US2704987A - Mechanism for actuating the needle bar and thread puller in a sewing machine - Google Patents

Description

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O m R J COURT ET AL MECHANISM FOR ACTUATING THE NEEDLE BAR Filed Nov. 27, 1951 March 29, I955 AND'THREAD FULLER IN A SEWING MACHINE United States Patent MECHANISM FOR ACTUATm G THE NEEDLE BAR AND THREAD PULLER IN A SEWING MACHINE Jean Court, Chatelaine-Geneva, and Ramon Casas Robert,

Geneva, Switzerland, assignors to Mefina S. A., Binnmgen, Switzerland, a corporation of Switzerland Application November 27, 1951, Serial No. 258,332 Claims priority, application Switzerland January 22, 1951 Claims. (Cl. 112241) This invention relates to sewing machines and more particularly has reference to a mechanism for actuating the needle bar and thread take up.

The actuating mechanism for the to and fro or reciprocating movement of the needle bar and thread take up of a sewing machine usually comprises a horizontal shaft arranged in the arm of the sewing machine and carrying a crank to which is connected one end of a connecting rod having its other end connected to the needle bar. The thread take up, when it is of the articulated type, is driven by a crank pin usually carried by the crank which actuates the needle bar.

To obtain the necessary time lag or interval between the movements of the needle bar and the thread take up, the crank pin actuating the latter is angularly displaced relatively to the crank pin actuating the needle bar.

In one type of prior art needle bar and articulated thread take up actuating mechanism for sewing machines, the horizontal crank pin carrying shaft and the reciprocable vertical needle bar are located in the same plane and the main crank pin has one end of the needle bar connecting rod connected directly thereto. The crank pin also has fixed thereto a plate which in turn carries a thread take up actuating crank pin, the axis of which is angularly displaced from the axis of the main crank pin about the axis of said shaft to provide for the required lag or interval between the operation of the needle bar and the thread take up necessary to enable the thread take up to continue delivery of thread to the needle and the shuttle after the needle has been withdrawn from the material being sewn.

One disadvantage of such type of mechanism is that the crank carrying the two crank pins and the plate fixed on the main crank pin and carrying the thread take up actuating crank pin are of complicated and delicate construction which renders the mechanism expensive.

In other types of prior art needle bar and articulated thread take up actuating mechanisms for sewing machines a single crank pin or two crank pins having a common axis are carried by the horizontal shaft for reciprocating the needle bar and actuating the thread take up.

Since in these machines the movements of the needle bar and of the thread take up are not relatively displaced in order that a certain length of thread may still be delivered to the shuttle after the needle has been withdrawn from the material to be sewn, it is necessary to have the thread slide over a guide placed in its path between the eye of the thread take up and the needle.

This guide is thus an additional element and expensive to provide. Furthermore, it is a cause of friction and wear of the thread between the feed bobbin and the nleedlg, which may lead in some cases to breakage of the t rea On the other hand, it should be noted that in the above mentioned prior constructions, the geometric axis of the horizontal shaft actuating the needle bar and the thread take up and the geometric axis of the needle bar itself, are arranged in one and the same plane.

An object of the present invention is to provide a mechanism for actuating a needle bar and a thread take up of a sewing machine which avoids the disadvantages of the prior art mechanisms.

Another object of this invention is to provide a mechanism for actuating a needle bar and a thread take up of a sewing machine, in which the connecting rod for reciprocating the needle bar is pivotally connected to a crank pin carried by a horizontal shaft, and the thread 2,704,987 Patented Mar. 29, 1955 take up is pivotally connected to a crank pin carried by said horizontal shaft, the two crank pins having the same axis and in which the needle bar is disposed a distance from the vertical plane passing through the axis of said horizontal shaft carrying the crank pins sutflcient to produce a time lag or interval between the movements of the needle bar and the thread take up.

Other objects will appear in the following description and drawings.

To facilitate the understanding of the present invention regerfince is made to the accompanying drawings in w 10 Fig. 1 is a diagrammatic end elevation view of a needle bar and thread take up actuator of a known type.

