JPS607660Y2 - blind stitch sewing machine - Google Patents

Description

[Detailed explanation of the idea] This invention relates to the improvement of blind stitch sewing machines.

Conventionally, in the jump stitching device of this type of sewing machine, the upper part of the swinging rod for swinging the cloth lifting rib is slidably contacted with the upper eccentric cam so as to be able to move up and down slightly, and the upper part of the swinging rod for swinging the cloth raising rib is slidably contacted with the upper eccentric cam so that it can be moved slightly up and down. It is known that a lower eccentric cam is fitted, and the lower part of the swinging rod is connected to a cloth raising rib via a connecting link.

In this conventional device, when sewing without jump stitching (hereinafter referred to as normal stitching), the upper eccentric cam is stopped, and the upper end of the swinging rod in contact with the cam is used as a fulcrum, and the swinging rod is moved to the lower eccentric position. The rotation of the cam causes the cam to swing, and the movement is transmitted to the fabric lifting rib via the connecting link, causing it to swing. When the needle picks up the fabric, the fabric is pushed up by the upper edge of the fabric lifting rib. None, in such a state, the needle slides on the upper edge of the cloth raising rib and enters the cloth, and after the needle has scooped up the cloth, the cloth raising rib is swung to position the needle release step below the needle. , so as not to interfere with the needle going further into the fabric to meet the looper.

On the other hand, when performing jump stitching, while rotating the lower eccentric cam in the same manner as described above, the upper eccentric cam is rotated in the opposite direction to the lower eccentric cam and at half the rotation speed, that is, the lower eccentric cam rotates once. The upper eccentric cam rotates at such a speed that it makes half a revolution while the needle is scooping up the cloth, and once every two
At this time, the needle release stepped portion of the fabric raising rib is positioned below the needle.

In short, the two eccentric cams work together to change the swing pattern of the cloth lifting rib, and when the needle crosses the cloth, the depth of the needle's scooping into the cloth is made shallower every second time. , jump stitching is performed.

By the way, as mentioned above, when performing normal stitching, conventional blind stitch sewing machines stop the upper eccentric cam, slide the upper part of the swinging rod into contact with it, and swing the swinging rod using this sliding contact point as a fulcrum. Because of this, the upper eccentric cam must be stopped and fixed at a fixed position in order to maintain the swing range of the swing rod at a constant level. A stopping device is required, which has the drawback of increasing costs.

Furthermore, since it is necessary to stop the upper eccentric cam during normal stitching and rotate the upper eccentric cam during jump stitching, there is a drawback that a clutch device is required to control the rotation and stopping of the upper eccentric cam.

This invention was made in order to eliminate the above-mentioned drawbacks, and by using a switching plate with guide parts such as special holes, it is possible to eliminate the need for a fixed position stop device and a clutch device that were previously required. The purpose is to provide a sewing machine.

This invention will be explained below based on embodiments shown in the drawings.

In this specification, the front refers to the left side in Figure 1, the rear refers to the right side in Figure 1, the left refers to the left side in Figure 2, and the right refers to the right side in Figure 2.

A sewing machine arm 2 is provided on the side of a machine frame 1 of the blind stitch sewing machine in a forward-protruding manner, and a needle shaft 3 is housed in the arm 2, and its front end passes through the arm 2 and projects forward. , a needle attachment arm 4 is attached to its protruding end, and a blind stitch needle 5 is attached to it.

A fixed base 6 is attached to the arm 2, and the fixed base 6 is formed with a long hole-shaped cloth-exposed open lower part, and facing the open lower part, a feed dog 8 is provided which moves upward, forward, downward, and backward. It is located.

At the front of the fixed base 6, there is a shaft support 1 with a shaft 9 projecting laterally.
0 is attached to the shaft 9, and the tip of the presser foot 11 is biased downward by a spring (not shown).The presser foot 11 is loosely fitted with the tip of the presser foot 11 facing the lower part with the tip open. A cloth raising rib 12 is positioned so as to come into contact with the cloth raising rib 12 from below, and a needle release stepped portion 13 is formed at the rear of the cloth raising rib 12.

The cloth raising rib 12 is fixed to a pivot shaft 14 that is loosely fitted to a hanging bracket 16 of the bed 15, and is configured to swing back and forth.

The bed 15 is pivotally attached to the machine frame 1 by pins 17 and is able to swing vertically.

The bed 15 is biased in a direction to raise the free end by a tension spring (not shown).

