JPS5830055Y2 - Female mechanism of overlock sewing machine - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a knife mechanism for an overlock sewing machine equipped with a variable knife position device.

For underwear, especially women's underwear such as shorts and slips, large seam allowances give a loose feel to the skin and are not preferred, so the side seam process involves stacking two layers of fabric and sewing the side edges. I tend to keep the seam allowance as narrow as possible.

However, when side-stitching items with a lace section on the bottom edge of the fabric, such as women's underwear such as shorts and slips, using an overlock sewing machine, the lace section is sewn as-is using a narrow hem width in the fabric section. Then, since the density of the fabric in the lace part is coarse, the tension of the sewing thread during seam formation causes the lace part to be squeezed and wound, and the seam cannot be formed as surely and beautifully as in the fabric part, and it also poses a problem in terms of strength. had.

This idea is designed so that the position of the knife mechanism in an overlock sewing machine can be changed, and when overlocking fabrics such as coarse lace, the position of the knife mechanism to cut the edges of the fabric can be changed and the needle The width from the falling position to the edge of the lace is widened and then sewn to obtain an edge that has the same narrow sewing width as when sewing cloth using a sewing diaphragm and has sufficient strength.

To explain this based on the drawings, FIG. 1 shows a cloth cutting device in a known overlock sewing machine, which is equipped with a lower knife 1 and a movable upper knife 11 that cuts the cloth in cooperation with the lower knife. , FIG. 2 shows the upper knife drive mechanism with the cover plate removed.

The lower knife 1 is fixed to a knife holder 2 with a fixture 3, and the knife holder 2 is loosely fitted onto a guide shaft 4 fixed to the sewing machine frame so as to be movable in the axial direction, and is rotated in one direction by a spring (not shown). The lower knife 1 attached to the holding base is biased and brought into elastic contact with the upper knife 11.

On the other hand, the upper knife 11 is removably attached to a knife holder 12 attached to the free end of the swing arm 13 (see FIG. 3).
3 is fixed to the end of the upper female shaft 14 at the base end.

A fork-shaped crank 15 is fixed to the upper female shaft 14, and a compression spring 16 is attached to the upper female shaft 14. The compression spring 16 urges the upper female shaft 14 to the left in FIG.
is brought into elastic contact with the frame via a washer 17.

19 is the small diameter part 19a at the upper end of the crank 15.
The rod is loosely fitted in the pin so as to be movable in the axial direction of the pin, and the large diameter portion 19b is fitted into an eccentric crank (not shown) which is interlocked with the main shaft of the sewing machine.

When the crank 15 swings via the rod 19 due to the eccentric crank, the upper female shaft 14 fixes the crank.
causes the swinging arm 13 to swing, and the upper knife 11 thereby moves up and down to perform a cloth cutting motion in cooperation with the lower knife 1. The upper knife also causes the swinging arm 13 to resist the compression spring 16 due to the above structure. When pushed in (see Figures 5A and B), its position moves horizontally, that is, to the right in Figure 5, and the lower knife 1, which is in elastic contact with the upper knife 11, also moves while maintaining the elastic contact state. It is understood that the cutting width of the fabric can be varied.

In the above configuration, the crank 15 is formed into a fork shape, and by sliding the pin 18 at the tip against the small diameter portion of the upper end of the rod 19, the upper female shaft 14 and the crank 15 fixed to the shaft are moved in the above direction. However, if the crank and the upper female shaft are connected so as to be movable only in the axial direction by a key or spline connection, the crank can be connected to the rod in a normal manner with a pin without forming it into a fork shape. be able to.

Next, the mechanism for pushing the swinging arm will be explained.