Fig. 2 is a side elevational view of a portion of the mechanism shown in Fig. 1.

Fig. 3 is an end elevation of the head of a sewing machine with parts removed to show the drive mechanism for the needle bar and thread take up constructed according to the present invention.

Fig. 4 is a detailed fragmentary view in front elevation of the mechanism for actuating the needle bar and thread take up.

Fig. 5 is a view similar to that of Fig. 4 showing a modified form of structure.

In the device of known type shown in Figs. 1 and 2, the needle bar 1 and the horizontal shaft 2 are located in the same plane. The shaft 2 carries the crank 3, the crank pin 4 of which actuates the needle bar 1 through a connecting rod 5.

The thread take up 6 is of the articulated type. An arm 7 pivoted on a fixed pin 8 in the machine is connected at 9 to the middle portion of the thread take up 6. The foot of the latter is joined to a crank pin 10 carried by the crank 3, and in the present case, by the crank pin 4, one end of which is fixed to a small plate 11 on which is mounted the crank pin 10.

The angular displacement between the two crank pins 4 and 10 operates to retard the movement of the thread take up 6 relative to the movement of the needle bar 1 which is necessary so that the thread take up can continue to deliver thread to the shuttle after the needle has been withdrawn from the work material.

As illustrated in the drawings Figs. 3 to 5 the mechanisms according to the present invention for imparting vertical reciprocating movement to the needle bar 1 and the articulated thread take up 6 comprise a horizontal shaft 2 mounted in the arm 12 of the sewing machine for rotation and carrying a crank. In the illustrated construction the crank is in the form of a fly wheel 13 on which is fixed a crank pin 4 for reciprocating the needle bar 1 through the intermediary of the connecting rod 5.

Thread take up 6 is of the articulated type and has its foot or lower end formed as a fork provided with two tines 6a. Each tine is provided with a bore to receive the crank pin 4 so that the forked end of the thread take up can be mounted on the crank pin 4 with the tines 6a disposed on opposite sides of the connecting rod 4 as clearly shown in Fig. 4.

The thread take up 6 is connected intermediate its forked end and its free or thread receiving end by a pivot 9 on the free end of an arm or link 7. At its other end link 7 is mounted for rocking or pivotal movement about a pivot 8 carried by a fixed part of the head of the sewing machine.

In the illustrated construction, this fixed part of the machine is a block 14, attached by screw 15 to the machine frame. Since the illustrated sewing machine is adapted to elfect zigzag stitching, as described in application Serial No. 84,608, filed March 31, 1949, now Patent No. 2,682,845, dated July 6, 1954, the needle bar 1 is reciprocably mounted in a rocker 16 capable of rocking about a shaft 17 fixed in a support block 18 attached by means of a screw 19 to the machine frame. The upper end of the shaft 17 is reciprocably mounted in the block 14. By loosening the screw 19 it is possible to shift the supporting block 18 transversely of the arm of the machine, which operation is facilitated by an eccentric device 20. The transverse shifting of the supporting block 18 produces an angular displacement of the shaft 17 and the block 18 about the axis of the screw 15.

The needle bar 1 also participates in the angular movement whereby it is possible to regulate the position of the needle in a plane transverse to the arm of the machine.

To prevent the oscillating movement of the needle bar 1 about the shaft 17 being transmitted to the connecting rod when the machine is effecting sewing in zigzag or other ornamental fashion, the connecting rod 5 has a nose 21 with a slot 22 therein which enables the rod to follow a guide 23 formed by the edge of a plate 24 fixed to the machine frame.

As shown in Figure 4, the pivot 9 includes a stub pin 25 fixed in the middle portion of the thread puller 6 and the arm 7 is mounted thereon with the interposition o a porous metal sleeve 26 containing a lubricant. In this manner this joint does not require periodic lubrication.

In the mechanism described, to permit the necessary time lag between the movements of the needle bar 1 and the thread take up 6, the needle bar 1 is positioned at a sufiicient horizontal distance from the vertical plane passing through the geometric axis of the horizontal shaft 2.

