US2868150A

US2868150A - Means for adjusting the stroke of the feed dog in sewing-machines

Info

Publication number: US2868150A
Application number: US625399A
Authority: US
Inventors: Moro Antonio
Original assignee: Borletti SpA
Current assignee: Borletti SpA
Priority date: 1955-12-20
Filing date: 1956-11-30
Publication date: 1959-01-13
Anticipated expiration: 1976-01-13
Also published as: BE552743A; DE1087436B; FR1165951A

Description

Jan. 13, 1959 MORO 2,868,150

MEANS FOR ADJUSTING THE STROKE OF THE FEED DOG IN SEWING-MACHINES Filed Nov. :50, 1956 FIG. 2

In ventor ANTON/0 Mo/eo y W247i A torn e y United States Patent T MEANS FORADJUSTING- THE STROKE'OF THE FEED DOG IN SEWING-MACHINES Antonio Moro, Milan, ltaly assignor to S; p. A.

Fratelli Borletti, Milan, Italy "Applicafioll'Nbv embel' 30, 1956 Se'nal' 'No. 625,399 Claims priority, application Italy December 20, 1955 Claims. (Cl. 112-210) In sewing machines, particularly ofthe domestic kind, themechanism for adjusting the displacing amplitude or stroke of the cloth-pushing feed dog is actuated by a lever, on the angular deviation of which, either in one or in the opposite direction" withrespect to a zero position, depends the amplitude of the feed dog displacing either forwards or backwards and thus the stitch length of the seam effected in the corresponding direction.

The present invention relatesto a device for stopping said actuating lever in any chosen position, that is to a device making it possible to establish the feed dog displacing amplitude each time in any desired manner, and'keeping said amplitude equal for both the forward and the backward displacing; said device differs from already known devices of the same kind due to a particular structure adapted to give it a wide possibility of varying the stop-position, assuring, at the same time, by simple means, a speedy and safe operation.

This device is characterized in that two double-armed levers, mounted on two pivots respectively placed on either side of the pivot of the actuating lever of the adjusting mechanism, are so combined with two cams mounted the one over the other, with different orientation on a common pivot, that said cams, placed between two corresponding arms of said levers, held by springs adherent to the cams, impart by their rotation in either direction a movement for opening or shutting respectively said levers like scissors said levers serving by means of their other two arms as stops for a pivot carried by the actuating lever of the adjusting mechanism.

By such a disposition the distance of the stop position from a zero position for the actuating lever of the adjusting mechanism deviated in either direction is always the same, so that for each position of the device according to the invention the forward displacing amplitude of the cloth pushing feed dog is equal to the backward displacing of said feed dog, the stitch length thus resulting equal for both the. forward and the backward seams as it must in fact be when a normal sewing-work is effected.

According to a further characteristic of the invention, the spring, by means of which the lever for determining the forward displacing of the cloth-pushing feed dog is held adherent to the corresponding driving cam, is disposed in such a manner as to always hold said lever approached to the stop of the actuating lever of the adjusting mechanism, the latter lever being thus always carried along by said former lever, in its movement.

Therefore the only driving of the stop device according to the invention is sufficient for producing, at the same time, the driving of forward seam of the adjusting mechanism, thus greatly simplifying the relative handling.

In the machines of a domestic kind this is very useful, as by these machines only the forward seam must be generally performed, the backward seam being required only for a few closing stitches after the forward seam has been effected. For these closing stitches it is sufficient to push backwards the actuating lever of 'theadjusting mechanism against the action of the mentioned spring, which then carries forward said lever again, as soon as the latter is set free.

The object of the present invention is illustrated by an embodiment in the annexed drawing, in which Fig. 1 shows in front view the device in a zero position, that is in the position not displacing the feed dog;

Fig. 2 is a cross section ofthe device according to lines A-B of Fig. 1;

Fig. 3 is a front view of the device shown in position for a maximum stitch length;

Fig. 4 shows a modification of the driving means for the actuating lever of the adjusting mechanism.

With reference to Figs. 1 to 3, pin 1, preferably eccentric for the phase adjusting, is fixed on bell crank lever 2 actuating the mechanism for adjusting the dis placement of the cloth-feeding dog, that is to the lever, the position of which through a mechanism shown in More British Patent No. 788,081, controls the pitch and the displacing direction. of the feed dog transporting the cloth. It will be understood that the apparatus of the present invention replaces the feed dog operating mechanism shown in Fig. 10 of the aforesaid British patent. Lever 2 is fixed on pivot 3 adapted to rotate in hole 4 of bearing 5 fixed to the machine frame. Externally to hearing 5, handle 6 for shifting lever 2 is fixed on pivot 3.' Pin 1 is restrained in its displacings about the axis of pivot 3 by the two arms 7 and 8 of the two levers 9 and 10, respectively pivoted at 11 and 12.