A bracket 18 on the desired side is protruded from the inner surface of the front end hanging wall of the bed 15, and the pin 1 is loosely fitted into the bracket 18.
A pair of left and right swinging arms 20, 20 are pivotally mounted to the fixed base 6 so as to be located below both sides of the opening lower part of the fixed base 6.
A presser foot 21.21 is pivotally attached to the upper end of the 0, 20, and the swinging arm 20.20 is attached by springs 22, 22 so that the presser foot 21, 21 comes into close contact with the lower surface of the fixed base 6. Forced.

The cloth W is configured to pass between the presser foot 11 and the cloth raising rib 12 and between the presser foot 21 and the feed dog 8.

A short link 23 is attached to the pivot shaft 14 of the cloth raising rib 12, one end of an f-shaped connecting link 24 extending in the front-rear direction is pivotally attached to the short link 23, and the other end is connected to the cloth raising rib 1.
It is pivotally attached to the lower end of the swinging rod 25 for swinging the swinging rod 2.
A lower eccentric cam 28 is fitted into the through hole 27 of the overhanging portion 26 formed at 5, and a gear 29 is integrally formed on the left side of the lower eccentric cam 28, as shown in FIG.
The gear 29 and the lower eccentric cam 28 are fitted onto a driving shaft 30 which is rotated by a motor or the like, and the driving shaft 30 is loosely fitted into the vertical walls 1a, la of the machine frame 1.

The gear 31 that meshes with the gear 29 has a pitch circle 2 of the pitch circle of the gear 29.
It has a double pitch circle and rotates at half the rotational speed of the gear 29, and on the right side there is an upper eccentric cam 3.
2 is integrally formed to protrude, and the upper eccentric cam 32 and the gear 31
is loosely fitted onto a shaft 33 extending between the vertical walls 1a and la of the machine frame 1, and an annular eccentric groove 34 along the upper eccentric cam 32 is formed on the right side surface of the gear 29.

A tension spring 37 for bringing the upper end of the swinging rod 25 into sliding contact with the upper eccentric cam 32 is fixed to the spring receiver 35 at the upper end of the swinging rod 25 and the spring receiver 36 of the machine frame 1.

A through hole 38 penetrating in the left-right direction is formed in the upper part of the swinging rod 25, and a switching pin 39 is slidably fitted into the through hole 38, and the left end of the switching pin 39 can be loosely fitted into the eccentric groove 34. A spring 40 that biases the head 39a in the direction of fitting into the eccentric groove 34 is fitted into the main body 39h of the switching pin 39, and one end of the spring 40 is connected to the head 39a. Furthermore, the other end is adapted to abut against a closing plate 41.

The closing plate 41 is fixed to the swinging rod 25 by screws 42 and has a hole 43 concentric with the through hole 38 .
The switching pin body 39b protrudes laterally to the outside by penetrating through it.

The right end of the switching pin body 39b is connected to the arcuate hole 45 of the switching plate 44.
In order to prevent the switching plate 44 from being pulled out from the switching pin 39, a washer 46 having a diameter larger than the width of the circular arc hole 45 is fitted into the switching pin body 39b, and the washer 46 is inserted into the switching pin body 39b. There is a large diameter portion 39 at the end of the main body 39b to prevent
c is formed.

The surface of the washer 46 in contact with the switching plate 44 is connected to the switching plate 44.
A convex arc surface 46a toward 4 is formed.

The switching plate 44 has a biased shape as shown in FIGS. 1 and 3, and is loosely fitted onto the shaft 33 using its central hole 47 so as to swing around the shaft 33. ing.

The arcuate hole 45 of the switching plate 44 has a normal stitched portion 45a and a jump stitched portion 45b, and the normal stitched portion 45a is located at a position where the swinging rod 25 is not operated by the upper eccentric cam 32. The switching pin 39 is configured to be fixed in such a way that it is allowed to move in the vertical direction but not moved in the front and rear directions.

In other words, the width of the normal stitched portion 45a is equal to the width of the switching pin body 39.
b, and the length from the center of the shaft 33 to the edge of the normal sewing part 45a on the shaft 33 side is equal to the diameter of the shaft 33.
The length from the center of the upper eccentric cam 32 to the longest outer edge of the upper eccentric cam 32 is equal to the length, and the length of the normal stitched portion 45a is set to allow vertical movement of the switching pin 39 by the lower eccentric cam 28.

On the other hand, the jump stitch portion 45b has a shape that allows the switching pin body 39b to move in the vertical and horizontal directions, and allows the swinging rod 25 to be freely moved by the upper eccentric cam 32.

