the slot out of the plane of said plate, and tilting means for adjusting said block about its pivot to vary the endwise motion imparted to the feed-advance pitman upon oscillation thereof, said tilting means comprising'a lever secured at one end to said block and having a free end extending through the slot in said plate whereby the free end of said lever may be manually grasped forshifting said lever lengthwise of the slot, said lever having a slot extending inwardly from the free end thereof, a slide element arranged, in the slot in said lever for sliding movement axially of said lever, said slide element having I a finger extending laterally from said lever into engagement'with the inclined surfaces of the depression in said plate and the adjacent side edge of the slot, a manually rotatable member mounted for rotation upon the free end of said lever, means for confining said rotatable member against axial movement, and cooperating threads on said rotatable member and said slide element for shifting said .slide element axially of said lever upon rowith the inclined surfaces of the depression in a camlike fashion to effect a fine adjustment of the lever upon movement of the slide element axially ofthe lever.

3. In the feeding mechanism of a sewing machine having a frame, a block pivoted to said frame and having a channel for slidably receiving an element of an oscillating feed advance pitman and for imparting endwise motion to said pitman upon oscillation thereof, said frame having an opening, a plate for closing said opening and having an enlongatedslot arranged perpendicular to the pivot axis of said block, and tilting means for adjusting said block about its pivot to vary the endwise motion imparted to the feed-advance pitman upon oscillation thereof, said tilting means comprising a'lever secured at one end to said block and having a free end extending through the slotin. said plate whereby the free end of-said lever may be manually grasped'for shifting said lever lengthwise of: the slot, said lever having a slot extending wardly from the free end thereof, a slide element arranged in, the slot in said lever for sliding movement axially of said lever; said slide element having a finger extending laterally from said lever into engagement with the adjacent side edge of' the slot, a manually rotatable member mounted for rotation upon the free end-of said lever, means for confining said rotatable member against axial movement, and cooperating threads on said rotatable member and said slide element for shifting said slide element axially of said lever upon rotation of said rotatable member, said laterally extending finger on said slide element being arranged to cooperate with the side edge of the slot in the plate adjustably to limit the pivotal movement of the lever.

4. In the feeding mechanism of a sewing machine including a frame having an opening and a stitch length adjustment lever having a free end extending through said opening to where it is conveniently accessible to the operator, said lever being adapted to adjust the feeding mechanism between zero and a maximum stitch length upon pivotal movement thereof, a stitch indicator plate disposed over said opening and having a slot through which said lever extends, said slot having a side edge arranged parallel and closely adjacent to the path of travel of said adjusting lever, said plate having a first and a second concave depression in the side edge thereof, said first depression being disposed adjacent to the point on said plate corresponding to the zero stitch length setting of said lever and defining surfaces inclined lengthwise of said side edge, said second depression being disposed adjacent to the point on said plate corresponding to the maximum stitch length setting of said lever, said lever having a slot extending axially inwardly from the free endthereof, a slide element mounted in said slot and having a finger extending laterally from said lever into cooperation with said side edge of the opening and the depressions therein, a manually rotatable member mounted upon the free end of said lever for rotation, means for confining said rotatable member against axial movement, and operative connections between said rotatable memher and said slide element for shifting said slide element axially of said lever upon rotation of said rotatable memher, said laterally extending finger being adapted to cooperate with the side edge of the opening adjustably to limit the pivotal movement of the lever, to cooperate with the inclined surfaces of the first depression in a cam-like fashion to effect a fine adjustment of the lever upon movement of the slide element axially of said lever, and to cooperate with the second depression to lock said lever against pivotal movement.

5. Stitch length adjusting means for sewing machines comprising a stitch indicator plate having an elongated slot, a stitch length adjusting lever extending through the slot andadapted to be shifted along the slot in opposite directions from a center position defined by the zero stitch length setting of said lever to provide for forward and reverse settings and to vary the setting from zero to a maximum as said lever is moved away from said center position, said plate having a side edge adjacent to said slot arranged parallel and closely adjacent to the path of travel of said lever, a finger extending laterally from said lever for engaging said side edge, and means for manually shifting said finger axially of said lever, said plate at the portion adjacent to said side edge being substantially planar with a concave V-shaped depression formed therein in the area immediately adjacent to the zero stitch length setting of said lever with the base of said depression at the Zero stitch length setting and presenting inclined surfaces lengthwise of the slot, said laterally extending finger being arrangedto cooperate with the planar portion of said plate adjacent to said side edge in the range of normal stitch lengths and with the inclined edges of said depression in the range of fine stitch lengths adjustably to limit the pivotal movement of the lever and to cooperate with the inclined surfaces of the depression in a cam-like fashion to eifect a fine adjustment of the lever upon movement of the finger axially of the lever.

6. In the feeding mechanism of a sewing machine having a frame, a block pivoted to said frame and having a channel for slidably receiving an element of an oscillating feed advance pitman and for imparting endwise motion to said pitman upon oscillation thereof relatively to said block with the endwise motion imparted to said pitman being variable between zero and a maximum upon pivotal movement of said block, said frame having an opening, a plate, for closing said opening and having an elongated slot including a side edge arranged perpendicular to the pivot axis of said block, tilting means for adjusting said block about its pivot axis comprising a lever secured at one end to said block and having a free end extending through the slot in said plate whereby the free end of said lever may be manually grasped for shifting said lever lengthwise of said slot, a finger slidably mounted on the free end of said lever for movement axially thereof and extending laterally from said lever for cooperating with the side edge of said slot to limit the pivotal movement of said lever, and means for moving said finger axially of said lever, said plate having a concave depression in said side edge of the slot at the point engaged by said finger when said lever is moved adjacent to the maximum stitch length setting, and in which said finger is adapted to be seated to lock said lever against pivotal movement.

References Cited in the file of this patent UNITED STATES PATENTS 1,397,071 Becker Nov. 15, 1921 2,525,578 Austlid Oct. 10, 1950 FOREIGN PATENTS 634,711 Germany Sept. 2, 1936 634,748 Germany Sept. 2, 1936 697,934 Germany Oct. 28, 1940 732,820 Germany Mar. 12, 1943