JPS6219196B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a presser foot device for a sewing machine, and particularly to a presser foot device for a sewing machine that holds cloth between cloth holders and feeds it in any direction based on information stored in a memory element such as a PROM. .

Conventionally, this type of presser foot device was installed with a small gap between the presser foot fixed to the presser bar of the sewing machine and the fabric so that the presser foot could operate smoothly without resistance. When the presser foot rises from the lowest position, the friction between the fabric and the needle causes the fabric to rise until it touches the bottom surface of the presser foot. For this reason, the size of the loop that is created when the fabric is squeezed when the needle rises is not large enough to be caught by the tip of the sickle, and the loop is twisted and not caught by the tip of the sickle, resulting in skipped stitches. There was a drawback that caused

The present invention has been made in view of the above-mentioned conventional problems, and its object is to provide a presser foot device for a sewing machine that can obtain good stitches without skipping stitches.

In order to achieve the above object, the present invention provides an upper presser foot of an upper presser foot mechanism which is given a vertical feed motion from the main shaft of the sewing machine, and a lower presser foot of a lower presser foot mechanism which is given a vertical feed motion from the main shaft of the sewing machine. During the cloth feeding period when the needle is raised, the upper presser foot and the lower presser foot release the cloth, and when the needle descends and captures the thread with the tip of the hook, the upper presser foot and the lower presser foot release the cloth. It is characterized by being configured so that the cloth is held between the presser foot and the presser foot.

Further, the phase timing of the upper presser foot and the lower presser foot with respect to the needle can be adjusted individually, and the lower presser foot is configured to be able to move up and down parallel to the up and down movement of the needle.

Hereinafter, preferred embodiments of the present invention will be described based on the drawings. The needle bar 10 is reciprocated up and down from a sewing machine main shaft 12 via a known needle bar mechanism, and has a needle 14 attached to its lower end. Further, the sewing machine main shaft 12 gives a vertical feed motion to the upper presser mechanism 16 and the lower presser mechanism 18. Next, the configurations of these mechanisms will be explained individually.

Upper presser foot mechanism The presser rod 20 is pivotally supported by the sewing machine frame 22 and reciprocates up and down, and an upper presser foot 24 is attached to its lower end with screws 26. The presser bar holder 28 has a protruding shaft 30 and a protruding piece 32, and is fixed to the cloth presser bar 20 with a screw 36. The presser spring 38 is inserted outside the presser rod 20,
Its lower end contacts the presser bar holder 28, and the spring pressure is adjusted by an adjusting screw 40 screwed onto the sewing machine frame 22. The needle thread guide 42 is attached to the presser bar holder 28 with a screw 44.

A hollow adjustment screw 50 is screwed onto the mounting plate 48 which is attached to the sewing machine frame 22 with screws 46, and the tip of a spring guide rod 52 inserted into the hollow adjustment screw is brought into contact with the L-shaped fitting 54, and the L A bell crank 58 is attached via a shaped fitting using a stepped screw 56 using the stepped screw as a pivot point. One end of this bell crank is inserted into the protruding shaft 30 of the presser bar holder 28, and is regulated to prevent it from coming off by a stepped portion 62 of a stepped shaft 60 screwed onto the protruding shaft. A roller 68 is inserted into the end of the stepped shaft to be inserted into a long groove 146 of a bell crank guide 66 attached to the sewing machine frame 22 with a screw 64. The other end of the bell crank 58 is connected to a link 72 by a stepped screw 70, and this link is connected to a swinging arm 76 attached to a swinging shaft 74 by a stepped screw 78. The swinging arm 80 at the other end is connected to one end of a rod 84 by a stepped screw 86, and this rod is connected to the main shaft 12.
It is inserted into an eccentric shaft 82 attached to the. A push spring 88 is fitted on the outside of the spring guide rod 52.