In other words, the width of the jump stitch portion 45b is equal to the width of the switching pin body 39.
b and twice the eccentricity of the upper eccentric cam 32, and the length from the center of the shaft 33 to the edge of the jump stitch portion 45b on the shaft 33 side is The length is set to be equal to or less than the length to the shortest outer edge of the upper eccentric cam 32, and the length of the jump stitch portion 45b is set to allow vertical movement of the switching pin 39 by the lower eccentric cam 28.

Switching plate 4 provided with normal stitched portion 45a of arcuate hole 45
A portion 4 is a thick wall portion 44a, and an inclined surface 44c is formed between the thick wall portion 44a and the thin wall portion 44b.

Therefore, the switching pin 39 is connected to the thick part 44a (normally sewn part
When in position a), the switching pin 39 is pulled to the right against the elastic force of the spring 40, and its head 39a is aligned with the eccentric groove 34.
When the switching pin 39 is located in the thin part 44b (jump stitch part 45b), the head 39a is fitted into the eccentric groove 34 by the force of the spring 40.

The reason why the convex arc surface 46a is formed on the washer 46 is to allow the washer 46 to smoothly climb onto and descend from the inclined surface 44c.

Pin 4 fitted into end hole 48 formed in switching plate 44
As shown in FIG. The guide plate 52 is movably fitted into a long hole 53, and the guide plate 52 is fitted with a screw 5.
4 to the machine frame 1, one end of a torsion spring 56 is fitted into a hole 55 made in the guide plate 52, and the other end is attached to a head pin 51.

The operating portion 50a of the operating lever 50 protrudes to the outside through a long hole 57 formed in the machine frame 1.
By moving up and down by hand, the switching plate 44 can be swung.

The spring 56 is configured to use its own expanding force to fix the operating lever 50 at the lower limit position or upper limit position desired by the operator.

Next, the operation of the blind stitch sewing machine will be explained.

When the operating lever 50 is moved to the lower limit position, that is, the position shown by the solid line in FIG. 1, normal sewing is performed.

That is, when the operating lever 50 is at the lower limit position, the switching pin 39 is fitted into the normal stitched part 45a of the circular arc hole 45, so the upper eccentric cam 32 rotates via the drive shaft 30, gear 29, and gear 31. Even if the upper eccentric cam 32 is moved, the upper part of the swinging rod 25 is not operated.

Therefore, as only the lower eccentric cam 28 rotates, the swinging rod 25 swings back and forth about the switching pin 39.

This rocking motion is converted into a back-and-forth rocking motion of the cloth raising rib 12 via the connecting ring 24 and the short ring 23, and when the needle 5 scoops up the cloth W by this movement, the upper edge of the cloth raising rib 12 W is pushed up, and in this state, the needle 5 slides on the upper edge of the cloth raising rib 12, and the cloth raising rib 12, which has entered the cloth W, is swung forward to release the needle relief stepped portion 13. It is positioned below the needle 5 so as not to prevent the needle 5 from further entering the cloth W to meet the looper (not shown), and after the needle 5 is pulled out of the cloth W, the next needle 5 is In preparation for blind stitching, the upper edge of the cloth raising rib 12 is positioned on the needle passage path or slightly below it.

On the other hand, to perform jump stitching, the operating lever 50 is moved to the upper limit position, that is, the position shown by the dashed line in FIG. 1, and the switching plate 44 is rotated clockwise in FIG. It is preferable to position the jump stitch portion 45b of the hole 45.

With this operation, the swinging rod 25 pulled by the tension spring 37 comes into sliding contact with the upper eccentric cam 32, and as the switching plate 44 rotates, the washer 46 moves against the inclined surface 44.
c and reaches the thin part 44b of the switching plate 44, the head 39 of the switching pin 39 is moved by the elastic force of the spring 40.
a fits into the eccentric groove 34.

Therefore, even when a force stronger than the pulling force of the sewing tension spring 37, that is, a force so strong that the upper part of the swinging rod 25 does not follow and contact the upper eccentric cam 32, acts on the cloth lifting rib 12, etc., the eccentric groove Since the head 39a fitted into the eccentric groove 34 comes into contact with the outer circumferential surface of the eccentric groove 34 and its further movement is restricted, a force is applied to the swinging rod 25 via the switching pin 39 so as to direct it toward the upper eccentric cam 32. Therefore, there are disadvantages due to the swinging rod 25 not following the upper eccentric cam 32, for example, a predetermined feed amount cannot be obtained due to the fabric lifting rib 12 being in a fixed state, or a large force may be removed. As a result, the swinging rod 25 is pulled by the tension spring 37 and suddenly collides with the upper eccentric cam 32, causing noise, or furthermore, the cloth lifting rib 12 becomes fixed and the needle 5 scoops the cloth W. As the needle 5 is further sewn in, the thick part of the base end slides into contact with the upper edge of the cloth raising rib 12, and the needle 5 is forcibly curved upward by the cloth raising rib 12. This makes it possible to minimize the disadvantages that the looper (not shown) collides with the looper (not shown) and does not draw the set trajectory.

