JPS6038477Y2 - Lower thread tensioning device for lockstitch sewing machine equipped with bobbin thread replenishment device - Google Patents

Description

[Detailed Description of the Invention] Technical Field This invention relates to a lockstitch sewing machine equipped with a device for replenishing thread to a bobbin, and in particular, to a device for applying lower thread tension to impart tension to the thread being paid out from the hobbin. It is related to the device.

Prior Art Conventionally, in a lockstitch sewing machine equipped with a bobbin thread replenishing device,
When performing the bobbin thread replenishment operation, the fixed side cavity of the needle thread ring captured by the thread ring catcher is guided to the bobbin in the bobbin case via the bobbin thread tensioning device on the bobbin case, and then
The stationary side cavity is introduced between the lower surface of the bobbin case and the thread ring catcher, and by rotating the thread ring catcher and the bobbin in this state, the bobbin is replenished with needle thread.

After the bobbin thread replenishment operation is completed, one end of the thread wound around the bobbin is placed between the bottom surface of the bobbin case and the thread loop catcher via the bobbin thread tensioning device, and the thread is then sewn as usual. An eye forming operation is performed.

In a sewing machine equipped with this bobbin thread replenishment device, when setting a bobbin pre-wound with threads of different colors or thicknesses into the bobbin case, store the bobbin in the bobbin case, and then is inserted between the flange of the bobbin case and the lace portion of the thread wheel catcher, and placed between the lower surface of the bobbin case and the thread ring catcher, and the bobbin thread is introduced into the bobbin thread tension applying device. It was necessary to set it in a tensioned state.

Therefore, in this conventional configuration, the operation of threading when replacing the bobbin is complicated, and there is a risk that the thread may be routed in the wrong direction.

Purpose This invention was made to eliminate the above-mentioned defects, and the purpose is to make the lead-out path of bobbin thread that accompanies bobbin replacement different from the lead-out path of bobbin thread that accompanies bobbin thread replenishment operation. It is possible to correct the difference in thread passing resistance due to different thread passing paths, and it is also possible to simplify the operation of threading the bobbin thread when replacing the bobbin, and to maintain stability in the bobbin thread. An object of the present invention is to provide a bobbin thread tension applying device for a lockstitch sewing machine, which is equipped with a bobbin thread replenishing device capable of applying a certain tension.

Embodiment An embodiment embodying the present invention will be described below with reference to the drawings. As shown in FIG. ) A support tube 4 is fixed to a bracket 3 in the bed portion a below the support tube 4, and an operating shaft 6 having a disk 5 is inserted into the support tube 4 so as to be vertically movable and rotatable.

Projections 5a and 5b are provided on the outer periphery and upper surface of the disc 5.

The inner peripheral surface of the thread ring catcher 7 is formed with a locking groove 10 in which the lace portion 8, the thread ring catcher 9, and the protrusion 5a on the outer periphery of the disk 5 are engaged, and the lower surface of the thread ring catcher 7 is formed with a locking groove 10. The support tube 4
A screw gear 11 is formed in a protruding manner to be inserted into the support cylinder 4 and rotate around the support cylinder 4 thereof.

As the lower shaft (not shown) rotates, the screw gear (not shown) on the lower shaft and the screw gear 1
1, the thread ring catcher 7 is rotated in the counterclockwise direction as shown in FIGS. The actuating shaft 6 is rotated together with the thread ring catcher 7 through the actuating shaft 6.

A hobbin case 13 having a substantially cylindrical shape and having a flange portion 13a and a needle drop groove 13b on the outer periphery is housed in the thread ring catcher 7, and the flange portion 13a is engaged with the lace portion 8 from above. .

A thread carrying bobbin 14 is housed in the bobbin case 13, and its lower flange 15 is formed with a recess 15a into which the protrusion 5b on the disc 5 can enter, and the upper flange 16 is formed with a recess 16a and a bobbin A slit 16b for introducing the yarn into each of the slits 14 is formed.

