JPH0793996B2 - Method and device for preventing hitch-stitching of eight-way feed sewing machine - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hitch prevention method and apparatus for a eight-way feed sewing machine that prevents hitch stitches in all cloth feed directions.

[Conventional technology]

In sewing a sewing machine, it is required that the stitches to be formed be aligned in the same direction so that the finish of the stitch is beautiful.

The shape of the seam depends on the relationship between the needle and the upper thread 61 and the lower thread 62.
(S)) and hitch stitches (hereinafter referred to as "HS") shown in FIG.

For example, as shown in Fig. 13, when viewed from the direction of the arrow (face side of the sewing machine), showing areas A, B, C, D, the DB type vertical full rotation, which is most often used in industrial lockstitch sewing machines, is shown. For a kettle,
Areas A and D become HS, and areas B and C become PS (however, the vicinity of each boundary is unstable in a mixed area). In the case of the DP type vertical full-rotation hook that scoops the upper thread, which is often used in sewing machines, in some directions (depending on the hook mounting position, for example, at the same mounting position as the DB type, A And PS / HS mixed area near the boundary of Area B and all)
Although PS is shown in FIG. 13, 5 is a needle bar, 30 is a needle plate, 41 is a presser foot, 42 is a cloth feed plate, and 50 is a needle.

FIG. 7 is a plan view showing the feeding direction of the lower thread 62 (same as the feeding direction of the cloth) with respect to the DP type vertical full-rotation hook (hereinafter referred to as “hook”) 51, FIG. 8 (a), (b) and FIG. 9 (a), (b)
Is a plan view and a front view (as viewed from the side of the sewing machine) showing how the upper thread 61 is entangled with the needle 50, FIG. 10 and FIG.
FIG. 11 shows a PS area, a PS / HS mixed area, and an HS area by the upper thread 61 (entangled state) and the lower thread 62 (cloth feed direction) with respect to the needle 50.

Reference numeral 31 in the drawing is a needle hole provided in the needle plate 30, and is a plan view of each sewing machine showing that HS or PS can be obtained depending on the winding direction of the needle thread around the needle when feeding in the hook shaft direction. There is.

In FIG. 8 (a), the feeding direction of the needle thread 61 is indicated by the arrow A,
When changing from B, C, D, E, the upper thread in the direction of the arrow E
61 is clockwise with respect to the needle 50 as shown in FIG. 9 (b), but as shown in FIG. 9 (a), the feeding direction of the needle thread 61 is indicated by arrows I, H, T, J, H. , The needle thread 61 in the direction of the arrow E turns counterclockwise with respect to the needle 50 as shown in FIG. That is, there are two ways of turning in the direction of arrow E, clockwise and counterclockwise.

This is shown in relation to the feeding direction of the lower thread 62, as shown in FIG.
As shown in Fig. 11, Fig. 10 shows that the bobbin thread 62 feed direction (solid line in the feed direction of the cloth fed by the cloth feeding device that moves the cloth in the XY directions according to the sewing data) is from arrow A. PS is between arrow B, but PS is in the area between arrow B and C.
HS and HS are mixed, and HS is shown between the arrow C and the arrow A. FIG. 11 shows HS between arrow A and arrow B, PS and HS are mixed in the area between arrow B and arrow C, and PS between arrow C and arrow A. There is.

Actually, the area between arrows A and B is as shown in FIG. 10, and the area between arrows A and C is as shown in FIG.
It is PS, and the area from arrow B to arrow C is a mixed area of PS and HS, and in some cases, it is an area where HS occurs.

In order to prevent the occurrence of such HS, a cam groove is provided on the needle bar that holds the needle in a sewing machine that is conventionally HS when performing reverse stitching, and the needle is reciprocally rotated a predetermined angle in conjunction with the vertical movement of the needle. A needle bar rotating mechanism of a sewing machine has been proposed which prevents the generation of HS by doing so (see JP-A-54-126157).

[Problems to be Solved by the Invention]

However, in such a conventional HS prevention method, the needle is always rotated regardless of whether the sewing machine is forward stitching or backward stitching. There is a problem that it becomes as shown in Fig. 11, and when turned clockwise, it becomes as shown in Fig. 10.

The present invention has been made in view of the above points, and an object of the present invention is to provide a HS prevention method and device for an eight-way feed sewing machine that can always obtain PS in any case.

[Means for Solving the Problems]

In order to achieve the above object, the present invention is a hitch prevention method for an eight-way feed sewing machine having a perforated stitch area and a perforated stitch / hitch stitch mixed area corresponding to the cloth feeding direction, wherein the cloth feeding direction is When it enters the perforated stitch / hitch stitch mixed area, it is detected and the needle is reciprocally rotated a predetermined angle in conjunction with its vertical movement, or air is blown onto the needle thread and the direction of the lower thread is fed. The outlet so that it does not cross the needle.

