US2619924A

US2619924A - Sewing machine attachment

Info

Publication number: US2619924A
Application number: US169845A
Authority: US
Inventors: Robert W Burgess
Original assignee: Greist Manufacturing Co
Current assignee: Greist Manufacturing Co
Priority date: 1950-06-23
Filing date: 1950-06-23
Publication date: 1952-12-02
Anticipated expiration: 1969-12-02

Description

Dec. 2, 1952 R. w. BURGESS SEWING. MACHINE ATTACHMENT Filed June 25, 1950 Bnnentor (Ittornegs Patented Dec. 2, 1952 SEWING MACHINE ATTACHMENT Robert W. Burgess, Bridgeport, Conn, assignor to The Greist Manufacturing Company, New Haven, Conn, a corporation of Connecticut Application Juuc 23, 1950, Serial No. 169,845

This invention relates to sewing machine attachments and more particularly to an improvement in attachments which are adapted for use with the ordinary household sewing machine, while the improvements are illustrated and described as being applied to an attachment for buttonholers or devices for forming buttonholes in the piece of material.

Attachments of this type are normally secured to the presser bar of the sewing machine and an actuating lever is provided which is connected to the needle bar so that the mechanism of the attachment is actuated by the reciprocations of the needle bar. In the case of a buttonhole attachment such as described (for example, an attachment similar to that shown in Almquist Patent No. 2,482,607, granted September 20, 1949) a feed plate is pivoted to the frame of the attachment and arranged to be oscillated by the pivoted actuating lever. Upon this feed plate is mounted a work-holding foot or clamping member which engages the work and moves it laterally in zig-zag fashion so as to effect the required stitching in the work. The oscillations of the feed plate are effected by means of a cam member rotatably carried by the frame of the attachment, this cam member being provided with a sinuous cam track within which is engaged a pin upon a lever connected with the feed plate. I

Attachments of this character comprise a considerable number of parts and for this reason the manufacture and asembly of the parts of the mechanism involves a considerable expense and it is, therefore, desirable to so construct the parts that they may be economically manufactured by quantity production methods and readily and easily assembled.

In the past the rotatable cam member referred to above has been manufactured from a solid piece of material, the material being cut away to form the sinuous cam track. According to the present construction this cam member is comprised of a pair of disks secured upon a hub, these disks being secured at opposite ends of the hub in spaced relation so that the cam track is formed between them, the metal of each disk being displaced or struck out transverse to the plane of the disk so as to provide alternate raised portions and valleys, thus forming a wavy or sinuous surface so that when the disks are secured to the hub in spaced relation as described, a sinuous cam track is provided.

These disks may be made by stamping operations and, therefore, manufactured very eco- 3 Claims. (Cl. 112-77) nomically. Moreover, as will be hereinafter explained, the two disks may be identical in form so that rights and lefts are not required, thus further lessening the cost of manufacture and assembly.

In sewing machine attachments of this character the actuating lever which is connected with the needle bar carries a pawl which is engaged with the teeth of a ratchet wheel secured upon the shaft of the cam member described above, and a spring is provided to maintain the pawl in engagement with the ratchet wheel. The present invention is also conucerned with the particular form and arrangement of this spring so that it may be cheaply made and easily secured in proper position in assembly of the device so that it will efiiciently maintain the pawl in its proper position and at the same time be very durable.

It is also usual in attachments of this kind to assemble the cam wheel with the associated parts of the frame so that there is suflicient friction to prevent backward movement of the cam and ratchet wheel in the normal operation of the device. In the present instance, however, I prefer to employ a holding member in the form of a spring secured to the base of the attachment and engaging the teeth of the ratchet wheel, the spring being a flat resilient member which, by its inherent resilience, may spring outwardly as the teeth of the ratchet wheel pass over its free end and then spring inwardly to engage back of one of the teeth so that the ratchet wheel may move only in a forward direction.

One object of the present invention is to provide a sewing machine attachment of the class described having a novel cam member by which the parts of the mechanism are actuated.

Another object of the invention is to provide a sewing machine attachment of the class described having a cooperating pawl and ratchet wheel with a novel form of'spring secured upon the lever which carries the pawl and engaged with the pawl and with the lever so as to efiiciently maintain the pawl in engagement with the teeth of the ratchet wheel.

