JPS6131753Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to a needle thread loop control mechanism for a sewing machine, in particular, it holds a bobbin with hook thread, rotates in conjunction with the main shaft of the sewing machine, captures the needle thread loop, and rotates around the bobbin. A rotary hook that releases the needle thread loop after expanding the needle thread loop, and a thread take-up that is linked to the main shaft of the sewing machine, loosens the needle thread that the rotary hook captures and expands, and picks up the released needle thread loop from the rotary hook. The present invention relates to a needle thread loop control mechanism in a sewing machine equipped with a needle thread loop control mechanism.

In conventional sewing machines of this type, the hook of the rotary hook captures the needle thread loop created when the needle rises slightly from the lowest point, and the loop gradually expands as it goes around the bobbin. After passing around the bobbin, the needle thread loop is released from the hook, and then the needle thread loop is picked up by the thread take-up and is locked to the needle thread loop locking tail of the rotary hook, and passes through the inner hook locking section. and released from the tail,
The smaller needle thread loop becomes entangled with the hook thread taken up through the needle hole in the needle plate, forming a lockstitch stitch.

However, the needle thread loop below the needle hole of the throat plate, which passes through the inner hook stopper and is released from the tail of the rotary hook, rotates between the time it is captured by the hook of the rotary hook and the time when it is in this state. The thread twists due to friction with the hook and tail of the rotating hook, and as a result, a "kink" occurs in the needle thread loop below the needle hole in the throat plate that is completely released from the rotating hook. The frictional resistance with the fabric increases, or the needle thread loop released from the rotary hook comes into contact with the feed gear that moves the fabric forwarding near the needle hole of the needle plate, increasing the frictional resistance. When the needle thread loop is picked up by the thread take-up, the frictional resistance prevents the needle thread loop from being picked up completely, and a portion of the needle thread loop remains on the underside of the fabric, creating an unsightly seam and reducing the commercial value of the sewn product. There were some drawbacks that lowered the quality.

This device has a loop guide in the needle thread loop ascending path between the lower part of the needle hole in the needle plate and the upper part of the rotary hook that contacts and guides the needle thread loop that has been released from the rotary hook and has come up from the inner hook stop. By providing this, the purpose is to eliminate the above-mentioned conventional drawbacks.

Examples of this invention will be described below with reference to the drawings.
Reference numeral 1 designates a well-known rotary hook, the outer hook 2 of which rotates counterclockwise in conjunction with the main shaft of the sewing machine (not shown), and includes a hook 3 for catching a needle thread loop and a tail portion 4 for locking the needle thread loop. form.

Reference numeral 5 designates a well-known inner hook, and although it will not be described in detail, a rail portion on the outer circumference is loosely fitted into a circular groove formed on the inner circumferential surface of the outer hook 2, and a bobbin case support shaft 6 that projects horizontally in the center is provided. , an inner hook retaining recess 7 on the upper front surface and a bobbin case retaining groove 8 on the right front surface are formed.

Reference numeral 9 denotes a bobbin case, which holds a bobbin (not shown) with hook thread therein, and is loosely fitted onto the support shaft 6, and its claw portion 10 is loosely fitted into the retaining groove 8 of the inner hook 5, so that it does not rotate. Lock it like this.

Reference numeral 11 designates an inner hook stopper whose base is fixed to the lower surface of the sewing machine bed and whose tip is loosely fitted into the inner hook stopper recess 7 of the inner hook 5 to prevent the inner hook 5 from rotating following the rotation of the outer hook 2. do.

12 is a needle thread loop control body made of a metal plate;
As shown in the figure, a flat mounting surface 13, an inclined loop presser 14 and a flat guide surface 15 are integrally bent at the free end. A cup-shaped portion 16 formed by squeezing is provided on the guide surface 15, and a loop guide hole 17 is formed therein. Note that the height from the lower surface of the attachment surface 13 to the upper end surface of the cup-shaped portion 16 of this needle thread loop control body 12 is slightly higher than the height from the upper surface of the attachment portion 18 of the bed to the lower surface of the throat plate 19. It is formed.

Therefore, when the mounting surface 13 of the needle thread loop control body 12 is fixed to the upper surface of the mounting portion 18 with the screw 20, the upper end surface of the cup-shaped portion 16 is slightly above the lower surface of the throat plate 19, and then the throat plate 19 is fixed. When fixed to the upper surface of the bed, the cup-shaped portion 1 of the needle thread loop control body 12
The upper end surface of the cup-shaped portion 16 is pushed by the lower surface around the needle hole 21 of the throat plate 19 and is bent, and the upper end surface of the cup-shaped portion 16 is bent by the elastic force of the needle thread loop control body 12.
As shown in FIG. Moreover, it extends along the outer peripheral edge of the rotary hook 1.