Thus the needle reaches its lowest point at the instant when the axis of the crank pin 4 is in the plane passing through the geometric axis of the shaft 2 and the axis of the pin 5a connecting the connecting rod 5 to the needle bar 1, and between these two axes.

In this position, which is that shown in Figure 3, the crank pin 4 has not reached its lower dead point nor has the foot of the thread take up.

The latter will not attain its lowest point until the crank pin 4 occupies the position 4' shown in dotted lines in Figure 3, that is to say, until the crank pin 4 will lie in the vertical plane passing through the horizontal shaft 2. Such an arrangement of the needle bar 1 relatively to the shaft 2 produces an effective shift between the movements of the needle bar 1 and the thread take up 6 notwithstanding that the connecting rod 5 and the foot of the thread take up 6 are connected on the same crank pin 4. The path T of the eye of the thread take up 6 is shown in dotted lines in Figure 3 and it will be seen that this path is particularly favorable since it has no substantially lateral displacements and its general direction is inclined to the axis of the needle.

Figure 5 shows a modification of the actuating mechanism and particularly with respect to the connection of the connecting rod 5 and lower end of thread take up 6 to the pin carried by the crank 3. In this modification the crank pin on which the connecting rod 5 is pivoted is in the form of a sleeve 4a carried by the flywheel 13. The connecting rod 5 is provided with a bore for receiving the sleeve 4a as shown. A pin 27 is carried by the foot of the thread take up 6, and this pin projects through the bore of the sleeve 40. An elastic washer 28 engages in a groove 29 on the end of the pin 27 and serves to retain the pin within the sleeve 4a. This retains the thread take up in place and in turn the lower portion of the thread take up retains the connecting rod in place on the sleeve 40 between the flywheel 13 and the thread take up.

It should be noted furthermore that in the case of application of the present driving mechanism to a machine of the type capable of making zigzag and other ornamental stitching with a free arm and with a shuttle rotatably mounted on an axis substantially vertical, the arrangement of the horizontal shaft 2 and the needle bar 1 within spaced vertical planes permits the upper arm of the machine to be located directly above the free lower arm.

Furthermore since the horizontal shaft 2 is in this case displaced laterally in the upper arm, sufiicient space is left in the latter to install a lamp without it being necessary to provide on the said arm a bulge for this purpose. For this reason, the general appearance of the machine is rendered more attractive.

From the foregoing, it will be realized that the mechanism of the present invention combines the advantages of each of the two known mechanisms previously described, that is to say, the use of a crank with a single crank pin actuating both the needle bar and the thread take up. This arrangement eliminates, by reason of the displacement of the two vertical planes, one containing the geometric axis of the drive shaft and the other the geometric axis of the needle bar, the disadvantages of the said prior constructions and par icularly of the supplementary guide of the thread between the eye of the thread take up and the needle.

Having described our invention we claim:

1. A sewing machine comprising a head, a needle bar mounted in the head for vertical reciprocating movement, a horizontal rotary shaft mounted in the head, a crank carried by said shaft, a connecting rod pivotally connected at one end to said needle bar and having its other end pivotally connected to said crank at a distance from the axis of said shaft, a crank pin carried by said shaft, and an elongated articulated thread take up having one of its ends pivotally mounted on said crank pin, and its other thread-engaging end free, a link pivotally connected at one end to said head and pivotally connected at its other end to the thread take up between its ends to impart reciprocating movement to the free end of the thread take up in a substantially vertical path, the axis of the pivotal connection of the connecting rod to the crank coinciding with the axis of the crank pin, said needle bar being spaced horizontally from a vertical plane passing through the axis of the horizontal shaft 21 sufiicient distance to provide a lag between the operation of the needle bar and the thread take up so that the downward movement of the take up lags behind the downward movement of the needle bar.

2. A sewing machine according to claim 1 in which the end of the thread take up connected to the crank pin is in the form of a fork with two tines and the end of the connecting rod connected to the crank is disposed between said tines.

