JPH09135983A - Quick thread tension switching device for sewing machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce operation time for switching a sewing condition, by driving a thread hanging part mounted between a second thread tension controller to give tension to the thread guided into a lower looper and the lower looper by operation of an operation part and making the second thread tension controller stitchable to action and no-action. SOLUTION: When a sewing condition, for instance edge stitching, is selected by a sewing selection means responding to desired sewing, a looper thread hanging part 69 is moved toward Y direction through a switching connection bar 55 to the dot line position, and the upper contact part of a transmission bar 53 is moved upward through the other end of a switching lever 52. Further, the end part of a swing lever 34 is moved toward X direction by a driving part 59 through an action lever 58 and an operation lever 33 and is brought in contact with a dent part of a cam plate 42. Thus the cam plate can be rotated front/back to rotate the action part of an action lever 45 to switch a thread tension pan 49 of the second thread tension controller 46 to perform switching.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thread tension rapid switching device for a sewing machine.

[0002]

2. Description of the Related Art When changing the thread tension of a conventional overedge stitch sewing machine, especially when changing from the overlock stitching state to the winding stitch state, the conditions for adjusting the thread tension of the lower looper are drastically changed. It took time. As shown in FIG. 1, the thread tension adjusting devices 1, 2, 3, respectively for the threads introduced into the sewing machine needle and the lower looper and the upper looper, respectively.
4 is provided, the thread tension is adjusted by rotating the respective operation dials 5, 6, 7, 8 of the thread tension adjusting device with fingertips before sewing. Therefore, overlock stitching in the overlock stitch sewing machine (the construction of the sewing thread is as shown in FIGS. 2 and 3, and FIG. 2 is a configuration diagram with three threads, FIG.
Shows the tension of the lower looper thread at the time of two threads) and the winding sewing (the composition of the sewing thread is shown in FIGS. 4 and 5, FIG. 4 is the configuration with three threads, and FIG. (It is composed of main thread)
Since it is significantly different from the tension of the lower looper thread at the time, it takes time to operate the thread tension dial to obtain an appropriate tension at the time of switching from overedging to winding sewing. In each figure, T1 is a needle thread, T2 is a lower looper thread, T3 is an upper looper thread, and when sewing with two threads, an upper looper thread T3.
Is unnecessary.

[0003]

DISCLOSURE OF THE INVENTION The present invention is directed to overlock sewing machines for switching overlock stitches from a normal sewing state to a winding stitch state (the same number of threads) or vice versa. The thread tension of the lower looper thread, that is, the thread tension when switching from 3 threads to 2 threads in the normal sewing state of sewing, or vice versa, is 100 g in the normal sewing of the overlock stitch, 25 g in the winding stitch, and the edge is Even in the normal sewing of overlock stitch, it is necessary to adjust or switch to 25 g for 3 threads and 100 g for 2 threads respectively, and dial operation at the time of switching requires time, and it is a long time for the operator to shorten the operation time. It was a matter of concern.

[0004]

The present invention relates to a thread tension changing device for a lower looper thread in an overlock stitch sewing machine, and a thread tension adjusting device capable of continuously adjusting the thread tension and a second thread tension applying apparatus. And a thread tension device of
Is provided in the thread introduction path from the thread tension device to the lower looper, the thread hooking portion capable of moving the arrangement position is provided, and the movement of the thread hooking portion and the tensioning of the second thread tension device are performed. By providing a drive unit that simultaneously performs switching and providing an operation unit that initially drives the drive unit, adjustment of the second thread tension device and switching of the position of the thread hooking unit are performed only by operating the operation unit. It is possible to perform and quickly.

[0005]

According to the present invention, a needle bar having a sewing machine frame vertically movably supported and having a sewing needle attached to a lower end thereof, a lower looper oscillating in synchronization with a vertical movement of the needle bar, and a vertical movement of the needle bar. And an overlock stitch sewing machine including an upper looper that swings in synchronization with the swing of the lower looper, and applies tension to a plurality of threads guided to the needle, the lower looper, and the upper looper, respectively. A plurality of first thread tension devices are provided, and a second thread tension device capable of further applying tension to the yarn introduced into the lower looper is provided, and the second thread tension device and the lower looper are provided. By providing a thread hooking portion whose disposition position can be changed in the thread introducing path between them, and by providing a drive portion that acts on the thread hooking portion and the second thread tension device by operating the sewing method selecting means, Quick adjustment of the thread tension device when changing the sewing method Tighten it becomes easier with occupied become of it and is characterized in.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of one embodiment of the present invention will be described below with reference to the drawings. A drive shaft (not shown) rotatably supported on the sewing machine frame 11, a needle bar 12 that is vertically moved in association with the rotation of the drive shaft, and a needle 13 that is attached to the tip of the needle bar. There is provided a lower looper 14 and an upper looper 15 (see FIG. 6) which cooperate with each other and are caused to swing.

The needle 13, the lower looper 14, and the upper looper 15 are respectively supplied with yarns T1, T2, T3, etc. introduced from a plurality of yarn spools supported by a yarn stand through their respective paths. . A thread stand 16 for supporting the threads is provided on the back side of the sewing machine frame 11, and the threads T1, T2, T3 ...
Passes through each guide of the thread guide portion 17 arranged above, then passes through the thread guide portion 18, passes through the slit portions 19 provided on the front wall of the sewing machine frame, and the first thread tension device 1 2,
Guided to 3, 4.