Further, the HS prevention device is a device for carrying out the above method, and relates to the cloth feeding device for moving the cloth in the XY directions according to the sewing data and the rotation of the sewing machine main shaft through the needle thread. Incorporating a needle that moves up and down and a bobbin thread, the perfect stitch area and perfect stitch
In a eight-way feed sewing machine that has a hitch-stitch mixed area and is equipped with a DP-type vertical full-rotary hook for scooping the upper thread, the needle bar is moved up and down by the rotation of the upper shaft. Needle bar rotating means for rotating the eclectic / hitch-stitch mixed area or more, needle hole opening / closing means for moving the displacing member so as to displace the lower thread exit position of the needle hole, and the cloth feeding direction is a perffect stitch. .Equipped with means for detecting entry into the hitch-stitch mixed area, when the cloth feed direction enters the perforated stitch / hitch-stitch mixed area, the needle bar is rotated and the exit of the bobbin thread is biased. It was done like this.

[Action]

By doing the above, when the cloth feed direction is in the PS area, the needle bar is not rotated or air is not blown, and the bobbin thread outlet is not offset. You can obtain PS by performing the same operation as.

When the cloth feed direction enters the PS / HS mixed area, the needle bar is reciprocally rotated in conjunction with its vertical movement, or air is blown onto the needle thread, and at the same time, the lower thread outlet is offset and the lower thread By preventing the feed direction from crossing the needle, the PS area can be expanded and the conventional PS / HS mixed area can be changed to the PS area, thus preventing the occurrence of HS.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 7 of the accompanying drawings.

FIG. 1 is a perspective view showing an embodiment of the present invention.

A counterweight 2 is fixed to one end of an upper shaft 1 that is rotatably provided in the arm of a sewing machine, and a needle bar crank 3 is connected to the counterweight 2. The rotary motion is converted into the vertical motion of the needle bar hanger 4.

A needle bar 5 for mounting a needle 50 at its lower end is rotatably loosely fitted to the needle bar holder 4, and the needle bars 5 are integrally held by the guides 6 and 7 so that the needle bar holder 4 is held from above and below. , Vertical motion is applied to the needle bar 5.

On the outer peripheral surface of the needle bar 5, along the axis of the spline groove 5a
Is provided so that the spline nut gear 8 slidably fitted on the outer peripheral portion of the needle bar 5 can be moved in the same direction in the rotational direction. Screw teeth are engraved on the outer peripheral portion of the spline nut gear 8 and are not shown. Make it supported by the machine frame of the sewing machine.

A drive gear 9 having screw teeth that mesh with the spline nut gear 8 is fixed to one end of a needle bar rotating shaft 10, and the needle bar rotating shaft 10 is mounted parallel to the upper shaft 1 on a fixed portion. Needle bar rotation axis
Link one end of link 11 to the other end of 10, and link the other end.
12, connected to one end of rod 14 via bell crank 13,
A bearing portion 14a is formed at the other end of the rod 14, a bush 15 is rotatably fitted in the bearing portion 14a, a long hole 15a is provided at the central portion of the bush 15, and a flat portion 15b is provided at the outer peripheral portion. Long hole 15
The eccentric cam 16 fixed to the upper shaft 1 is loosely fitted to a and the needle bar rotating means for rotating the needle bar 5 by an angle larger than the PS / HS mixed region is formed.

An arm 20 is provided at a position where one end of the bush 15 can be engaged with the flat portion 15b of the bush 15, and the other end is pivotally attached to a fixed portion by a shaft 21 so as to be swingable. A pin 24 is pivotally attached to the plunger 23, and a compression spring 25 is attached to the plunger 23 to urge the plunger 23 in the protruding direction.

Then, by exciting the electromagnetic magnet 22, the plunger 23 is attracted in the direction of arrow D against the compression spring 25,
The lower end of the arm 20 presses against the flat surface portion 15b of the bush 15 so as to prevent its rotation, and these constitute a switching means for switching the needle bar rotating means between an operating state and a non-operating state.

Further, a wire mounting plate 26 is fixedly mounted on the plunger 23, one end of the wire 32 is fixed to the wire mounting plate 26, and the other end is guided to the lower side of the needle plate 30 by a cover 33 fixed to the machine frame.

FIG. 2 shows the needle plate 30 with a part cut away. The needle plate 30 is provided with a needle hole 31 and is swung between a position where the needle hole 31 is fully opened and a position where it is partially closed. An opening / closing lever 34, which is a possible displacement member, is pivotally attached to the back surface of the needle plate 30 by a step screw 35, the end portion of the wire 32 is connected to the tip bending portion 34a of the opening / closing lever 34, and the bending portion 34a is covered. A needle spring opening / closing means is configured by engaging a compression spring 36 with 33 and urging the opening / closing lever 34 in the clockwise direction in the figure.