3. A sewing machine comprising a head, a needle bar mounted in the head for vertical reciprocating movement, a horizontal rotary shaft mounted in the head, a tubular crank pin carried by said shaft with its axis eccentric with respect to the axis of the shaft, a connecting rod pivotally connected at one end to said needle bar and having its other end provided with a bore for receiving said crank pin to pivotally connect it to said crank pin for pivotal movement about the axis of said crank pin, an elongated articulated thread take up having a thread engaging free end, and a stud pin carried at the other end of said thread take up and extending within the tubular crank pin to pivotally connect said end of the thread take up to said crank pin for pivotal movement about the axis of said crank pin, a link pivotally connected at one end to said head and pivotally connected at its other end to the thread take up between its ends to impart reciprocating movement to the free end of the thread take up in a substantially vertical path, the axis of the pivotal connection of the connecting rod to the crank coinciding with the axis of the crank pin, said needle bar being spaced horizontally from a vertical plane passing through the axis of the horizontal shaft a suflicient distance to provide a lag between the operation of the needle bar and the thread take up so that the downward movement of the take up lags behind the downward movement of the needle 4. A sewing machine comprising a head, a needle bar mounted in the head for vertical reciprocating movement, a horizontal rotary shaft mounted in the head, a tubular crank pin carried by said shaft with its axis eccentric with respect to the axis of the shaft, a connecting rod pivotally connected at one end to said needle bar and having its other end provided with a bore for receiving said crank pin to pivotally connect it to said crank pin for pivotal movement about the axis of said crank pin, an elongated articulated thread take up having a thread engaging free end, and a stub pin carried at the other end of said thread take up and extending within the tubular crank pin to pivotally connect said end of the thread take up to said crank pin for pivotal movement about the axis of said crank pin, a link pivotally connected at one end to said head and pivotally connected at its other end to the thread take up between its ends to impart reciprocating movement to the free end of the thread take up in a substantially vertical path, the axis of the pivotal connection of the connecting rod to the crank coinciding with the axis of the crank pin, said needle bar being spaced horizontally from a vertical plane passing through the axis of the horizontal shaft a sufficient distance to pro vide a lag between the operation of the needle bar and the thread take up so that the downward movement of the take up lags behind the downward movement of the needle bar, said stub pin being fixed at one of its ends to said thread take up, and means on the other end of said stub pin to retain it within the crank pin with the connecting rod interposed between the thread take up and the portion of the horizontal shaft carrying the crank pin.

5. A sewing machine comprising a head, a needle bar mounted in the head for vertical reciprocating movement, a horizontal rotary shaft mounted in the head, a tubular crank pin carried by said shaft with its axis eccentric with respect to the axis of the shaft, a connecting rod pivotally connected at one end to said needle bar and having its other end provided with a bore for receiving said crank pin to pivotally connect it to said crank pin for pivotal movement about the axis of said crank pin, an elongated articulated thread take up having a thread engaging free end, and a stub pin carried at the other end of said thread take up and extending within the tubular crank pin to pivotally connect said end of the thread take up to said crank pin for pivotal movement about the axis of said crank pin, a link pivotally connected at one end to said head and pivotally connected at its other end to the thread take up between its ends to impart reciprocating movement to the free end of the thread take up in a substantially vertical path, the axis of the pivotal connection of the connecting rod to the crank coinciding with the axis of the crank pin, said needle bar being spaced horizontally from a vertical plane passing through the axis of the horizontal shaft a suflicient distance to provide a lag between the operation of the needle bar and the thread take up so that the downward movement of the take up lags behind the downward movement of the needle bar, said stub pin being fixed at one of its ends to said thread take up, and provided with a groove in its circumferential surface at the other end thereof, and a resilient washer mounted in said groove to retain the stub pin within the crank pin with the connecting rod interposed between the thread take up and the portion of the horizontal shaft carrying the crank pin.

References Cited in the file of this patent UNITED STATES PATENTS 842,161 Ammerman Jan. 29, 1907 946,019 Diehl Jan. 11, 1910 20 2,173,320 De Voe Sept. 19, 1939 FOREIGN PATENTS 139,866 Great Britain July 14, 1920

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