JPH07108355B2 - Needle thread swing prevention mechanism - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention prevents an upper thread that forms a loop below a sewing object by a vertical movement of a balance from swinging when a rotary hook captures it. The present invention relates to a needle thread swinging prevention mechanism.

[Prior Art] An upper thread that forms a loop below a sewing object due to vertical movement of a balance is hung on a sword tip of a rotary hook, and passes through the rotary hook to cross a lower thread to form a stitch. But
When the needle thread swings above the sewn item due to, for example, the vertical movement of the sewing needle, the loop formed below the sewn item also sways, and the stitch is not formed on the rotary hook hook and no stitch is formed. Inconvenience occurs.

In order to eliminate such inconvenience, a rocking prevention mechanism has been proposed which holds the needle thread between the balance and the sewing needle to prevent the needle thread from rocking.

FIG. 3 is a view showing such a conventional rocking prevention mechanism. In the swing prevention mechanism shown in FIG. 3A, 2a is a first plate body fixed between the balance of the sewing machine main body and the sewing needle, and 2b is a second plate provided so as to face the first plate body 2a. It is a plate.

Reference numeral 3 denotes a screw body that penetrates the second plate body 2b and has its tip screwed into the first plate body 2a.

And, 4 is engaged with the screw body 3 at one end and the second plate body 2b at the other end.
The second plate body 2b is urged against the first plate body 2a.

If the needle thread 1 is inserted between the plate bodies 2a and 2b of the rocking preventive mechanism having the above structure as shown in the figure, the rocking preventive mechanism presses the needle thread 1 by the biasing force of the spring 4, 1 can be prevented from swinging.

Further, the pressing pressure on the upper thread 1 can be adjusted by advancing and retracting the screw body 3.

On the other hand, the rocking preventive mechanism 5 shown in FIG. 3B is made of a U-shaped rubber material or the like and is fixed to the sewing machine main body between the balance and the sewing needle so that the needle thread 1 is sandwiched as shown in the figure. The upper thread 1 can be pressed and prevented from swinging.

[Problems to be Solved by the Invention] However, the conventional techniques have the following problems.

The rocking preventive mechanisms shown in FIGS. 3 (a) and 3 (b) hold the upper thread up and down when the upper thread is being fed by the vertical movement of the balance and when the upper thread is tightened. Therefore, the upper thread that forms the loop is untwisted under the sewing object, and there is a problem that the blade point of the rotary hook cannot properly capture the upper thread.

Particularly, in a two-needle sewing machine, when the upper thread is fed by the cloth feeding action, this phenomenon is remarkable due to the ironing of the needle hole of the needle with respect to the thread on the left side. That is, when the twist of the upper thread returns, a large number of fiber threads are exposed to the upper thread, and the sword tip of the rotary hook captures only a part of these fiber threads to form a seam. There are hanging stitches,
This causes inconvenience such as the rotary hook cutting a part of the fiber yarn.

Further, since each of these rocking preventing mechanisms is always slid on the upper thread, the upper thread is significantly worn, and frequent replacement is required, so that the work efficiency is low.

[Means for Solving Problems] Therefore, the present invention is a sewing machine that forms a stitch by cooperation of a balance, a sewing needle fixed to the tip of a needle bar, and an upper thread catching body. A pinching member that is disposed in the upper thread path between the pinch and the upper thread and that inserts the upper thread so that the upper thread can be pinched; and a releasing means that brings the pinching member into and out of the upper thread in the upper thread pinching state or the upper thread releasing state. An upper thread swinging prevention mechanism is provided, wherein the releasing means holds the holding member in the holding state only when the needle bar catches the upper thread loop near the bottom dead center.

[Operation] With the needle thread swinging prevention mechanism according to the present invention, when the rotary hook catches the loop of the needle thread formed below the sewing object, the engagement hole provided in the outer sleeve of the needle bar is , The position corresponding to the projecting body, the projecting body is projected from this engaging hole by the biasing body, and is clamped by this projecting body so that the sandwiching body clamps the upper thread so as to prevent the upper thread from swinging. Then, the upper thread of the rotary hook is properly captured.

Embodiments of the Invention Embodiments of the present invention will be described with reference to the drawings.

1 and 2 are views showing an embodiment of the present invention.

FIG. 1 is a partially cutaway side view showing a needle thread swinging prevention mechanism. In FIG. 1, 6 is a fixed shaft in a needle bar, which is fixed to a sewing machine head M.

Reference numeral 7 denotes an outer tube serving as a releasing means and a needle bar, in which a fixed shaft 6 is provided, a lower end of which is provided with a sewing needle and which is vertically moved in conjunction with the upper shaft of the sewing machine.

Ma is a metal ring which is fixed to the sewing machine head M to stabilize the vertical movement of the outer tube shaft 7.

Reference numeral 8 denotes a ball body as a releasing means, which is internally provided in a hole 10 provided on the side surface of the fixed shaft 6 and is urged outward by a spring 9 as an urging body.

On the other hand, 7a is an engaging hole provided in the outer pipe 7, and this engaging hole 7a is used when a loop of the upper thread is caught by the tip of the rotary hook as the upper thread catcher in a series of sewing operations. It is provided at the same height as the ball body 8. (In the figure, the outer tube is shown at the time of rising.) And, this engaging hole 7a
The opening length L in the vertical direction is longer than the outer shape of the ball body 8.

Further, 11 is a holding member, the upper end of each of which is fixed to the metal ring Ma so as to face the ball body 2
It consists of one plate.

FIG. 1 (b) is an external perspective view showing the holding member 11. In the figure, 11a is an inner plate made of an elastic material, 11b is an outer plate, and a through hole 11c is provided in the upper part.

