JPS649878B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a sewing machine equipped with an upper feed device that feeds cloth in cooperation with a lower feed dog by an upper feed dog that performs four movements including forward and backward movement and up and down movement.

JP-A No. 52-86844 as an upper feed device for sewing machines,
Those shown in Utility Model Application Publication No. 56-11772, Japanese Patent Publication No. 57-26795, etc. are known. In this device, the upper feed dog is rotatably supported in the vertical direction by a drive member that reciprocates in the feed direction, and is provided at the free end of the upper feed arm that is pressed down by a spring. is pushed up by the crank that swings up and down in conjunction with the main shaft at the bottom of the upper feed arm, that is, by the upward rotation of the crank, it is pushed up against the action of the spring, and the downward rotation of the crank However, since the spring always acts to push down the upper feed arm, when the sewing machine is stopped, the main shaft is in a state where it can freely rotate, and the upper feed arm is lowered. When the upper feed arm is in a lifted state, the upper feed arm will descend until the upper feed dog reaches the cloth on the throat plate or the throat plate, and the crank will also be pushed down. The vehicle descends to the bottom dead center or near the bottom dead center. This downward rotation of the crank becomes a problem when the crank is on its upward stroke when the sewing machine is stopped. This is because the main shaft, which is connected to the crank via a transmission mechanism, rotates in the opposite direction, resulting in skipped stitches when the sewing machine is started again and sewing begins.

Figures 1A to 1F show the stitch forming process of a hemlock stitch sewing machine using three threads. When the sewing machine is stopped at the stage where the thread exits the loop 4 of Return to the state shown in Figure 1C. In this state, unlike the one in the diagram, loop 4 is not hung on the right looper, so when the sewing machine is driven again, skipped stitches occur.The skipped stitch phenomenon occurs when the needle thread and the left looper thread are used. This problem occurs in a similar manner in over-edge sewing machines, and is particularly noticeable in sewing machines in which the upper feed dog acts rearward in the feed direction of the needle drop position.

In order to eliminate this skipped stitch phenomenon, it is possible to use a drive motor with a needle positioner so that the crank always stops at a fixed position, but using the above motor makes the sewing machine more expensive. I don't like it.

An object of the present invention is to use another simple means to prevent the rotation of the main shaft immediately after the sewing machine is stopped, thereby preventing the above-mentioned skipped stitch phenomenon from occurring.

One means to achieve the above object is to operate in conjunction with a crank, or to
216400 (Special Publication No. 1983-21513) and Patent Application No. 1983-
A sewing machine equipped with an upper feed device of the type proposed in No. 225294 (Special Publication No. 63-23303) includes an upper and lower feed mechanism linked to the drive side of the clutch, an upper needle mechanism, a knife mechanism, a looper mechanism, and other main shafts. Among various mechanisms in a sewing machine, a spring that acts in the opposite direction to the spring that pushes down the upper feed arm is provided on a suitable operating member, and the spring cancels the action of the former spring on the operating member, thereby rotating the main shaft. The aim is to prevent this from occurring. In the latter known vertical movement mechanism in which the upper feed dog is raised and lowered by a spring, the crank is pressed against the upper feed arm, and in the above-mentioned type proposed earlier by the applicant, the driving side of the clutch is pressed against the driven side, but the main shaft During one rotation, the upper feed arm rotates against the action of the latter spring in a certain range, and rotates with the help of the spring in other ranges. It does not cause any trouble. In other words, when the main shaft rotates during one revolution against the action of the latter spring, thereby lowering the crank, or when the driving side of the clutch rotates away from the driven side, the upper feed arm moves against the action of the former spring. As a result of the action, the upper feed arm descends with the crank, and rotates in the direction in which the latter's spring acts, causing the crank to rise, or the driving side of the clutch rotates in a direction that presses the driven side, the upper feed arm moves against the former's spring. It rises against the action of the spring.

Another means for achieving the above object is to apply brakes to appropriate operating members of the upper and lower feed mechanisms, upper needle mechanism, knife mechanism, looper mechanism, and other mechanisms provided in the sewing machine.

In one embodiment, a spring-loaded brake piece is applied to an eccentric cam fixed to the main shaft, so that when the upper feed arm is lifted, the eccentric cam is pressed against the brake piece.

In other embodiments, the upper feed arm moves in different paths when raised and lowered, e.g. when the upper feed arm is raised on a rod connected to an eccentric cam or on a lower feed carriage. A brake piece is provided to brake the rod or lower feed table by engaging with the rod.