Note that the eccentric groove 34 is formed by the lower eccentric cam 28 on the swinging rod 2.
The size is such that the switching pin 39 is allowed to move up and down within the eccentric groove 34 as the pin 5 moves up and down slightly.

Due to the above state, the swinging rod 25 is rotated by the upper eccentric cam 32 which is rotated in the opposite direction through the lower eccentric cam 28 and the gear 29° 31 at half the rotational speed of the swinging rod 25. You will be shaken.

The initial positional relationship between the eccentric point of the upper eccentric cam 32 and the eccentric point of the lower eccentric cam 28 is as follows.

That is, the eccentric point of the upper eccentric cam 32 is on the virtual horizontal line passing through the center point of its shaft 33 and is behind the center point, and the eccentric point of the lower waist eccentric cam 28 is on the virtual horizontal line passing through the center point of its shaft 30. It is located on the line and ahead of the center point.

The needle 5 enters the cloth W when the eccentric points of both eccentric cams 28, 32 are on the virtual horizontal line and in opposite directions with respect to the center point of each shaft 30, 33. At that time, the needle 5 and the cloth raising rib 12 are in the same positional relationship as normal stitching, so the normal depth stitching is performed.
Also, both eccentric cams 28. , 32 are on the virtual horizontal line and in the same direction with respect to the center point of each axis 30, 33, the needle 5 enters the cloth W. Since the needle relief stepped portion 13 of the cloth raising rib 12 is located at the lower side rather than the upper edge thereof, sewing with a shallow scooping depth is performed.

In other words, when the needle 5 enters the cloth W, the depth of the needle is made shallow once every two times to perform jump stitching.

After the needle 5 has scooped up the cloth W, the cloth raising rib 12 positions the needle release step 13 of the cloth raising rib 12 below the needle 5 by the rotation of both eccentric cams 28 and 32, and the looper (
Needless to say, this is done so as not to obstruct the needle 5 from further entering the cloth W to meet the cloth W (not shown).

Note that it is of course possible to fix the switching pin 39 to the swinging rod 29 so as to project laterally.

In view of the above, according to this invention, the switching plate is used to switch between normal stitching and jump stitching, and during normal sewing, even if the upper eccentric cam is rotating, the swinging rod is swung by the upper eccentric cam. Unlike the conventional method, there is no need for a fixed position stopping device to stop the upper eccentric cam in a fixed position, and there is no need to stop the rotation of the upper eccentric cam. There is no need for a clutch device.

[Brief explanation of the drawing]

The drawings show an embodiment of this invention, in which Fig. 1 is a vertical cross-sectional view showing the state during normal sewing, and Fig. 2 is a longitudinal sectional view showing the state during normal sewing.
FIG. 3 is an enlarged perspective view of the switching plate. 1... Machine frame, 12... Fabric lifting rib, 1
3...Needle relief stepped portion, 25...Rocking rod, 28...Lower eccentric cam, 32...Upper eccentric cam, 39... ...Switching pin, 44...
...Switching plate, 45...Circular hole, 45a...
...Normal seam section, 45b...Jump stitch section.

Claims (1)

[Scope of Claim for Utility Model Registration] 1. Ordinary stitching is performed by swinging the swinging rod for swinging the cloth raising rib with the lower cam, and jump stitching is performed by swinging the swinging rod with the upper and lower gums of the set. In the blind stitch sewing machine, a switching pin is provided in the upper part of the swinging rod in a horizontally protruding manner, and the switching pin is fitted into an arc-shaped guide portion of a switching plate pivotably mounted on the machine frame. and the arc-shaped guide portion has a normal stitch portion and a jump stitch portion,
The normal sewing part is shaped to fix the switching pin so that it does not move in the front and back direction at a position where the swinging rod does not come into contact with the upper cam, and the jump sewing part allows the switching pin to move.
A blind stitch sewing machine whose shape allows the swinging rod to be freely moved by the upper cam. 2. The blind stitch sewing machine according to claim 1, wherein the switching pin is slidable on a swinging rod.