Still another object of the invention is the provision of a novel form of holding pawl to prevent rearward movement of the ratchet wheel.

To these and other ends the invention consists in the novel features and combinations of parts to be hereinafter described and claimed.

In the accompanying drawings:

Fig. 1 is a side elevational view of a portion of a buttonhole attachment embodying myimprovements;

Fig. 2 is a top plan view of the parts shown in Fig. 1;,

Fig. 3 is a sectional view on line 3-3 of Fig. 1;

Fig. 4 is a detailed view of the pawl spring; and

Fig. 5 is a composite view of the cam showing the parts thereof in elevation.

The buttonhole attachment to which my improvements are applied as illustrated in the present application comprises a U-shaped frame It! to which is secured a base plate I I having disposed at its under side a pivoted feed blade l2 which, as will be understood from the reference to the Almquist Patent 2,482,607, is designed to be given a lateral oscillating or zig-zag motion with respect to the frame and base plate which are rigidly secured together.

Secured at the forward end of the U-shaped frame I0 is a so-called adapter l3 which is designed to be secured to the presser bar of the sewing machine in the usual manner. In order to impart lateral vibratory or zig-zag movementsto the feed blade 12, a lever I4 is pivoted at IE to the frame, which lever is operatively connected in a manner, not shown, to the feed blade. At its forward end, this lever carries anupwardly projecting pin extending into the cam track of a cam wheel designated generally at I8 and which will be described more particularly hereinafter.

This cam wheel is mounted upon a shaft I9 rotatably mounted in the spaced upstanding members of the U-shaped frame In, and upon a reduced end of this shaft which projects beyond the frame is rigidly secured a ratchet wheel 20.

Rotatably mounted on the shaft l9 between the ratchet wheel and the frame In is the usual fork arm 2| provided with a bifurcated free end 22 adapted to be connected with the needlebar so that the fork arm will be oscillated about the axis of the-shaft I9 upon reciprocation of the needle bar.

A pawl-23 is pivoted at 24 upon the fork arm 2|, the free end of the pawl engaging theteeth of'th'e ratchet wheel 20 so that as the fork arm is oscillated the ratchet wheel will be rotated in a step-.by-step movement in a forward direction, and, asqthe ratchet wheel is secured to the shaft I9, the latterwill also be rotated and will carry with it the cam |8 so that the latter will also .be given a step-by-step rotational movement in one direction.

In order to maintain the pawl in engagement with the teeth of the ratchet wheel 20, a U-shaped wire spring 25 is secured upon the fork arm 2| by having its bight portion clamped below the head of a rivet 26. The shorter leg. of this spring is provided with a laterally turned end 28 (Fig. 4) adapted to be received in an opening in the fork arm 2| so as to anchor this end against movement, while the longer arm of the spring is provided with a return bend 29 and a relatively long laterally extending end 30. The return bend 29 of the spring is adapted to overlie the back of the pawl 23 so as'to urge the end of the pawl toward the ratchet wheel 20, while the laterally extending end 30 is adapted to lie in a recess 3| in the upper edge of the fork arm and thus hold the spring in position.

In order to prevent rearward movement of the shaft l9 and associated parts during the reciprocation of the fork arm, a holding detent is provided to engage the teeth of the ratchet wheel so'thatithe latter will, not be permitted to move in a rearward or counter-clockwise direction as '4 shown in Fig. 1, with the downward movement of the forked arm. This detent is in the form of an L-shaped resilient member or spring 32, the base portion of which is secured to the base at 33. The upwardly'extending arm of the spring is provided with a laterally turned end 34 as shown in Fig. 3, which projects into the teeth of the ratchet wheel 20 and by engagement with the teeth holds the ratchet wheel against reverse movement. The spring 32 has sufficient resilience so that the teeth of the ratchet wheel will move it outwardly to permit the wheel to turn as shown in dotted lines in Fig. 1, and after passing a high point of one of the teeth of the wheel, the spring by its inherent resilience will again move into engagement with the rear face of the tooth.

