US3036535A

US3036535A - Sewing machine work feed adjusting device

Info

Publication number: US3036535A
Authority: US
Inventors: Earl F Dunn; Koszta Elmer
Original assignee: Singer Co
Current assignee: Singer Co
Priority date: 1959-07-28
Filing date: 1959-07-28
Publication date: 1962-05-29
Anticipated expiration: 1979-05-29

Description

May 29, 1962 E. F. DUNN ET AL 3,036,535

SEWING MACHINE WORK FEED ADJUSTING DEVICE Filed July 28, 1959 INVENTORS Earl E Dunn Elmer Koszfa 2. V ATTORNEY WITNESS United States atent 3,036,535 SEWING MACHINE WORK FEED ADJUSTING DEVICE Earl F. Dunn, Monroe, and Elmer Koszta, Fairfield,

Conn., assignors to The Singer Manufacturing Company, Elizabeth, N.J., a corporation of New Jersey Filed July 28, 1959, Ser. No. 830,018 1 Claim. (Cl. 112-210) This invention relates to sewing machines having work feeding mechanisms capable of adjustment to vary the length of stitches and, more particularly, to a device for at will positioning and maintaining the work feeding mechanism at a selected stitch length.

It is an object of this invention to provide a novel stitch length adjusting device for a sewing machine with which a desired stitch length adjustment may be made easily and conveniently, and the adjusting device locked in selected position requiring only the use of one hand of a machine operator to accomplish both the adjusting and the locking.

Another object of this invention is to provide a clamping device for securing a stitch length adjusting member in a selected position in which the operation of the clamping device cannot influence the position of adjustment of the stitch length adjusting device.

With the above and other objects and advantages in view, this invention is described hereinbelow and illustrated in the accompanying drawings of a preferred embodiment in which:

FIG. 1 represents a vertical transverse cross sectional view of the standard portion of a conventional sewing machine, illustrating the regulating and adjusting devices for a conventional drop feed mechanism and having the present invention applied thereto,

FIG. 2 is an enlarged cross sectional view taken substantially along line 2-2 of FIG. 1, and

FIG. 3 is a cross sectional view taken substantially along line 3-3 of FIG. 2.

Illustrated in FIG. 1 is a conventional type sewing machine frame including a hollow standard 11 rising from a bed 12. Journaled lengthwise in a bracket arm (not shown) and passing through the upper part of the standard is a main drive shaft 13 which serves in the usual manner to actuate the stitch forming instrumentalities of the sewing machine.

The mechanism disclosed in the sewing machine frame of FIG. 1 is that which generates and controls the feed advance and return motions of a four-motion or drop feed mechanism. By four motion or drop feed is meant that in which a feed dog rises into engagement with the work, advances in the direction of feed while raised, drops out of engagement with the work beneath the level of the bed 12 or a throat plate thereon (not shown), and returns while so dropped.

Indicated at 14 in FIG. 1 is a feed advance and return rock shaft journaled beneath the bed 12. A rock arm 15 fast on the feed advance and return rock shaft is pivoted to a pitman 16 which extends upwardly through the hollow standard and is formed with bifurcations 17 embracing a slide block 18 which is journaled on an eccentric 19 fast on the main drive shaft 18.

Pivoted to the pitman 16 on a pin 20 is an anchor link 21 which is anchored on a pivot pin 22 carried on an adjusting block 23 fulcrumed on the pivot pin 24 in a bearing lug 25 formed inside the hollow standard.

Pivotally carried on a pin 26 secured in the adjusting block 23 is one extremity of a connecting link 27 pivoted. at its other extremity by means of a pin 28 to feed adjusting lever 29. The feed adjusting lever is fulcrumed on a pin 30 secured between spaced abutments 3 1 formed at the rear of the hollow standard and extends through a vertical slot 32 formed in the front wall of the hollow standard, outwardly of which the feed adjusting lever 29 is formed with a hand grip portion 33.

By means of the control lever 29, the connecting link 27, and the block 23, the sewing machine operator may at will effect changes in the position of the anchor link 21 with respect to the pitman 16, whereby the extent of oscillatory motion imparted to the feed advance and return rock shaft 14 may be regulated and the direction of oscillation may be changed to reverse the direction of feed of the work being stitched. Thus, when the anchor link 21 is shifted into substantial alignment with the pitman, no appreciable motion will be imparted to the feed rock shaft 14 and no work feeding will occur. When the lever 29 is raised, the pivot pin 22 joining the anchor link 21 to the adjusting block 23 will be shifted to the left of the pitman 16, as viewed in FIG. 1, and motion will be imparted to the feed rock shaft 14 to effect work feeding movements in the normal forward direction. Similarly, when the lever 29 is depressed, the pivot pin 22 will be shifted to the opposite side of the pitman 16 and the work feeding movements will be reversed.