Lower presser mechanism An eccentric wheel 90 is attached to the main shaft 12 of the sewing machine, and the tip of a rod 92 integrated with the eccentric wheel has a bell crank 98 fixed to one end of a swing shaft 96 with a stepped screw 94.
is connected to one arm of. Also, link 1 is attached to the other arm of the bell crank with a stepped screw 100.
02 is connected to one end, and the other end of this link is connected to an arm 106 by a stepped screw 104.
is attached to a swing shaft 108 which is pivotally supported by the sewing machine frame 22. The lower presser foot 110 has a hole 112 through which the needle 14 passes, and has protrusions 114 at both ends for guiding the vertical movement of the lower presser foot 110, and these protrusions are provided on the sewing machine frame 22. Guide groove 1
16, and a bifurcated groove 1 formed at the bottom thereof.
Rollers 126, 128 attached to the ends of swing arms 122, 124 are fitted into the rollers 18, 120, and the swing arms are attached to swing shafts 130, 132, respectively.

A throat plate 134 attached to the sewing machine frame 22 has a hole 136 into which the protrusion 112a of the hole 112 of the lower presser foot 110 is loosely fitted. Further, the sewing machine main shaft 22 rotationally drives a known hook 138. The lower cloth holder 140 is used to feed the cloth in the X-X, Y-Y directions in FIG. to feed the cloth.

In order to make the vertical movement of the lower presser foot 110 parallel to the vertical movement of the needle 14, the positions of the swing shafts 130 and 132 are symmetrical to the vertical movement position of the needle bar 10, as shown in FIGS. Installed, bell crank 98
The distance from the center of the swing shaft 96 of the swing arm 122 to the stepped screw 100 is set equal to the distance from the center of the swing shaft 108 of the arm 106 to the stepped screw 104. The distance from the center to the roller 126 and the distance from the center of the swing axis 96 of the swing arm 124 to the roller 128 are also set to be equal.

Next, the operation of the presser foot device of the present invention having the above structure will be explained. As shown in FIG. 2, the rotation of the sewing machine main shaft 12 causes the needle 14 to rise from the lowest point.
At the time when the tip of the hook catches the loop of upper thread, the upper fabric presser foot 24 and the lower fabric presser foot 110 are at the timing where the fabric is being clamped, and the needle 14 rises above the fabric 144 and is moved by a fabric feeding device (not shown). During the period when the cloth is being fed, the upper presser foot 24 is raised and the lower presser foot 110 is lowered, as shown in FIG.

More specifically, the upper presser mechanism 16 has a rod 84 and an arm 80 from an eccentric ring 82 attached to the main shaft 12.
A constant rocking motion is applied to the rocking shaft 74 through the
This momentum transmits a swinging motion to the bell crank 58 via the arm 76 and the link 72 using the stepped screw 56 as a fulcrum. One end of this bell crank 58 is inserted into the protruding shaft 30 of the presser bar holder 28, so that
The presser bar holder 28 is guided by the rollers 68 of the stepped shaft 60 in the long groove 146 of the bell crank guide 66, and slides up and down. Therefore, the presser bar 20 and the upper cloth presser foot 24 move up and down via the presser bar holder 28. The pressing spring 88 normally controls the position of the bell crank 58 by bringing the L-shaped fitting 54 into contact with the bell crank guide 66 via the spring guide rod 52.

The lower presser foot 110 of the lower presser foot mechanism 18 transmits its swing motion to a swing shaft 96 attached to a bell crank 98 via an eccentric wheel 90 attached to the sewing machine main shaft 12 via a rod 92.
The same amount of rocking as the rocking shaft 96 is applied to the rocking shaft 108 via the arm 106. The rollers 126 and 128 attached to the tips of the forked groove 1
8,120, so the sewing machine frame 2
It is regulated by the protruding piece 114 guided by the second guide groove 116 and moves up and down parallel to the needle 14.

