US3503354A - Link type thread take-up lever mechanism for a sewing machine - Google Patents

Description

March 31, 1970 YUTAKA T OMzlDA1 3,503,354

LINK TYPE THREADTAKE-UP L EVER MECHANISM FOR A SEWING MACHINE Filed 001;. 31, 1967 r 3 Sheets-Sheet 1 YUTAKA TOMIDA.

INVENTORS BYwwmmfii-L a4. PM; 01.111

March 31, 1970, YUTAKA TOMIDA 3,503,354

LINK TYPE THREAD TAKE-UP LEVER MECHANISM FOR A SEWING MACHIFNE Filed Oct. 31, 1967 3 Sheets-Sheet 2 FIG. 2A.

12 I' 1 60 14a II, 5

March 31, 1970 YUTAKA TOMIDA LINK TYPE THREAD TAKE-UP LEVER MECHANISM FOR A SEWING MACHINE 3 Sheets-Sheet 5 Filed Oct. 31, 1967 3 ANGLE OF ROTATlON OF ARM SHAFT POSITDN OF THREAD EYE IN THREAD TAKE UP LEVER YUTAKA TOMIDA INVENTORS BYQIMIMM ML QM. (1M3 United States Patent 3,503,354 LINK TYPE THREAD TAKE-UP LEVER MECHA- NISM FOR A SEWING MACHINE Yutaka Tomida, Kariya, Japan, assignor to Aisin Seiki Kabushiki Kaisha, Kariya, Aichi, Japan Filed Oct. 31, 1967, Ser. No. 679,353 Claims priority, application Japan, Nov. 4, 1966, 41/ 72,777 Int. Cl. Db 49/00 US. Cl. 112241 2 Claims ABSTRACT OF THE DISCLOSURE A thread take-up lever mechanism of the link type, in which a thread take-up lever support is oscillated through a stud by means of a cam securely mounted to an arm shaft, so that the movement of the thread take-up lever is improved, and the tension release of the upper thread is controlled substantially in proportion to the amount of the thread taken into the shuttle race of the sewing machine during the sewing operation, whereby the takeup lever functions substantially according to the theoretical value of the required slack of the thread, thereby always attaining an ideal sewing operation.

The principal object of the present invention, including the provision of an improved link-type thread take-up lever mechanism, which is adapted for high speed rotation of the arm shaft, is to provide an improved thread take-up lever mechanism, which is adapted for preventing any excess slackening of the upper thread, thereby enabling to effect ideal sewing operation.

Other objects of the present invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings wherein:

FIGURE 1 is a sectional elevation of a part of the arm of a sewing machine equipped with the thread take-up mechanism according to the present invention;

FIGURE 2 is a cross section taken along line 2-2 of FIGURE 1;

FIGURE 2A is an enlarged elevational view of the mechanism of FIGURE 1, as seen on line 2A2A thereof;

FIGURE 3 is a diagrammatic view, as seen from the face plate of the sewing machine, of the essential part of the mechanism to illustrate the manner ofoperation of the mechanism according to the present invention;

FIGURE 4 is a schematic view of the thread take-up lever, showing its manner of operation; and

FIGURE 5 is a diagram showing the amount of thread required by a shuttle race relative to the angle of rotation of the arm shaft of the sewing machine.

Referring to FIGS. 1, 2 and 2A, an armhead 1 is provided with an arm shaft 2 which is journalled in a front bearing 3. At one side of the arm shaft 2, namely the lefthand end of and in contact with said front bearing 3 as seen in FIG. 1, there is a thread take-up lever crank 4 fixed by means of a set screw 4a. A crank pin 5 is securely mounted to said crank 4 by means of a set screw 5a. One end 6a of the thread take-up lever 6 is pivoted to the crank 5, and the mid point 6b thereof is pivoted to a projection 7a of a thread take-up lever support 7. At the other end of the arm shaft 2, there is securely mounted thereto, by means of a screw 8a, a cam 8 for oscillating a take-up lever sup- 3,503,354 Patented Mar. 31, 1970 porting hinge stud. Connected to the cam 8 there is a crank rod 9, and the other end 9a thereof is pivotally connected to a take-up lever support arm 11 by means of a pin 10. Said oscillatable arm 11 is fixed to a rotatable stud 12 by means of a screw 11a. The stud 12 is journalled in a second bearing 13 on the armhead 1, and has a thread take-up lever support arm 14, and this support arm is provided with a supporting hinge stud 14a. 14b is a stop for limiting the axial movement of the take-up lever support 7. This support 7 has a hole 7b and a projection 7a, said hole 7b and the projection 7a being pivotably connected to the stud 14a and to the mid point 612 of the take-up lever 6, respectively. The crank pin 5 is secured to the crank 4 by means of the screw 5a; the crank 4 is secured to the shaft 2 by means of the screw 4a, and the cam 8 is secured to the shaft 2 by means of screw 8a, so that both of said crank pin 5 and cam 8 rotate in the same direction. According to the rotation of said cam 8, the crank rod 9 is reciprocated and, accordingly, the arm 11 will be oscillated through the pin 10. This oscillating motion is transmitted to the take-up lever support arm 14 through the stud 12, thereby producing oscillatory movement of the stud 14a thereon. On the other hand, the rotation of the crank pin 5 will turn the end 6a of the take-up lever 6, and simultaneously the mid point 6b of the take-up lever, being controlled by the movement of said projection 7a, will be reciprocated. It will be seen that the motion of the crank pin 5 is transmitted to the mid point 6b and the motion of the cam 8 is transmitted to the stud 14a of the take-up lever supporting arm 14, and that said two motions are combined by the projection 7a and the hole 7b of the take-up lever support 7, so that the thread eye 60 of the take-up lever 6 is moved according to said combined motion.