As shown in FIGS. 1a and 1b and 2 and 3, a lever storage portion 1 is provided on the flange portion 13a of the bobbin case 13.
7a and the electric tone plate housing part 17b are formed adjacent to each other, and a communication groove 19 communicating with the lever housing part 17a and a cutout part 18 continuous with the electric tone plate housing part 17b are formed, respectively.

An arcuate control member 20 is rotatably supported at the center of the lever housing portion 17a so that one end thereof is located above the power control board housing portion 17b.

A protruding piece 21 for opening and closing the notch 18 is formed at one end of the control member 20, and a hanging piece 21a is bent on the protruding piece 21, and the communicating groove is formed at the other end. 19 through the upper and lower flanges 16.15 of the bobbin 14
A detection section 23 that can be inserted between the two is bent.

A compression spring 24 is interposed between the control member 20 and the side wall of the lever storage portion 17a near the detection portion 23.

During normal sewing operation, the detection section 23 is locked to the inner wall side of the bobbin case 13 by the spring force of the compression spring 24, and the cutout section 18 is closed by the projection piece 21 and the hanging piece 21a, so that the control member 20 is placed in the first position shown in FIG. 1a.

Further, when replenishing the bobbin thread, the control member 20 is rotated counterclockwise in FIG.
5, and the projecting piece 21 and the hanging piece 21
a is retracted, the notch 18 is opened, and the control member 20 is moved to the first position.
It is placed in the second position shown in the figure.

A lower thread tension applying device 25 for applying tension to the thread wound around the bobbin 14 is provided in the electric adjustment board housing portion 17b.

Note that the configuration of this device 25 will be described later.

Three float prevention pieces 29 are screwed onto a support plate 28 fixed on the bracket 3 below the throat plate 2 to prevent the bobbin case 13 from floating during operation of the sewing machine.

Further, on the bracket 3, there are a pair of regulating pieces 30 for alternately engaging the bobbin case 13 and regulating its rotation.
A regulating member 30 having a shape a is supported so as to be able to swing in time with the rotation of the thread ring catcher 7.

A rotation shaft 31 is inserted through the right side extension 3a of the bracket 3, and a substantially L-shaped selection member 32 is fixed at its base end to its upper end.

The recess 16 of the bobbin 14 is located at the tip of the selection member 32.
A protrusion 33 that can be entered into the control member 20 is formed, and a thread cutting portion 33a is formed on the lower surface of the protrusion 33, and a thread cutting portion 33a is formed in the center of the selection member 32 that can be engaged with the outer edge of the control member 20. A pin 34 is provided to protrude downward.

The selection member 32 is located between a first position for the stitch forming operation shown in FIG. When the selection member 32 is placed in the first position shown in FIG. 1A, the rotation shaft 31. The operating shaft 6 is moved down via the cam body 35 and the linking member 36, and the operating shaft 6 is placed at the chain line position in the figure, and the connection between the bobbin 14 and the thread ring catcher 7 is released.

Further, when the selection member 32 is placed in the second position shown in FIG. 6 is placed at the solid line position in the figure, the protrusion 5b of the disc 5 enters the recess 15a of the bobbin 14, and the bobbin 14 and the thread ring catcher 7 are connected.

The operating shaft 6 and the slit 16b1 of the bobbin 14
The cut arrow section 18, the control member 20, the selection member 32, and the like constitute a bobbin thread replenishing device.

Next, the configuration of the bobbin thread tension applying device 25 will be explained in detail.

As shown in FIGS. 1a and 1b, FIGS. 3 and 4, a and b, a thread tension plate 37 having an arcuate planar shape is housed in the electric tone plate storage portion 17b, and its base end mounting portion is It is attached to the bobbin case 13 by a screw 38 at 37a.

An L-shaped first thread guide slit 39 that opens upward is formed approximately in the center of the thread tension plate 37, and an arc-shaped first thread guide end 40 is formed at the base end of the L-shaped first thread guide slit 39.