The timing of the upper presser foot 24 with respect to the vertical movement of the needle 14 is determined by the mounting phase of the eccentric ring 82 with respect to the main shaft 12, and the timing of the lower presser foot 110 with respect to the upper presser foot 24 is determined by the mounting phase of the eccentric ring 90 with respect to the main shaft 12. Determined by phase.

As described in detail above, the present invention allows the upper presser foot 24 and the lower presser foot 110 to not pinch the cloth during the feeding period of the cloth 144, and to smoothly feed the cloth without applying any resistance to the cloth, so that the needle 14 descends. After that, when the tip of the hook catches the upper thread loop, the fabric 144 is securely held between the upper presser foot 24 and the lower presser foot 110, so the upper thread loop is not twisted or made smaller. Since it can be caught reliably, good stitches can be obtained without skipping stitches. Moreover, the lower presser foot 110 has needle 1.
Since the vertical movement is obtained in parallel to the vertical movement of the needle 4, the hole 11 is moved regardless of the raised position of the needle 14.
It is possible to prevent deformation of the loop that provides a certain gap between the two loops. Furthermore, even when the capture timing of the needle 14 and hook tip is changed depending on the sewing material, the phases of the upper presser foot 24 and the lower presser foot 110 relative to the needle 14 are determined by the mounting timing of the eccentric ring 82 and the eccentric ring 90 relative to the main shaft 12, respectively. By adjusting the phase, it is possible to prevent skipped stitches.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of the device of the present invention, Fig. 2 is a left side view of Fig. 1 showing a state in which the cloth is held between an upper presser foot and a lower presser foot, and Fig. 3 is the same view as above in a state in which the cloth is fed. Fourth
The figure is an exploded perspective view of the upper presser mechanism, and Figure 5 is the first
FIG. The same members in each figure are given the same reference numerals, 10 is the needle bar, 12 is the sewing machine main shaft, 14 is the needle, 16 is the upper presser foot mechanism, 18 is the lower presser mechanism, 20 is the cloth presser bar, and 22 is the sewing machine. Machine frame, 24 upper cloth presser, 26 screw, 28 presser bar holder, 30 protruding shaft, 32 protruding piece, 36 screw, 38 presser spring, 40 adjusting screw, 42 upper thread guide, 48 is a mounting plate, 52 is a spring guide rod, 58 is a bell crank, 60 is a stepped shaft, 62 is a stepped portion, 66 is a bell crank guide, 7
2 is a link, 74 is a swing shaft, 76 and 80 are swing arms, 82 is an eccentric, 84 is a rod, 86 is a stepped screw, 88 is a push spring, 90 is an eccentric, 92 is a rod, and 96 is a swing. Moving shaft, 98 is bell crank, 102
is the link, 106 is the arm, 110 is the lower presser foot, 11
2 is a hole, 114 is a protrusion, 116 is a guide groove, 11
8, 120 are bifurcated grooves, 122, 124 are swing arms,
130, 132 are rocking shafts, 134 is a throat plate, 136
is a hole, 138 is a hook, 140 is a lower cloth holder, 14
2 is an upper cloth holder, and 144 is a cloth.

Claims (1)

[Scope of Claims] 1. An upper fabric presser foot of an upper fabric presser mechanism to which a vertical feed motion is applied from the sewing machine main shaft, and a lower fabric presser foot of a lower presser mechanism to which a vertical feed movement is applied from the sewing machine main shaft, so that the needle rises. During the cloth feeding period, the upper presser foot and lower presser foot release the cloth, and when the needle descends and captures the thread with the tip of the hook, the upper presser foot and lower presser foot clamp the cloth. A presser foot device for a sewing machine, characterized in that it is configured as follows. 2. A sewing machine presser foot device according to claim 1, in which the phase timing of the upper presser foot relative to the needle and the lower presser foot relative to the needle can be individually adjusted. 3. A sewing machine presser foot device according to claim 1, which has a lower presser foot that can move up and down parallel to the up and down movement of the needle.