The other two arms 13 and 14 of levers 9 and 10 have the respective surfaces 15 and 16 always in contact with the peripheral surfaces 17 and 18 respectively, of two cams 19 and 20 similar to each other but having different orientation, said cams being mounted on shaft 21 rotated from the outside by knob 22. These cams can be relatively displaceable between each other for the phase adjusting,,and can be fixed on shaft 21 after the displacing.

Pin 1 of lever 2 is always held against arm 7 by spring 23, which keeps the cam-engaging surface 15 on cam 17. Cam-engaging surface 16 of arm 14 is always held in engagement with cam 18 by a spring 24.

When knob 22 is turned, cams 19 and 20 rotate, so that the distances 25 and 26 from the rotation axis 21 of the contact points between the cam-engaging surfaces 15 and 16 and the surfaces of the respective cams 17 and 18 vary and consequently levers 9 and 1t) rotate about the respective pivots 11 and 12. Pin 1, and thus lever 2, follows lever 9 in its displacement, while lever 8 is symmetrically displaced of the same angle as lever 9, with respect to the central zero position (AB). In any of these positions, the machine will sew forward with a pitch corresponding to the position, for instance :27, taken up by pin 1, said position being in its turn 'determined by the angular position of cam 19.

By turning handle 6 according to arrow 28 till pin 1 is stopped against lever 8, in its new position 27, the machine will sew backward with a stitch length equal to the one of the forward seam; by leaving handle 6 free, all will return as before on account of spring 23, and thus for any other position of earns 19 and 20, as surfaces 17 and 18 of said cams are, as already said, shaped so that both arms 7 and 8 of levers 9 and 10 are simultaneously displaced of angular values equal between each other with respect to the origin (AB).

In order to regulate the stitch length according to determined values, knob 22 is provided with a graduation 29 adapted to be read in correspondence of the fixed index 39, the graduation values, for instance, can cor- 3 respond to millimeters of the feed dog displacement for each stitch.

Fig. 3 shows cams l9 and 20 and, respectively lever, 7 and 8 in position of a maximum opening corresponding to the maximum stitch length: lever 2 can be brought, according to arrow 28, from where pin 1 is in position 31 to where it is in position 32, thus preparing the feed dog for the maximum forward and, respectively, backward stroke.

In the modified embodiment shown in Fig. 4, lever 2 carries another arm 2 connected through tie rod 33 to end 34 of a lever pivoted at 35 and being remote from lever 2; the rotation of lever 2 is effected by actuating lever 36, all the remainder working as previously described.

It is well understood that the particulars of construction of the device can vary from those represented in the drawing and above described, said device always remaining within the frame of the invention.

What I claim is:

1. Mechanism for controlling the setting of a feed dog control lever comprising a feed dog control lever, said lever having a pin on one arm thereof, a shaft rotatably mounting said lever, second and third shafts disposed on opposite sides of said first shaft, a pair of displacement control levers mounted on said second and third shafts and having cam follower surfaces on the lower arms thereof and engagement surfaces for said pin on the upper arms thereof, and adjustable cam means contacting said cam follower surfaces to vary the positions of said displacement control levers and thereby control the range of movement of said pin and feed dog control lever.

2. The mechanism of claim 1, said adjustable cam means comprising a pair of cam plates mounted on a common shaft, and means to turn said shaft to vary the setting of said cams.

3. The mechanism of claim 1, and spring means urging said cam follower surfaces into engagement with said cam means.

4. The mechanism of claim 1, and further including spring means urging said pin into engagement with one of said engagement surfaces of one of said displacement control levers.

5. The mechanism of claim 4, and further including means to rotate said feed dog control lever against the urging of said spring to engage said pin with the other engagement surface of the other displacement control lever.

References Cited in the file of this patent UNITED STATES PATENTS 2,679,220 Biesemeyer et a1 May 25, 1954 2,704,986 Pagni Mar. 29, 1955 FOREIGN PATENTS 314,696 Great Britain July 4, 1929 360,910 Italy July 8, 1938