In addition, so as to be located close to the first thread leading end 40,
A notch 41 is formed in the upper edge of the thread tension plate 37.

As shown in FIG. 4a, a bobbin 14 on which a thread having a different color and thickness from the needle thread is wound in advance is placed in a bobbin case 1.
3, one end of the bobbin thread Y wound around the bobbin 14 is inserted into the first thread guide slit 39 from inside the bobbin case 13, and then the thread tension plate 37 is set.
The first thread leading end 40 and the notch 41 on the outer peripheral surface of
and the notch 41.
It is placed on the bobbin case 13 via.

A second thread guide slit 42 that opens toward the notch 18 is formed at the tip of the thread tension plate 37, and an arc-shaped second thread guide end 43 is formed at the base end of the second thread guide slit 42. .

Further, a thread tension plate 37 is provided adjacent to the second thread leading-out end 43.
A stepped portion 44 is formed at the lower edge of the holder.

Then, as shown in FIG. 4, during the bobbin thread replenishment operation, the fixed side cavity Z1 of the needle thread ring Z captured by the thread ring catcher 9 is inserted into the second thread guide slit 42, The slit 42 and the notch 18 of the bobbin case 13
A second thread leading-out path P2 is introduced into the bobbin case 13 through the thread, and the fixed side cavity Z1 connects the second thread leading-out end 43 and the stepped part 44 on the outer peripheral surface of the thread tension plate 37. It passes through the top and is connected to the needle-side crotch part Z2 of the needle thread ring Z between the bottom surface of the bobbin case 13 and the thread ring catcher 7 and through the needle drop groove 13b.

A thread tension spring plate for applying tension to the bobbin thread Y and the needle thread ring 2 is disposed on the outer peripheral surface of the thread tension plate 37 so as to cover the first and second lead-out paths Pi and P2. 45 is attached at its base end with a screw 46, and a positioning piece 47 at its tip is fitted into a round hole 48 of the thread tension plate 37.

An adjusting screw 49 is attached to the thread tension plate 37 in the vicinity of the first thread guide slit 39, the tip of which is in contact with the thread tension spring plate 45, and by rotating the adjusting screw 49, the thread tension spring plate The spring force can be finely adjusted.

Now, when replenishing the bobbin 14 with thread in the lockstitch sewing machine configured as described above, one end of the needle thread is fixed at a predetermined position near the needle N, and then the thread is moved to the first position shown in FIG. 1a. When the selection member 32 disposed at is rotated clockwise in the figure, the protrusion 33 of the selection member 32 enters the recess 16a of the bobbin 14, as shown in FIGS. 1 and 2.
A pin 34 engages the outer edge of the control member 20 and compresses the compression spring 2
The control member 20 is rotated in one direction against the spring force of 4,
The detection portion 23 is connected to the upper and lower flanges 16.15 of the bobbin 14.
At the same time, the projecting piece 21 and the hanging piece 21a retreat, and the notch 18 of the bobbin case 13 is opened.

Further, along with the rotation operation of the selection member 32, the rotation shaft 31.
The operating shaft 6 is moved upward via the cam body 35 and the linking member 36 to the position shown by the solid line in FIG. The container 7 is connected.

When the lower shaft (not shown) is rotated in this state, the thread ring catcher 7 and bobbin 14 are rotated integrally through the screw gear 11, and in synchronization with the rotation of the thread ring catcher 7. The needle N is moved in the vertical direction.

As shown in FIG. 1 and FIG. 4, the needle thread ring Z is captured by the thread ring catcher 9 as the thread ring catcher 7 rotates.
The fixed side armpit part Z1 of the bobbin 14 is introduced into the second thread guide slit 42 and into the bobbin case 13 through the cutout part 18, and the fixed side armpit part Z1 passes through the thread guide 16b. It enters between the upper and lower flanges 16.15.