With reference to FIG. 3, 0 shows the angle of motion of the take-up lever supporting hinge stud 14a; F indicates the locus of the free end of said take-up lever support 7; G indicates the locus of the thread eye 60 of the take-up lever 6; and H indicates the locus of said take-up lever crank pin 5. In FIG. 4, I indicates the position of the thread take-up lever when the angle of rotation of the arm shaft 2 is K indicates the position of the take-up lever; and M indicates the position when the stud 14a is immovable as the conventional one.

According to the present invention, said take-up lever supporting hinge stud 14a is made oscillatable and so arranged that the dead point of its oscillating movement is so determined that the speed of movement of the takeup lever 6 is adjusted to conform with the amount of the thread required in the shuttle race, and that the phase angle of the take-up lever crank pin 5 and the earn 8 may be adjusted.

The operation of this invention is as follows: Assuming that the cam 8 and the crank pin 5 are arranged as shown in the drawing relative to the arm shaft 2 and rotated in the direction of arrow, the rotation of the cam 8 in the direction of a b 0 and d will be transmitted to the crank rod 9 and, through the pin 10, will produce the oscillating movement of the oscillatable arm 11. Said oscillating movement will be transmitted to the take-up lever supporting arm 14 through the stud 12, thereby producing the oscillating movement of the supporting hinge stud 14a thereof for the same angle. The crank pin 5 will rotate in the direction of a b 0 and d turning the end 6a of the take-up lever, and the midpoint 6b thereof takes a reciprocating movement thereby. At this time, the movement of the cam 8 will produce the oscillating movement of the take-up lever supporting hinge stud 14a, said movement being transmitted to the projection 7a of the take-up lever 6, and the projection 7a of the take-up lever support 7 will take the movement combined with that is the midpoint 6b described by the locus of a, b, c', and d in FIG. 3. Said movement Will result in the movement of the thread eye 6c of the take-up lever 6 described by the locus of A, B, C and D.

As the crank pin and the cam 8 are in the phase relation as shown in FIG. 3, when the take-up lever supporting hinge stud 14a is in the position b", the projection 7a of the take-up lever support 7 will take the position b. Similarly, the position of said projection 7a corresponding to the mid points a, c" during the oscillation will be at a c, and the position of said stud 14a corresponding to said projection 7a will be at d.

When the supporting projection 7a is given the motion along the locus of a, b, c and d in the above manner, the thread eye 60 of the take-up lever during its movement from A to B- will result in decrease of amount of descending movement, so that the effect of slackening of the thread (amount of supply of the upper thread) will be decreased, and said decreasing effect will be marked the highest at the point B. When the thread eye 60 moves to C-D, increasing the amount of descending movement, it will rapidly effect increased slackening of the upper thread being supplied. When the thread eye 6c moves from D to A, the upper thread is released from the shuttle race, and the thread eye 60 is rapidly lifted, so that the slack of the upper thread is rapidly absorbed. From the foregoing, it will be seen that the movement of the thread eye 60 of the take-up lever can be controlled so as to conform with the amount of the upper thread required by the shuttle race, by giving the oscillating move ment a", b, c" and d" to the supporting hinge stud 14a of the take-up lever.

FIG. 5 shows the amount of the upper thread required in the shuttle race relative to the angle of rotation of the arm shaft based on the upper dead point of the needle bar of the sewing machine. In this figure, X indicates the amount of the upper thread required in the shuttle race; Y indicates the amount of the upper thread required by the action of the link type thread take-up lever according to the present invention; and Z indicates the amount of the upper thread required by the action of a conventional thread take-up lever of the link type.