Threaded into the front wall of the sewing machine standard 1 1 is a feed length adjusting screw 4! formed with a rounded extremity 41 extending between angularly arranged

abutment surfaces

42 and 43 formed on the adjusting block 23. The

surfaces

42 and 43 are arranged on the block 23 such that when the angle defined therebetween is bisected by the axis of the adjusting screw 48, the feed regulating anchor link 21 will be disposed in a position corresponding to that of zero stitch length. In any position of adjustment, the adjusting screw 40 will limit block 23 to an equal amount on either side of the Zero stitch length position and, therefore, the maximum stitch length at any setting will be the same on both the forward and reverse directions of feed.

The feed regulating lever 29, being carried on a fulcrum pin 30 is constrained such that all points on the lever move in fixed parallel planes perpendicular to the axis of the fulcrum pin 30. A spring 45 biases the feed adjusting lever 29 into raised position determined by the abutment surfaces 42 and the adjusting screw 40, as illustrated in FIG. 1, which corresponds to the maximum stitch length in the forward direction of feed. The operator, by simply depressing the hand grip 33 until the abutment surface 43 engages the end 41 of the adjusting screw, can automatically set the mechanism in position to feed the work in the reverse direction and with the same stitch length.

It is desirable with feed regulating mechanisms such as illustrated in the drawings to provide a means for selecting one particular setting of the adjusting lever 29, and for locking the mechanism in the particular setting selected. For this purpose, the slot 32 in the sewing machine standard is provided with an escutcheon plate 5%) secured in place by screws 51 and formed with a slot 52 opening into the machine standard slot 32. The escutcheon plate is also provided with a side edge 53 disposed in a plane substantially perpendicular to the axis of the fulcrum pin 30, i.e., parallel to the fixed planes in which the adjusting lever is constrained to move. A pointer 54 secured by screws 55 atop of the adjusting lever 29 is preferably resilient and urged upwardly by a screw 56 threaded into the adjusting lever such that the pointer may be adjusted to register accurately with indicia (not shown) on the escutcheon plate to represent the length of stitch corresponding to the position of the adjusting lever 29.

Loosely fastened to the adjusting arm 29 on a fastening screw 60 beneath the hand grip 33 is a clamp arm 61 formed with an arched finger 62 extending over and snuggly embracing a circular flange 63 formed on a clamp screw 64 threaded in the adjusting arm 29. The clamp arm is formed at the free extremity with an offset clamping finger 65 disposed adjoining the side edge 53 of the escutcheon plate.

The clamp finger 65 is, therefore, carried not only into clamped engagement with the side edge 53 of the escutcheon plate 50 but also out of engagement therewith by the fiange 63 of the clamp screw which carries the arched finger 62 formed thereon.

The clamp screw 64 is disposed preferably between the hand grip portion 33 of the feed adjusting and machine standard and is thus conveniently accessible for tightening or loosening with one hand without loss of control of the position of the adjusting lever. With the palm of the hand on the hand grip 33, the thumb and fingers of the hand are free and available for tightening and loosening the screw.

The clamping action of the clamp finger 65 against the side edge 52 of the escutcheon plate occurs in a direction substantially perpendicular to the planes of motion of the feed adjusting lever. The action of the clamp finger 65 in gripping the side edge 52 of the escutcheon will, therefore, not exert any forces tending to shift the adjusting arm 29 either up or down. The external shape of the escutcheon plate is preferably arcuate to conform to the are described by the pointer 54, however, the shape of the escutcheon plate is of little consequence in this respect and may vary considerably from the shape of the path of motion of the pointer without having any efiect upon the accuracy with which the adjusting arm 29 can be clamped in place.

The attribute of the present invention to permit the stitch length adjusting arm to be clamped easily and accurately in selected position is particularly advantageous in selecting small stitch lengths on a zigzag sewing machine where the appearance of the seam is influenced to a large extent by the spacing of successive stitches.

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

In a work feeding mechanism for a sewing machine having a casing, 21 shiftable feed regulating lever pivotally supported for oscillatory movement about an axis fixed in the sewing machine casing and protruding outwardly through a clearance slot in the casing, a substantially fiat horizontal hand grip portion formed at the free extremity of said feed regulating lever protruding out of the machine casing, means for locking said feed regulating lever in selected position of adjustment comprising an escutcheon plate secured on said sewing machine casing over said clearance slot, an abutment portion of uniform width on said escutcheon plate at one side of said clearance slot, a clamp arm loosely secured on said feed regulating lever, clamp screw means operatively engaging and clamp arm for shifting said clamp arm toward and away from said feed regulating lever in a direction parallel to the pivotal axis of said feed regulating lever, means threadedly engaging said clamp screw on said feed regulating lever between the hand grip portion of said feed regulating lever and the machine casing so as to be immediately engageable by the operation fingers when the palm of the operators hand touches the hand grip portion, and a clamp finger extending from said clamp arm and on the opposite side of said escutcheon abutment portion from said feed regulating lever.

References Cited in the file of this patent UNITED STATES PATENTS 373,391 Daggett Nov. 15, 1887 1,951,922 Cantrell Mar. 20, 1934 2,723,635 Matuzas Nov. 15, 1955 2,725,023 Ayres Nov. 29, 1955 2,877,727 Graesser Mar. 17, 1959 FOREIGN PATENTS 358,192 France Jan. 3, 1906