JPH0728968B2 - How to change the feed amount of the sewing machine - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for changing a feed amount of a sewing machine.

(Prior Art) Generally, a sewing machine has a feed adjusting mechanism for changing a feed amount. However, some special sewing machines have a constant feed amount and are not variable.

It is a so-called simple type.

For example, many home overlock sewing machines are of this simple type, and therefore a home overlock sewing machine will be described as an example. This simple sewing machine can sew only normal overedge stitches with a constant feed amount.

In addition to the stitches of the normal overlock stitch, the stitches of the ordinary overlock sewing machine include decorative stitches called roll stitches.
When this winding sewing is performed, it is necessary to replace the needle plate and the presser foot with dedicated ones, and to make the feed amount smaller than that in the case of normal overedging.

Therefore, in order to carry out winding sewing in addition to the usual overedging with a simple type, the needle plate and the presser foot are replaced with dedicated ones as described above, and the sewing machine has a complicated mechanism for adjusting the feed amount. I have to

(Purpose) An object of the present invention is to provide a sewing machine in which the movement loci of the feed dogs are substantially egg-shaped and the feed amount is set to be constant, and a plurality of different planar shapes are formed to form a plurality of stitches. It is equipped with a dedicated needle plate for the above, and is related to the replacement of the dedicated needle plate that is indispensable when selecting the stitches, and it is replaced with a dedicated needle plate that is set to have a different thickness depending on each stitch in advance. , Or when replacing the needle plate, add a spacer to the lower surface of the needle plate to change the height of the upper surface of the dedicated needle plate and change the amount of the feed dog from the needle plate to change the effective feed amount corresponding to the stitch. By changing the sewing machine, it is possible to form stitches with a feed suitable for each stitch without adding a complicated mechanism for adjusting the feed amount to the sewing machine as in the conventional example. It is to be able to greatly expand the range.

(Examples) The present invention will be described below with reference to examples. An example of an overlock sewing machine will be described below.

In FIG. 1, a sewing machine 1 is provided with a sewing portion 2 of an overlock sewing mechanism.

Although the feed mechanism of this overlock sewing mechanism is not shown, the movement locus of an arbitrary point on the uppermost surface of the feed dog is substantially elliptical as shown by the alternate long and short dash line in FIG. Is doing.

In the figure, the arrow indicates the direction of exercise.

As the stitches of the overlock sewing machine, there is a decorative stitch called a roll stitch 4 as shown in FIG. 3 in addition to the ordinary overedge stitch 3 as shown in FIG.

In order to form the overlock stitch 3, a dedicated presser foot 5 and a dedicated needle plate 6 are used with a constant feed.

That is, the overlock stitch 3 guides the vicinity of the cloth end cut by the knife 7 to the claw portion 6a of the needle plate 6, and the needle thread and the looper thread near the cloth end.
It is formed by intersecting with JIS B9070 seam symbol E12A model.

The winding stitch 4 guides the vicinity of the cloth end cut by the knife 7 to the claw portion 8a of the needle plate 8 for winding stitch, winds a part of the vicinity of the cloth end downward with a looper thread, and JIS B9070 seam symbol E12A. Formed by intersecting needle thread and looper thread in a form.

As described above, the shape of the needle plane is different between the overedging stitch and the winding stitch, and the needle plates 6 and 8 are dedicated and the presser foot is also dedicated although not shown.

Regarding the feed, it is necessary that the feed amount at the time of winding sewing be smaller than the feed amount at the time of overedging.

In the present invention, the needle plate 6 for overedging and the needle plate 8 for roll sewing, which are dedicated for each and indispensable, are made to change in height of the needle plate upper surface after the replacement, and the needle plate 6 and the needle plate 6 for winding are sewn. As shown in the figure, by changing the amount of the feed dog 9 from the needle plate 6 and the needle plate 8 at the highest position in the movement path, the amount of feed dog protrusion is shown in FIGS. 8 and 9, respectively. As described above, the effective feed amount is changed even if the movement trajectory of the uppermost surface of the feed dog 9 is constant. The arrow in FIG. 9 indicates the direction of movement.

To change the height of the upper surface of the needle plate after replacing the needle plate, first
As a method of, in addition to changing the thickness of the needle plate 6 and the needle plate 8,
As a second method, the needle plate 6 and the needle plate 8 may have the same thickness, and a spacer may be added to the lower surface of the needle plate when replacing them.

However, note the following points when changing the height of the throat plate upper surface.

That is, the vertical motion component of the feed dog which forms an egg-shaped movement of an arbitrary point on the uppermost surface of the feed dog is often obtained by the swinging motion with respect to the fixed center. The inclination changes with respect to the upper surface of the needle plate at each point of the trajectory.