Embodiments of the present invention will be explained below with reference to the drawings. Figure 2 shows an upper feed device of a sewing machine of the type proposed by the applicant in the above-mentioned Japanese Patent Publication No. 63-21513, that is, one end is connected to the crank 12 of the front and rear feed shaft 11. An upper feed arm 16 is attached to the shaft and has an upper feed dog 15 facing the lower feed dog 13 at its free end, an elastic device 17 that presses down the upper feed arm, and an upper feed arm 16 that is fixed to the vertical feed shaft 18 and is connected in the vertical direction. The crank pin 20 is slidably fitted into a fork 21 attached to the upper feed arm 16, and the crank pin 20 is oscillated in conjunction with the upper knife shaft 23, and the amount of the oscillation is equal to the amount of the crank shaft 25. A bifurcated lever 27 is loosely fitted in a rotatable manner to the vertical feed shaft 18, which is adjusted by adjusting the mounting position of a slider 26, which is slidably mounted on the vertical feed shaft 18.
is fixed to the vertical feed shaft 18, and the above-mentioned ammunition device 1
7, the collar 28 is provided with a clutch piece that removably engages with the clutch piece of the fork lever 27 in the circumferential direction. Interlocking upper knife 3
0 rises and the forked lever 27 rotates downward, the upper feed arm 16 and crank 22 are pushed down while the clutch piece is engaged by the action of the elastic device 17, and the upper feed dog 15 moves toward the throat plate. After its descent is stopped by the upper cloth or needle plate, the forked lever 27 further rotates to the bottom dead center, separating both clutch pieces, and the forked lever 27 reaches the bottom dead center. When the upper feed device of the sewing machine is reversed, both clutch pieces engage on the way up, and thereafter the crank 22 is raised against the action of the above-mentioned bullet device, and the upper feed dog is lifted. Of these,
This mainly shows the vertical movement mechanism, and while the upper feed dog is lifted, the action of the elastic device acts on the upper knife shaft, main shaft, and other mechanisms that are linked to this through both clutch pieces that engage. The forked lever 2 is designed to prevent rotation due to this action.
7, which balances the rotational torque by the ammunition device 17;
That is, a coil spring 33 that acts in the opposite direction to the bullet device to urge the fork lever 27 to rotate upward is hooked at its upper end to the sewing machine frame and at its lower end to a bolt 34 attached to the fork lever. (See Fig. 3) to prevent downward rotation due to the action of the bullet device when the sewing machine is stopped, and to prevent reverse rotation of the main shaft.

In the illustrated example, a coil spring is provided on the forked lever to counteract the action of the bullet device, but other mechanisms that operate in conjunction with the forked lever, such as the upper knife mechanism, upper needle mechanism, or main shaft, are equipped with coil springs, A torsion spring, leaf spring, etc. may be provided to balance the action of the bullet device.

Fig. 4 shows an example in which a coil spring 35 is wound around the upper knife shaft 23 of the upper knife mechanism, and Fig. 5 shows an example in which a coil spring 37 is wound around a swing shaft 36 that swings in conjunction with the main shaft (not shown) of the upper needle mechanism. An example in which the compression spring 39 is wrapped around the balance weight 38 of the swing shaft 36 is shown in FIG.
Each of the figures shows an example in which one end of the swing shaft 36 is locked and the swing shaft 36 is biased in one rotation direction.
FIG. 7 shows another embodiment for preventing reverse rotation of the main shaft when the sewing machine is stopped. A cam 42 is fixed to the main shaft 41, and the cam is loaded with a spring when the upper feed dog is lifted. This prevents rotation of the main shaft due to the action of the bullet device.

Instead of providing the cam 42 on the main shaft, the cam 42 may be provided on another rotating shaft or a swing shaft, and braking can be performed using a brake piece in the same manner as described above. A brake piece that directly engages and brakes when the upper feed dog is lifted may be provided for a member such as a feed base that moves along different paths when the upper feed dog is raised and when it is lowered. .

According to the sewing machine of the present invention, when the sewing machine is stopped, movement due to the action of the bullet device that presses down the upper feed arm is not exerted on various mechanisms, and reverse rotation of the main shaft is also prevented, which is different from conventional sewing machines. Unlike sewing machines equipped with a top feed device, skipped stitches do not occur at the beginning of sewing.

[Brief explanation of drawings]

Figures 1A to 1F are explanatory diagrams showing the seam formation process for edge stitching, Figure 2 is a perspective view of the vertical movement mechanism of the upper feed dog, Figure 3 is an elastic view of the main parts of the mechanism, 4th to 6th
Each figure shows a perspective view of another embodiment, and FIG. 7 shows a sectional view of still another embodiment. 15...Upper feed dog, 16...Upper feed arm, 17...
...Bullet machine device, 18...Vertical feed shaft, 22...Crank, 23...Upper knife shaft, 27...Forked lever,
33...Coil spring, 41...Main shaft, 42...Cam, 43...Brake piece.

Claims (1)

[Scope of Claims] 1. An upper feed arm that is pivotally supported by a member that reciprocates in the feed direction so as to be swingable in the vertical direction, and has an upper feed dog at its free end that faces the lower feed dog, and an upper feed arm. and a vertical movement mechanism including a crank that swings in the vertical direction in conjunction with a main shaft on the lower side of the upper feed arm and engages with the upper feed arm to move the arm up and down. In a sewing machine equipped with an upper feed device, the sewing machine is connected to an appropriate operating member of the various mechanisms of the sewing machine including the upper and lower feed mechanisms, upper needle mechanism, knife mechanism, looper mechanism, and other main shafts that are affected by the elastic device. A sewing machine characterized in that it is provided with means for preventing rotation of the main shaft caused by the action of the above-mentioned bullet device when the sewing machine is stopped. 2. The sewing machine according to claim 1, wherein said means is a spring that acts on the operating member in a direction opposite to that of said elastic device and is provided to cancel the action of said device. 3. The sewing machine according to claim 1, wherein the means is a braking device that restricts movement of the operating member when the upper feed arm is lifted. 4. The sewing machine according to claim 3, wherein the operating member is a shaft, a cam is fixed to the shaft, and the braking device is a spring-loaded brake piece applied to the cam.