Although not shown, a hook shaft of a DP type vertical full rotation hook 51 (Fig. 7) is provided in parallel with the needle plate 30 below the needle hole 31, and its outer hook is lifted by a well-known rotation transmission mechanism (not shown). The shaft 1 rotates once, that is, the needle bar 5 reciprocates once for two rotations. Then, as shown in FIGS. 3 and 4,
The lower thread outlet 53 of the bobbin case 52 is set to the conventional outlet position 53 ′.
Shift to the right from the position indicated by.

In FIG. 1, 41 is a cloth retainer, and 42 is a cloth feed frame which stretches cloth and moves in a plane in an arbitrary direction.

Next, the operation of this embodiment having the above structure will be described.

The feeding direction of the cloth fixed to the cloth feed frame 42 is shown in FIGS.
As shown in the figure, PS from the direction of arrow B to the direction of arrow C
・ When it comes to the HS mixed area, it is detected by the reference data of the cloth feeding direction input in the storage device in advance, but the processing device detects it by the image captured by the camera that the cloth feeding frame 42 has moved in that direction. Electromagnetic magnet 22
To excite.

As a result, the plunger 23 is attracted in the direction of the arrow D against the urging force of the compression spring 25, the arm 20 is turned clockwise to the state shown in FIG. 1, and its tip end is pressed against the flat surface portion 15b of the bush 15. Then, the rotation of the bush 15 is blocked.

At the same time, since the wire 32 is pulled in the direction of the arrow D, the opening / closing lever 34 resists the compression spring 36 and enters the state shown by the solid line in FIG. 2, and the needle hole 31 is opened.

By rotating the upper shaft 1 in this state, an eccentric cam integrated with this
16 rotates in the long hole 15a of the bush 15, but the bush 15
Since its rotation is blocked by the arm 20, the bush 15 moves up and down while the plane portion 15b and the arm 20 slide.

As a result, the rod 14 integral with the bearing portion 14a loosely fitted in the bush 15 also moves up and down, and the needle bar rotation shaft 10 reciprocally rotates via the bell crank 13 and the links 12 and 11. The reciprocating rotation is transmitted to the needle bar 5 via the drive gear 9 and the spline nut gear 8, and the needle bar 5 reciprocally rotates during its vertical movement.

FIG. 5 is a diagram showing the relationship between the vertical movement and the reciprocating rotary movement of the needle bar 5 having the needle 50 mounted thereon.

As can be seen from the figure, after the needle bar 5 has descended and started to rise, a loop is formed in the needle thread 61 guided to the needle 50, and after a predetermined time from the point P ₁ when the tip of the rotating outer hook enters the loop. in point P ₂ to rotate the needle bar 5 in the arrow E direction of FIG. 1,
The maximum twisting angle α is reached during the time point P ₃ when the needle bar 5 starts to descend from the raised point P.

After that, the needle bar 5 is reversely rotated at a time point P ₄ during the descending operation, and is returned to the old position at a time point P ₅ when the vicinity of the descending end is reached.

In this way, when the needle 50 is rotated in the arrow E direction by a predetermined angle α equal to or larger than the PS / HS mixed region, the needle thread 61a is entangled with the needle 50 as shown in FIG. Further, the bobbin thread coming out of the bobbin case 52 is located at the left side position as shown in FIG. 6 when the bobbin case 52 shown in FIG. 4 is in the state shown in FIG.

Therefore, since the needle 50 does not cross the needle 50 until the feeding direction of the lower thread 62 shown in FIG. 6 reaches the arrow C direction, a wide range from the arrow A direction to the arrow C direction, that is, the conventional PS region. The PS area is the area that includes the PS / HS mixed area. Furthermore, in the HS area, the arrow D indicates that the feed direction exceeds the needle 50.
Between C and D, PS and HS are mixed areas.

Therefore, when the cloth feeding direction goes from the arrow C to the arrow D, the detection means (not shown in FIG. 1) detects this and releases the excitation of the electromagnetic magnet 22.

As a result, the plunger 23 projects by the urging force of the compression spring 36, and the arm 20 rotates counterclockwise and retracts from the outer peripheral portion of the bush 15. In this state, the bush 15 can freely rotate in the bearing portion 14a, and when the upper shaft 1 and the eccentric cam 16 integrated with the upper shaft 1 rotate, the bush 15 moves accordingly.
The ring 15 idles in the bearing 14a, the link 14 becomes stationary, and the needle bar 5 is kept non-rotating.

At the same time, since the wire 32 relaxes, the opening / closing lever 34 shown in FIG. 2 rotates clockwise by the urging force of the compression spring 36, and the opening / closing lever 34 partially closes the needle hole 31 as shown by the phantom line in FIG. To do.