Normally, the tangent plane of the uppermost surface of the feed dog (hereinafter, the tangent plane of the feed tooth) is parallel to the upper surface of the throat plate at the position where the uppermost surface of the feed dog comes out of the throat plate and at the position where it sinks (hereinafter, the retracted position of the feed dog) That is, it is preferable to set them so that they coincide with each other from the viewpoint of feeding efficiency.

For example, in FIG. 8, the fixed center is provided on the opposite side to the sewing up side, and the tangent plane of the feed dog 9 is parallel to the needle plate upper surface 6b at the retracted position, and the needle plate is simply thickened by a certain amount. If you change it to a different one or use a spacer to obtain the same result, the tangential plane of the feed dog will be higher on the sewing side at the retracted position after the replacement, so only the sewing side will be fed, and the cloth When the fixed center is provided on the sewing up side, on the contrary to the above, the sewing up side becomes lower at the protruding / retracting position of the feed dog, so that the cloth is contracted, which is not preferable.

Therefore, in the sewing machine in which the vertical motion component of the feed dog is obtained by the swing motion with respect to the fixed center, when changing the height of the needle plate upper surface, the tangential plane of the feed dog at the retracted position of the feed dog after replacement is changed. Care should be taken to match the inclination of the top surface of the throat plate with the inclination.

An example of a sewing machine in which the vertical motion component of the feed dog is obtained by a swinging motion with respect to a fixed center, and the fixed center is provided on the side opposite to the sewing up side.

In the case of this type, for the reason described above, when the needle plate is exchanged from the overedging sewing to the winding sewing, it is necessary to make the sewing up side of the upper surface of the needle plate higher than the opposite side. FIG. 10 shows an example in which a spacer 10 is used on the lower surface of the needle plate 8'for winding and sewn. The sew-up side is doubly folded and the opposite side is thickened. This makes it possible to match the inclination of the upper surface of the needle plate with the inclination of the plane of the feed dog at the retracted position of the feed dog. Needless to say, the spacer 10 is provided with a relief portion for the movement of the feed dog 9 although not shown.

Besides using the spacers, the front and rear thicknesses of the needle plate may be changed so that the same effect as in the case of using the spacers can be obtained.

As described above, according to the present invention, a simple sewing machine is used to compose a complicated mechanism for adjusting the feed amount of the sewing machine in connection with the presser foot and the needle plate of the needle plate, which are indispensable for each sewing. It is possible to change the effective feed amount and form a stitch with a feed suitable for each sewing, without adding.

(Effect) As described above, according to the present invention, in the sewing machine in which the movement locus of the feed dog is substantially an egg type and the feed amount is set to be constant, a needle plate dedicated to forming a plurality of types of stitches is provided. The height of the upper surface of the special needle plate is changed according to each stitch, and the amount of the feed dog from the needle plate is changed to change the effective feed amount corresponding to the stitch. By doing so, it is possible to form stitches with a feed suitable for each stitch without adding a complicated mechanism for adjusting the feed amount to the sewing machine as in the conventional example. A remarkable effect such as enlargement can be obtained.

[Brief description of drawings]

1 is a perspective view of an overlock sewing machine, FIG. 2 is a view showing a seam of a general overedged stitch, FIG. 3 is a view showing a seam of a roll stitch, and FIG. 4 and 5 are perspective views showing the state near the needle plate at the time of normal overedging and winding, respectively, in this order, and FIGS. 6 and 7 are, respectively, in this order during normal overedging and 8 and 9 are views showing a state where the feed dog is most protruded from the needle plate at the time of winding sewing, respectively, in this order, at an arbitrary point on the uppermost surface of the feed dog at the time of normal overedging and winding. FIG. 4 is a view showing the movement locus in relation to the upper surface of the needle plate, as viewed in the direction of arrow A in FIG. 4 and arrow B in FIG. 5, and FIG. 10 is a view showing an example in which a spacer is used in combination with a needle plate for winding sewing. . 6 is a needle plate dedicated to overedging, 8 is a needle plate dedicated to winding sewing, 9
Is a feed dog and 10 is a spacer.

Claims (1)

[Claims] 1. A sewing machine in which the movement loci of the feed dogs are substantially egg-shaped and a constant feed amount is set, and a plurality of exclusive needle plates having different plane shapes are formed to form a plurality of types of stitches. In connection with the replacement of the dedicated needle plate, which is indispensable when selecting the stitches, replace it with a dedicated needle plate that is set to have a different thickness depending on each stitch, or when replacing the needle plate. It is characterized in that a spacer is added to the lower surface of the needle plate to change the height of the upper surface of the dedicated needle plate to change the amount of the feed dog protruding from the needle plate to change the effective feed amount corresponding to the stitch. How to change the feed amount of the sewing machine.