The process of the motion of the thread take-up lever being rather complicated, the explanation thereof will be made as divided into following five parts and based on the angle of rotation of the arm shaft:

(1) Beginning with the highest position of the take-up lever and ending with the position of the needle penetrated the fabric;

(2) Beginning with the lower position of the needle, and ending with its position where the seizing beak of the shuttle race seizes the loop of the thread;

(3) Beginning with the rotation of the shuttle race with its beak seizing the loop of the upper thread and just starting releasing thereof;

(4) Beginning with the shuttle race releasing the upper thread and ending with the take-up lever starting the slackening of the upper thread;

(5) Ending with the take-up lever positioned near the highest position and completing the formation of the seam in co-operation with the tension spring.

In FIGS. 5, A, B, C and D indicate the amount of the upper thread being supplied at respective positions of the thread eye 60.

Near the end of the period (1), the needle penetrates the fabric. At this stage, a slight slack of the thread would be necessary, for if otherwise there might occur a breaking of the thread, and the amount of slack Z is provided.

During the period (2), the needle penetrating the fabric descends, thereby necessitating the amount of the thread twice the amount of movement of the needle, there producing required slack of the thread at the upper surface of the fabric. At this time, according to the present invention, the thread take-up lever 6 will start its function to decrease the amount of its descending movement so as to decrease the amount of slack of the thread, compensating for the necessary amount of slack of the thread. indicates the reduced amount of slack of the thread as decreased according to the present invention.

During the period (3), the beak of the rotating shuttle race seizes the loop of the upper thread and increases taking-in amount of the thread up to the highest amount.

Amount of descending move-ment of the take-up lever being larger, there appears larger slack of the thread above the upper surface of the fabric. Moreover, in the conventional mechanism, the highest amount of slack of the upper thread occurs near the point C, so that the upper thread would be subjected to excessive slack.

The amount of slack according to this invention will be 1 at the point C, which is smaller by 5 than the amount obtainable in the conventional mechanism.

According to this invention, the action for increasing the slack of the upper thread will become the highest at the point D, and there remains the necessary and sufficient amount of slack 1 Thus the thread cutting will be prevented.

During the period of (4), the upper thread is not restricted by the action of the shuttle race, and the thread take-up lever rapidly absorbs the slack of the upper thread.

The period of (5) is short, and the take-up lever is at its upper dead point, similarly as in the conventional mechanism.

From the foregoing, according to the present invention, it will be understood that the thread take-up lever operates to supply the upper thread in such manner that any excess slack of the thread is prevented by limiting the amount of the thread in conformity with the necessary amount of the thread required by the shuttle race, so that it is able to readily form the desired beautiful seam. It is also able to avoid any difficulty in effecting any adjustment of the mechanism. The mechanism is adapted also for any thread having less tension as well as for any soft twist thread.

What I claim is:

1. Thread take-up lever mechanism of the link type for a sewing machine, wherein there is provided an armhead, an arm shaft having an inner and outer side on said armhead, a front bearing journalled on said arm shaft, a cam securely mounted on said arm shaft, said cam being arranged at the axially inner side of said front bearing, a take-up lever crank fixed on said arm shaft at the axially outer side thereof, a crank pin mounted on said take-up lever crank, a rotatable stud parallel to said arm shaft, having a projection, said stud being mounted on a second bearing on said armhead, and said projection having a take-up lever support arm to which a take-up lever support is pivoted, an operative connecting means between said cam and stud, a thread take-up lever pivoted to said take-up lever support, whereby oscillatory movement is transmitted from the cam to the take-up lever support arm through the operative connecting means and the stud, and to the take-up lever support through the take-up lever support arm, and the take-up lever being simultaneously controlled by the take-up lever support and is reciprocated by means of said crank pin in conformity with the amount of the thread required in the shuttle race of the sewing machine.

2. Thread take-up lever mechanism of link type as defined in claim 1 wherein the operative connecting means includes a crank rod and a further thread take-up lever support arm being pivoted to each other at the one end,

while at the other end, respectively, the former being 3 5 6 operatively connected to the said cam and the latter se- FOREIGN PATENTS cured to the stud.

, 466,293 10/1951 Italy.

References Clted 671,657 2/1939 Germany.

UNITED STATES PATENTS 1 402 930 1 1922 112 5 MERVIN STEIN, Primary Examiner 3,025,810 3/1962 Ebihara et a1. 112241 G. H. KRIZMANICH, Assistant Examiner

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