The cam member |8 comprises three parts, as shown in Fig. 5, these parts comprising a hub and a pair of disks each of which is so shaped as to present a sinuous form adjacent its periphery. The hub 35 is provided with a threaded opening 36 so that it may be secured upon the shaft H) by the set screw 31 (Fig. 3). It is also provided with laterally projecting end portions 38 having flattened sides 39 thereon, and leaving shoulders 40 at the sides of the main portion 35 of the hub.

The disk members are identical in shape and a description of one will suffice for both thereof. Each of these disks is substantially circular in shape and provided with a non-circular opening 4| having a flat side 42 so that thi opening will receive one of the projections 38 to anchor the disk non-rotatably to the hub. After the disk has been pressed against the shoulder 40, as shown in Fig. 3, the metal of the member 38 may be spun over slightly to secure the disk in place. At spaced points adjacent its periphery the metal of each of the disks is struck or stamped outwardly as shown at 43 to provide a plurality of salient points or ridges and to provide between these ridges valleys 44 so as to give the edges of the disks a sinuous form.

As shown in Figs. 2 and 5, thedisks are assembled upon the hubmember in a back-to-back relation and theridges 43 are so located with respect to the flat portion 22 of the opening 4| that when so assembled one of the ribs 43 on one disk will lie opposite the valley 44 on the opposite disk. Thus, there is provided between these disks a sinuous cam track which, when the cam is rotated, will by engagement therein of the pin H impart a vibratory movement to the lever M.

It may be noted that in the manufacture of the cam disks, themetal of the disks is displaced through a distance greater than. that of the thickness of the disk so that the metal is actually cut through. This, however, can besuccessfully effected and two identicalfldisks thus made which, when placed backeto-back in spaced relation upon the. hub, will provide the sinuous track as illustrated.

.While I have shownand described a preferred embodiment of my invention, it will be understood that it is not to be limited to all of the details shown, but is capable of modification .and variationwithin the spirit of the invention and within the scope of the claims.

-What I claim is:

l In a sewing machine attachment having, a frame, a shiftable lever carried by the frame, means for eifecting lateral oscillatory movements of saidlever comprising a cam "rotatably mounted on the frame and operativel'yjcqnnected with said lever, a ratchet wheel secured to said cam, a fork arm pivoted on the frame, a pawl carried by the fork arm at one face thereof and engaged with the teeth of the ratchet wheel, and a spring secured to said fork arm to urge said pawl into engaging position, said spring being of U-shaped form and attached to the face of the fork arm at its b ight portion and having one leg secured to the arm and the other leg of the spring being provided with a return bend overlying the edge of the pawl and beyond said return bend a transverse end portion disposed in a notch in the upper edge of the fork arm.

2. In a sewing machine attachment having a frame, a shiftable lever carried by the frame, means for effecting lateral oscillatory movements of said lever comprising a cam rotatably mounted on the frame and operatively connected with said lever, a ratchet wheel, said cam comprising a hub separate from but fixed to a shaft to one end of which said ratchet wheel is rigidly attached outwardly of said frame and said fork arm, said hub having reduced non-circular end portions and a pair of sheet metal disks having non-circular openings received upon the end portions of the hub to be non-rotatably secured thereto, and said disks being of identical form and provided with spaced laterally displaced portions adjacent their edges and being disposed in reverse positions one with respect to the other upon the hub to provide between them a sinuous cam track.

3. In a sewing machine attachment, a frame having upstanding parallel side walls in one portion of its length, of laterally swingable lever having a portion positioned within the frame, a shaft journaled in openings in said walls, a hub between the side walls of the frame fixed to said shaft by a set screw and having reduced portions at the respective ends adjacent the side walls, sheet metal disks fixed to the reduced end portions of the hub and of identical form and provided with spaced laterally displaced portions adjacent their edges and being disposed in reversed positions one with respect to the other upon the hub to provide between them a sinuous cam track, and an upwardly projecting member carried by said swingable lever disposed in said cam track so that as the disks rotate the lever is oscillated.

ROBERT W. BURGESS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 163,738 Carney May 25, 1875 178,159 Jones May 30, 1876 549,539 Schoonmaker Nov. 12, 1895 2,207,293 I-Iinman July 9, 1940 2,374,721 Bacon et a1 May 1, 1945 FOREIGN PATENTS Number Country Date 14,357 Great Britain of 1886