US2303839A - Feeding mechanism for sewing machines - Google Patents

Description

Dec. 1, 1942. J. HQZA FEEDING MECHANISM FOR SEWING MACHINES Filed March 29, 1940 Patented Dec. 1, 1942 UNETED STATES PATENT OFFlCE FEEDING MECHANISM FOR SEWING MACHINES 3 Claims.

This invention relates to improvements in feeding mechanism for sewing machines of the type incorporating a four-motion feed dog, and has for an object to provide a simplified construction, the parts of which can be readily and inexpensively produced, and which renders possible precise adjustment of the amplitude of feeding movement in a simple manner.

As is understood, the movement of the usual feed dog comprises two components, namely, a risin and falling movement and a movement in horizontal direction, the second movement being adjustable to vary the stitch length. Heretofore it has been the practice to actuate the feed dog by means of two rock-shafts, namely, a feed rock-shaft and a feed-lift rock-shaft mounted beneath the sewing machin bedplate, said rockshafts deriving actuation from the main shaft, or one of said rock-shafts being driven from the loop-taker shaft.

In the feeding mechanism according to the invention, instead of the two relatively adjust able eccentrics which ar normally provided there is provided a single eccentric; i. e., the composite movement of the feed dog is derived from a single actuating eccentric, while the feature of adjustability of the feeding movement is retained.

The heretofore usual feeding mechanisms which employed eccentrics or slide lack the advantages of the construction according to the invention which employs a single eccentric and at the same time permits precise adjustment of the stitch length.

An embodiment of the invention is illustrated by way of example in the accompanying drawings in which Fig. 1 is a part elevation, part vertical section through the machine bedplate, Fig. 2 is a plan of the feeding mechanism and Figs 3 and 4 show in an end view and elevation view respectively, the adjustable eccentric for the feed dog.

On the rotary actuating shaft I mounted in bearings provided in lugs 2 depending from the machine bedplate there is keyed or otherwise secured an eccentric 3 on which are pivotally mounted levers 4 and 5 secured, against displacement axially of the shaft I by the collars 6.

On the stud I disposed parallel to said shaft and fixed in a lug Ia depending from the machine bedplate there is mounted a double-armed lever 9, the longer arcuate arm of which is provided with an arcuate guide groove 9' presenting a series of apertures Ill. The shorter arm of the lever 9 carries the pivot pin l I which passes through a sleeve-like bearing Ilia at one end of the feed bar I6.

The lever 4 is provided at its free end with a block I2 slidingly engaged in the groove 9' and adapted to be fixed in positionby a pintle I3 at one end of th double-armed lever I4 pivoted on the pin 15 fitted to a bifurcated lug provided on the lever 4. The pintle is urged into engagement with one or other of the apertures I0 by a spring 26 interposed between the lever 4 and the opposite end portion of the lever I4. The feed bar I6 provided with the feed dog Ill and articulated at one end to the pivot I I on the lever 9 is attached with its opposite end to an adjustable eccentric l8, I8a mounted in a bore of the lever 5 and adapted to be fixed in position by a set screw I9. By a manually rotative adjustment of the eccen.. trio IS the feed dog IT can be brought into the required horizontal position when the eccentric 3 has reached its highest position as illustrated in Fig. l.

Alteration of the stitch length is effected by varying the effective length of the lower arm of the lever B by withdrawing the pintle I3 from the aperture It engaged thereby and shifting the lever 4 angularly with the block I? in engagement with the groove 9 until the pintle I 3 is permitted to engage another aperture It. With the lever 4 in the position indicated at I there is realised a short stitch length; the nearer the free end of the lever 4 is brought to the pivot I the longer are the stitches formed.

It is to be understood that the invention is not limited to the particular construction described and illustrated.

I claim:

1. Feeding mechanism for sewing machines comprising an actuating shaft, an eccentric mounted on said shaft, a pair of levers joumalled on said eccentric, a double-armed lever having a stationary pivot between its ends parallel to said shaft, a feed bar articulated at one end to one lever of said pair of levers and articulated at its other end to one arm of said double-armed lever, and an adjustable connection between the other lever of said pair of levers and the other arm of said double-armed lever.

2. Feeding mechanism as claimed in claim 1, in which the second arm of the double-armed lever is formed with an arcuate groove, means on said second lever of said pair of levers for slidably engaging said groove, and a series of apertures in said second arm selectively engageable by a pintle on a manually operable adjusting lever mounted on the said second lever of said pair of levers.

3. Feeding mechanism as claimed in claim 1, including an adjustable eccentric pin pivotally connecting the first mentioned lever of the pair of levers with the feed bar, and means for locking said eccentric pin in a position in which said feed bar is horizontal provided the eccentric on said shaft has raised said first mentioned lever of said pair of levers to its highest position.

JOHN HOZA,

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