Further, the fixed side armpit part Z1 is connected to the second thread leading-out end 4.
3. It passes between the stepped portion 44, the lower surface of the bobbin case 13, and the bottom surface of the thread ring catcher 7, and is connected to the needle side mounting portion Z2 of the needle thread ring Z via the needle drop groove 13b.

Note that the fixed side armpit part Z1 is the second thread guide slit 42.
When the thread reaches the second thread leading-out end 43 along The fitting part Z1 enters between the tension plate 37 and the second lead-out path P.
2, it is held between the thread tension spring plate 45 and the thread tension plate 37.

Then, as the thread ring catcher 7 and the bobbin 14 continue to rotate, the needle thread is applied with tension by the thread tension spring plate 45 and reaches the lower surface of the bobbin case 13 and the second thread outlet end 43.
The hobbin 14 is wound and replenished through the hobbin 14.

When this needle thread is sufficiently wound around the hobbin 14, the detection portion 23 of the control member 20 engages with the wound thread, and as the winding diameter of the thread further increases, the control member 20 is rotated back, The selection member 32 is rotated back via the pin 34.

As a result, the operating shaft 6 is moved down through the rotation shaft 31 and the like to the position shown by the chain line in FIG. Then, the bobbin thread replenishment operation ends.

Further, in this embodiment, after the first needle thread ring Z is formed, a predetermined needle bar release mechanism (not shown) is activated to stop the vertical movement of the needle N. The fixed side armpit part Z1 of the thread ring Z enters between the recess 16a of the bobbin 14 and the protrusion 33 of the selection member 32, and the thread cutting part 33a
As a result, the fixed side armpit portion z1 is cut.

When performing the stitch forming operation using the thread replenished to the bobbin 14 as described above, as is clear from FIG.
After cutting the needle side mounting part Z2 of the needle thread ring Z and placing the thread end on the bobbin case 13, the selection member 32 and the control member 2o are placed in the first position shown in FIG. 1a. However, when the thread ring catcher 7 and the needle N are operated with the bobbin 14 and the thread ring catcher 7 disconnected from each other, the protruding piece 21 and the hanging piece 21a open the notch as shown in FIG. 1a. Since the portion 18 is closed, the needle thread ring Z passes smoothly through the bobbin case 13 as the thread ring catcher 7 rotates.

Further, the thread end of the thread wound around the bobbin 14 is locked by the needle thread ring Z, and the thread wound around the bobbin 14 is pulled up based on the needle thread ring picking up action of a thread take-up (not shown). The thread is let out from the second thread lead-out end 43.

Then, this bobbin thread passes through the lower surface of the bobbin case 13 on the second lead-out path P2 while being applied with an appropriate tension by the thread tension spring plate 45.

On the other hand, when performing a stitch forming operation using a bobbin 14 pre-wound with a thread different in color and thickness from the needle thread, the bobbin 14 is After storing it in the bobbin case 13, as shown in FIG. 4a, one end of the bobbin thread Y is inserted into the first thread guide slit 39,
When the bobbin thread Y enters the first thread outlet end 40, the tip of the thread tension spring plate 45 is displaced outward against its own spring force, and the bobbin thread Y is moved to the thread tension spring plate 45. and the thread tension plate 37.

Then, when this bobbin thread Y is passed between the first thread lead-out end 40 and the notch 41, the bobbin thread Y passes between the thread tension spring plate 45 and the thread tension plate 37 on the first thread lead-out path P1. It is held between the two.

Thereafter, by placing one end of the bobbin thread Y on the bobbin case 13, the threading work can be easily accomplished in a short time.

Therefore, when the thread ring catcher 7 and the needle N are operated in this state, the needle thread ring Z passes through the bobbin case 13 smoothly.
The bobbin thread Y is locked by the needle thread ring Z, and the bobbin thread Y is let out from the first thread outlet end 40 based on the needle thread ring picking up action of the thread take-up.

Then, this bobbin thread Y passes over the bobbin case 13 on the first lead-out path P1 while being applied with an appropriate tension by the thread tension spring plate 45.