Figure 4 shows the pushing mechanism as seen from the back of the sewing machine. In the figure, 21 is a bell crank whose one end is connected by a chain of a foot pedal (not shown) and whose middle part is pivoted to the sewing machine frame.
The other end of the connecting rod 22 is connected to one end of the connecting rod 22 by a ball joint, and the other end of the connecting rod 22 has a lever 2 whose intermediate portion is pivoted by a pin 23 to an L-shaped block 24 fixed to the sewing machine frame.
The lever 25 is connected to one end of the lever 25 by a ball joint, the other end of the lever 25 is located outside the base of the swing arm 13, and the lever 26 is slidably fitted loosely into the connecting rod 22, and connected to connecting rods disposed on both sides thereof. 22, the position of which is adjustable by nuts 27, 27 screwed onto the arm 22. Although its free end is not shown in detail, it is a guide having a U-shaped cross section and fixed to the above-mentioned block 24. It fits into the groove 29 of the plate 28, thereby guiding the movement of the connecting rod 22 in the axial direction.

30 is a spring that biases the bell crank 21 in the counterclockwise direction in the figure.

This invention is constructed as described above, and when sewing coarse-density fabrics such as lace, the foot pedal is depressed and the bell crank 21 is moved clockwise in FIG. 4 against the action of the spring 30. Rotate and move the connecting rod to the right to lever 25.
, thereby pushing in the swinging arm 13 to move the upper knife 11 away from the needle drop position as described above, thereby widening the cutting width, that is, the width from the needle drop position to the fabric edge,
After being tightened by oversewing, the fabric will have the same sewing width as the oversewing, and will be able to wrap around the edges with sufficient strength.

In the above embodiment, a link mechanism operated by a foot pedal was used as the pushing mechanism for the swinging arm, but the same effect as in the above embodiment can also be obtained by using a pushing mechanism using an air cylinder, a solenoid, etc. can be given.

[Brief explanation of drawings]

Fig. 1 is a perspective view of the knife section of the overlock sewing machine, Fig. 2 is a partial perspective view of the knife drive mechanism, Fig. 3 is a partial perspective view of the upper knife variable mechanism, and Fig. 4 is the same as the above knife variable device. The perspective view and Figures 5A and 5B are partial longitudinal sectional views of the knife drive mechanism. 1... Lower knife, 2... Knife holding stand, 4
...Guide shaft, 11 ... Upper knife, 12.
... Scalpel holding stand, 13 ... Swinging arm, 14
......Upper female shaft, 15...Crank, 1
6... Compression spring, 19... Rod, 2
1...Bell crank, 22...Connecting rod, 25...Lever

Claims (1)

[Scope of utility model registration request] 1. In the female mechanism of an overlock sewing machine, the lower knife has a lower knife attached to the sewing machine frame and an upper knife that moves up and down by an upper knife drive mechanism linked to the sewing machine main shaft and performs cloth cutting work in cooperation with the lower knife. The knife is always urged to come into elastic contact with the upper knife by the action of a spring provided on the sewing machine frame, and the upper knife drive mechanism is configured such that the knife position of the upper knife can be moved in a direction perpendicular to the feeding direction.
However, the upper knife is provided with a separate pushing device for moving the upper knife in the above direction. 2. The knife mechanism for an overlock sewing machine according to claim 1, wherein the pushing device is a link mechanism operated by a pedal. 3. The female mechanism for an overlock sewing machine according to claim 1, wherein the pushing device is a device including an air cylinder. 4. The knife mechanism for an overlock sewing machine according to claim 1, wherein the pushing device is a device including a solenoid. 5. The upper knife drive mechanism includes an upper knife shaft that is rotatably and axially movably supported on the sewing machine frame, and a swinging arm that is fixed to the shaft and that attaches the upper knife directly or via a knife holder. and,
It consists of an eccentric crank that rotates in conjunction with the main shaft of the sewing machine, a crank attached to the upper knife shaft, and a swinging mechanism for the upper knife shaft that connects both lances to form a four-bar link mechanism consisting of a rod. 2. The female mechanism for an overlock sewing machine according to claim 1, wherein at least one of the shaft attachment parts of the mechanism is configured to be movable in the axial direction.