As a result, the bobbin thread 62 pulled out from the bobbin case 52 is biased to the left side, and is in a position almost equivalent to the conventional outlet 53 'shown in FIG. 4, and as shown in FIG. The area between C is the PS area as in the conventional case.

In the embodiment described above, as a method of restricting the needle hole outlet of the lower thread 62, the lower thread outlet of the bobbin case 52 is offset from the conventional one, and this is restricted by the displacement of the opening / closing lever 34. The displacement of the open / close lever 34 can be adjusted and regulated while the lower thread outlet of the conventional type is used as it is. Further, in the above embodiment, the needle bar rotating means for reciprocally rotating the needle bar by a predetermined angle in association with the vertical movement of the needle bar due to the rotation of the upper shaft is provided, but between the point before the point P and the point P ₄ in FIG. Air may be blown onto the needle thread to drop the needle thread in the PS direction.

[Advantages of the Invention] As described above, according to the present invention, the cloth feeding direction is
When entering the PS / HS mixed area, interlock the needle with its vertical movement.
Since the needle thread is rotated reciprocally more than the PS / HS mixed area or air is blown onto the needle thread, the outlet of the lower thread is offset so that the feed direction does not go over the needle.
HS can be prevented by changing the mixed area to the PS area.

Further, in the device, the exit position of the bobbin thread can be displaced simply by opening and closing the needle hole by slightly moving the displacement member in accordance with the cloth feeding direction. It is possible to speed up.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention, FIG. 2 is a perspective view showing the needle hole opening / closing mechanism by cutting out a part of the needle plate, and FIG. 3 is a bobbin case and a needle hole. 4 is a plan view showing the bobbin case and the bobbin thread exit position in comparison with the conventional one, and FIG. 5 is a diagram showing the relationship between the vertical movement of the needle bar and the rotation angle. 6 is a diagram showing the feeding directions of the upper thread and the lower thread with respect to the needle when the needle hole outlet of the lower thread is displaced, and FIG. 7 is a plan view showing the feeding directions of the shuttle and the lower thread, and FIG. ), (B) and FIGS. 9 (a), (b) are plan and front views showing how the needle and the upper thread are entangled, and FIGS. 10 and 11 are how the upper thread is entangled with the needle. Explanatory drawing showing PS area, HS area, and PS / HS mixed area, which are determined by the feeding direction of cloth. Figures 12 (a) and 12 (b) show PS and HS seams. FIG. 13 is an explanatory diagram showing each of them, and FIG. 13 is an explanatory diagram showing the positional relationship of the A, B, C, and D regions as seen from the surface side of the sewing machine. 1 …… Upper shaft, 5 …… Needle bar 5a …… Spline groove 8 …… Spline nut gear 10 …… Needle bar rotating shaft, 14 …… Rod 15 …… Bush, 16 …… Eccentric cam 20 …… Arm, 22 ...... Electromagnetic magnet 23 ...... Plunger, 30 ...... Needle plate 31 ...... Needle hole, 32 ...... Wire 34 ...... Open / close lever, 50 ...... Needle 51 ...... Hook, 52 ...... Bobbin case 61 ...... Upper thread, 62 …… Bottom thread

Claims (2)

[Claims] 1. A method for preventing hitch stitches of an eight-way feed sewing machine having a perforated stitch area and a perforated stitch / hitch stitch mixed area corresponding to the cloth feeding direction, wherein the cloth feeding direction is the perforated stitch. When it enters the hitch-stitch mixed area, it is detected and the needle is reciprocally rotated by a predetermined angle in conjunction with its vertical movement, or the needle thread is blown with air and the bobbin thread feed direction does not cross the needle. A method for preventing hitch-stitching of an eight-way feed sewing machine, which is characterized in that the outlets of the eight-way feed machines are offset. 2. A cloth feed device for moving the cloth in the XY directions according to the sewing data, a needle for inserting an upper thread and moving up and down in association with the rotation of a sewing machine main shaft, and a lower thread for accommodating the needle in the cloth feed direction. Correspondingly, the perfect stitch area and the perfect stitch area
In an eight-way feed sewing machine having a hitch-stitch mixed area and equipped with a DP type vertical full rotary hook for scooping the upper thread, the needle bar is moved up and down by the rotation of an upper shaft. Needle bar rotating means for rotating the eclectic / hitch-stitch mixed area or more, needle hole opening / closing means for moving the displacing member so as to displace the lower thread exit position of the needle hole, and the cloth feeding direction is a perffect stitch. .Equipped with means for detecting entry into the hitch-stitch mixed area, when the cloth feed direction enters the perforated stitch / hitch-stitch mixed area, the needle bar is rotated and the exit of the bobbin thread is biased. The hitch-stitch prevention device for an eight-way feed sewing machine characterized by the above.