Further, in this embodiment, as shown in FIGS. 4a and 4b, the thread tension plate 37 has mutually different first and second lead-out paths PI
, P2 are arranged and the stitch forming operation is performed continuously during and after the bobbin thread replenishment operation, and
When performing a new seam forming operation by replacing the
Since it is possible to cause a slight difference in the tension applied to each thread, the difference in thread passing resistance based on the different thread passing paths depending on whether or not the thread passes through the bottom surface of the bobbin case 13 can be calculated by the difference in thread tension. can be corrected using

That is, in this embodiment, the thread is attached to the bobbin case 13.
It has been confirmed through experiments that the thread passing resistance is greater when the thread passes through the upper surface than when it passes through the lower surface of the bobbin case 13.

Therefore, the first and second derivation paths P1 as described above,
By setting P2, a larger tension can be applied to the yarn passing through the second lead-out route P2 than to the thread passing through the first lead-out route P1, and the difference in passage resistance can be corrected.

Effects As detailed above, this invention fixes to the bobbin case a thread tension plate in which a pair of thread guide slits having thread leading-out ends adjacent to each other are formed, and the thread tension plate has threads extending from each thread leading-out end to the bobbin case. Since a single thread tension spring plate is provided that cooperates with the thread tension plate to apply different tensions to the bobbin thread being paid out, the bobbin thread lead-out path when replacing the bobbin and the bobbin thread replenishment operation when the bobbin thread is refilled can be easily adjusted. The lead-out route can be made different, and the difference in thread passing resistance based on different thread passing routes can be corrected, and the operation for threading the bobbin thread when replacing the bobbin can be simplified. It has the excellent effect of being able to impart stable tension to the bobbin thread.

[Brief explanation of the drawing]

Figure 1a shows a thread loop catcher 7 of a sewing machine that embodies this idea.
FIG. 1 is a plan view of the thread loop catcher 7 during the bobbin thread replenishment operation; FIG.
The figure is a sectional view taken along the line ■-■ of Figure 1, and Figure 3 is a cross-sectional view of Figure 1.
Figure 4a is a partial sectional view taken along the line ■-■ in Figure 4. Figure 4a is an enlarged front view showing the thread passing path and lower thread tension applying device during bobbin replacement. Figure 4 is the thread passing route during bobbin thread replenishment operation. FIG. 3 is an enlarged front view showing the lower thread tension applying device. Operating shaft 6, thread ring catcher 7, thread ring catcher 9, bobbin case 13, thread carrying bobbin 14, slit 16b, notch 1
8, control member 20, selection member 32 (said 6, 16b, 1
8, 20, 32, etc., constitute a bobbin thread replenishing device), thread tension plate 37, first thread guide slit 39, first thread leading end 40, second thread guide slit 42, second Thread lead-out end 43, thread tension spring plate 45, first lead-out path P1
, second derivation path P2, needle N0

Claims (1)

[Claims for Utility Model Registration] A thread ring catcher 7 having a thread ring catcher 9 and rotatable in synchronization with the longitudinal reciprocating movement of the needle N, and a bobbin supported within the thread ring catcher 7. a case 13, a thread carrying hobbin 14 rotatable in its bobbin case 13, and a device 6, 16b, 18, 20 for replenishing the bobbin thread from the thread carried by said needle N on its bobbin 14;
32, etc.), and a pair of thread guide slits 39.4 fixed to the bobbin case 13 and having mutually adjacent thread lead-out ends 40.43.
2 is formed, and the thread tension plate 37 is fixed so as to cover the thread tension plate 37, and cooperates with the thread tension plate 37 to apply different tensions to the bobbin threads let out from each of the thread leading-out ends 40 and 43. A single thread tension spring plate 45 is provided to make the bobbin thread lead-out path P1 when the bobbin 14 is replaced different from the bobbin thread lead-out path P2 when the bobbin thread is replenished. A lower thread tension applying device.