And the upper thread 1 is, as shown in the drawing, the through hole 11c
It suffices that the outer plate 11b and the inner plate 11a be hung down through.

Next, the operation of the needle thread swinging preventing mechanism will be described with reference to FIG.

FIG. 3A shows a state in which the outer tube 7 is at the top dead center, that is, the sewing needle is at the top dead center, the rotary hook crosses the upper thread and the lower thread, and the balance tightens the upper thread. In this state, the ball body 8 is stored in the fixed shaft 6 by the outer tube 7.

The holding member 11 does not prevent the needle thread 1 from moving.

FIG. 2B is a view showing an upper thread swinging prevention mechanism when the upper thread forms a loop below the article to be sewn and is caught by the rotary hook. In this state, the ball 8 is It projects from the engagement hole 7a of the outer tube 7 by the bias of the spring 9.

Then, the ball body 8 is pressed so that the inner plate 11a of the holding member 11 is held by the outer plate 11b.

The holding of the upper thread 1 by the holding member 11 is performed while the outer tube shaft 7 is moved by the vertical opening length L of the engaging hole 7a during the loop catching of the upper thread by the rotary hook and before and after the upper thread. It is designed to hold 1.

As a result, it is possible to prevent the upper thread 1 from swinging due to the vertical movement of the sewing needle, etc. Also, since the upper thread 1 is not constantly pressed and the upper thread 1 is not handled vertically, the upper thread 1 is twisted. The problem of returning is prevented, and the rotary hook can properly catch the loop of the upper thread formed below the material to be sewn.

The holding member 11 that is intermittently brought into sliding contact with the needle thread can be used for a long period of time.

Next, another embodiment of the needle thread swinging prevention mechanism will be described.

The needle thread rocking prevention mechanism according to the present invention operates between an angle detector including a synchronizer for detecting the rotation angle of the upper shaft of the sewing machine and a signal from the angle detector to move the balance from the balance to the sewing needle. Hold the upper thread and move the solenoid back and forth.
Alternatively, it is constituted by a sandwiching means that drives the piezoelectric element in good swing motion.

In other words, this needle thread swinging prevention mechanism outputs an angle front and rear signal of the angle of the upper shaft when the rotary hook captures the loop of the upper thread by the angle detector, and the swinging of the upper thread is prevented by the pinching means. To do.

According to this needle thread swinging prevention mechanism, the timing for pressing the needle thread and the pressing time can be freely set,
It is possible to more appropriately capture the upper thread loop of the rotary hook.

[Effect of the Invention] Since the needle thread swinging prevention mechanism according to the present invention prevents the needle thread from swinging when the needle thread catcher catches the loop of the upper thread as described above, Appropriate seams can be formed and the quality of sewn products can be improved.

Further, the upper thread is clamped only when the needle bar is in the vicinity of the bottom dead center where the upper thread catcher catches the loop, so that the upper thread and the clamping member hardly make sliding contact. As a result, the upper thread does not move back further, and half-sewn stitches are not generated, and a part of the thread is not cut by the sword tip of the upper thread catcher. Furthermore, the mechanism itself can be used for a long period of time.

[Brief description of drawings]

FIG. 1 is a view showing an embodiment of a needle thread rocking prevention mechanism according to the present invention. FIG. 1 (a) is a partially cutaway side view showing the structure of the needle thread rocking prevention mechanism. FIG. 2B is an external perspective view showing the structure of the holding body, FIG. 2 is a view showing the action of the needle thread swinging prevention mechanism shown in FIG. 1, and FIG. Partially cutaway side view showing the upper thread rocking prevention mechanism, FIG. 2B is a partial cutaway showing the upper thread rocking prevention mechanism in which the projecting body projects and the nipping body holds down the swing of the upper thread. A side view and FIGS. 3A and 3B are external perspective views showing a rocking prevention mechanism as a conventional technique. In the figure, 1 ... upper thread 6 ... fixed shaft 7 ... outer tube 7a ... engaging hole 8 ... projecting body 9 ... biasing body 10 ... hole 11 ... sandwiching body

Claims (3)

[Claims] 1. A sewing machine that forms a stitch by cooperation of a balance, a sewing needle fixed to the tip of a needle bar, and an upper thread catcher, and is arranged in an upper thread path between the balance and the sewing needle. In addition, a pinching member for inserting the upper thread so that it can be pinched, and a releasing means for bringing the pinching member into and out of the pinching member so that the pinching member is in the upper thread pinching state or the upper thread releasing state are provided. A needle thread swinging prevention mechanism characterized in that the releasing means holds the holding member in a holding state only when the thread loop is caught. 2. A sewing machine that forms a stitch by cooperation between a balance, a sewing needle fixed to the tip of a needle bar, and an upper thread catcher, wherein the needle bar is provided in a needle thread path between the balance and the needle. A sandwiching member that is fixedly arranged on the sewing machine main body so as to face the vertical movement path and that is composed of two sandwiching plates having at least one elastic plate, and sandwiches or releases the upper thread by inserting the upper thread between them. The needle thread is fixedly arranged near the member and the needle thread catches the needle thread loop by the vertical movement of the needle bar. The needle thread engages the nipping member only in the vicinity of the needle bar bottom dead center to put the two nipping plates in the nipping state. A needle thread swinging prevention mechanism comprising: 3. A sewing machine which forms a stitch by cooperation of a balance, a sewing needle fixed to the tip of a needle bar, and an upper thread catcher, wherein the sewing machine main body is provided with an upper thread path between the balance and the sewing needle. A pinching member that is fixedly arranged and that inserts the upper thread so that it can be pinched, and a pinching member that holds the upper thread catcher near the bottom dead center of the needle bar that catches the upper thread loop. A needle thread swinging prevention mechanism comprising a control means for releasing the holding member at a disengaged position.