Reference numeral 22 denotes a feed dog, which performs four movements for feeding the cloth 24 within the feed dog hole 23 of the throat plate 19 in conjunction with the sewing machine mechanism.

This invention has the above configuration, and the operation will be explained next.

When the needle pierces the cloth 24, passes through the needle hole 21 of the needle plate 19 and the loop guide hole 17 of the guide surface 15 of the needle thread loop control body 12, and rises slightly after reaching the lowest point, the needle The needle thread that has passed through the cloth 24 is strained by the cloth 24 to form a needle thread loop. This needle thread loop is captured by the hook 3 of the outer hook 2, and a portion of the loop contacts the lower part of the cup-shaped part 16 of the loop guide hole 17, and the tension of the needle thread loop pushes the cup-shaped part 16 upward. acts, but
Since the upper end surface of the cup-shaped portion 16 is in elastic contact with the lower surface of the throat plate 19, the needle thread loop control body 12 does not vibrate up and down due to the elasticity of the needle thread loop.

Furthermore, this needle thread loop is gradually enlarged by the outer hook 2 so that the loop goes around the inner hook 5 that holds the bobbin case 9. be freed and become free. At this time, this large needle thread loop 2
The needle thread 5 tries to spring upward in the direction of rotation of the outer hook 2 of the rotary hook 1 due to the inertial force of the needle thread loop as shown by the two-dot chain line in Figure 1, but the needle thread that has sprung up The loop 25 is the loop presser 1 of the loop control body 12.
The needle thread loop is then picked up by a thread take-up (not shown) and gradually becomes smaller, and passes between the recess 7 of the inner hook 5 and the hook thread stopper 11. Furthermore, this needle thread loop is connected to the guide surface 15 of the needle thread loop control body 12.
The needle thread loop is guided up from the lower surface into the loop guide hole 17 of the cup-shaped portion 16, taken up through the needle hole 21 of the throat plate 19, and thus released from the rotary hook. The thread is prevented from fraying on the lower surface, is smoothly picked up without contacting the four-moving feed dog 22, other parts, etc., and is entangled with the hook thread (not shown) to form a final stitch in the fabric.

As described above, this device contacts and guides the needle thread loop released from the outer hook and pulled up from the inner hook stop in the ascending path of the needle thread loop between the lower part of the needle hole of the needle plate and the upper part of the rotary hook. Since a loop guide hole is provided to prevent the needle thread loop from passing through the inner hook thread stopper, the needle thread loop can be prevented from fraying on the bottom surface of the throat plate, and the needle thread loop can be inserted into the feed dog that moves four times on the bottom surface of the throat plate or the bottom surface of the throat plate. Since the needle thread does not come into contact with other placed parts, etc., and no irregular frictional resistance is generated on the needle thread, the needle thread loop is not picked up completely by the thread take-up and remains on the underside of the fabric, and is always picked up securely. This has the effect of forming normal lock stitches and improving the commercial value of sewn products.

In addition, as another embodiment, the cup-shaped portion 16 shown in FIGS. 1 and 2 may be formed to protrude from below the needle hole 21 of the needle plate 19, and the same effect as in the above embodiment can be obtained.

[Brief explanation of the drawing]

Figure 1 is a front view of the rotary pot with a part cut away.
FIG. 2 is a perspective view of the needle thread loop control body. In the figure, 2 is an outer hook, 3 is a hook, 5 is an inner hook, 9 is a bobbin case, 12 is a needle thread loop control body, 15 is a guide surface, and 17 is a loop guide hole.

Claims (1)

[Scope of Claim for Utility Model Registration] Holds a bobbin with hook thread, rotates in conjunction with the main shaft of the sewing machine, captures the needle thread loop, expands the needle thread loop so that it goes around the inner hook, and then the needle thread loop In a sewing machine equipped with a rotary hook that releases the loop of needle thread, and a thread take-up that is linked to the main shaft of the sewing machine and loosens the needle thread that is captured and expanded by the outer hook of the rotary hook, and picks up the needle thread loop released from the outer hook, A cup-shaped loop guide is fixedly arranged below the needle hole, and the upper side is close to the needle hole and the lower side is widened, and it contacts and guides the needle thread loop that has been released from the outer hook of the rotary hook and has come out from the inner hook stop. A sewing machine needle thread loop control mechanism that prevents the needle thread loop from fraying.