Although a plurality of the first thread tension devices are provided, the respective structures are the same and are as follows.
That is, a pair of thread tension discs pressed against the thread tension shaft fixed to the machine frame by a thread tension spring and pressed against the sewing machine frame, and the thread tension disc which is rotated on the thread tension axis and moved in the axial direction. Operation dials 5, 6 for controlling the acting force of the tone spring,
It is composed of 7 and 8.

The threads T1, T2, T3 ... Pass through the slit portions 19 ... And between the pair of thread tension discs in the first thread tension devices 1, 2, 3 ... And an appropriate tension is applied. The lower looper thread T2 and the upper looper thread T3 pass through the guide grooves 57, 57 of the thread guide 20 arranged below the front wall of the sewing machine frame 11, and are provided for the respective threads T2, T3. It is guided to each thread hole portion of the lower looper 14 and the upper looper 15 via the thread hooking portion. FIG. 6 shows a state where the yarns T2 and T3 are guided to each looper with the looper cover 21 opened.

The mechanism base 31 of the thread tension changeover device 30 is detachably screwed to the inside of the front wall of the machine frame 11 of the sewing machine, and the mechanism lever 31 is attached to the short shaft 32 at the upper end of the mechanism base.
The lower end of the operation lever 33 connecting 8 is pivotally attached,
One end of a swing lever 34, which is swingable in the left and right directions, is pivotally attached to an intermediate portion of the operation lever, and a cam contact shaft 36 having a contact portion 35 is provided at the other end of the swing lever. Has been.

A cam support plate 3 is attached to a support shaft 38 fixed to a support portion 37 which is vertically bent under the mechanism table 31.
A lower end 40 of the cam support plate is pivotally attached so that the cam 9 can rotate, and a first recess 41 is provided at the upper end of the cam support plate 39.
There is provided a cam plate 42 having a flat surface on which the cam plate 42 is attached to the cam support plate 39 by the action of a spring 43 mounted on the cam support plate 39.
6 is constantly pressed against the contact portion 35, and an action lever 45 forming an action portion 44 whose end is horizontally bent in an L shape is fixed at an appropriate position in the middle of the cam support plate 39. (See Figures 8, 9, 10, 11, and 12).

A second thread tensioning device 46 is provided inside the thread guide 20, and the second thread tensioning device is mounted on a support plate 47 fixed to the base of the thread guide 20. Part 48
And a thread tension disc 49 mounted on the shaft portion and a spring 50.
And a pressure contact portion 51 obtained by bending a part of the support plate 47 (see FIG. 7).

Further, the thread guide 20 has two guide grooves 5
7 and 57 are formed, and one guide groove guides the introduced thread between the thread tension disc 49 and the press contact portion 51.

Between the pressure contact portion 51 supported by the second thread tension device 46 and the thread tension disc 49, the action portion 44 of the action lever 45 of the thread tension switching device 30 is arranged to be exposed. Has been done.

In the thread tension switching device 30, one end of a switching lever 52 is pivotally mounted on a shaft portion of the operation lever 33 whose lower end is pivotally mounted on the mechanism base 31, and further, an appropriate position of the switching lever. One end of the transmission rod 53 is pivotally attached to the transmission rod 53, the other end of the transmission rod is connected to the end of the swing lever 34 by the cam contact shaft 36, and the other end of the switching lever 52. A lower looper thread hooking portion 66 and a switching connecting rod 55 which are movable in the up-down direction (Y direction) of the arm machine frame via a sliding guide piece 54 are provided.
A second recess 56 is further formed on the cam plate 42 at the upper end of the cam support plate 39.

A plunger of a first drive portion (for example, a solenoid) 59 is connected to the other end of the operating lever 58, and a second drive portion (for example, a solenoid) 60 is connected to the other end of the switching connection rod 55. Plunger is connected (see Figure 11).

A sewing method selecting means 61 is provided at an appropriate position on the front wall surface portion of the sewing machine frame 11. According to the combination of the number of threads and the sewing
Individual operating parts are provided. The first selection operation section 62 is an operation section for performing a normal sewing operation of overlock stitching with two threads, and the second selection operation section 63 is an operation section for performing a winding stitch with two threads. The third selection operation unit 64 is an operation unit for performing normal sewing of overlock stitching with three threads, and the fourth selection operation unit 65 is an operation unit for performing winding sewing with three threads ( See FIGS. 6 and 13.).

Each operation section 62 of the sewing method selecting means 61,
Reference numerals 63, 64 and 65 are connected to a CPU (central processing unit) 66 of a microcomputer built in the sewing machine frame 11, and the operation of each operation section is transmitted to each solenoid drive circuit 67 and 68 connected to the CPU 66. , And the second driving unit 60 and the first driving unit 59 which are respectively connected.
(See FIG. 13).

Since the present invention is constructed as described above,
When an appropriate operation section of the sewing method selection means 61 is operated in accordance with a desired sewing method, for example, when the overedging operation using three threads is performed, the selection operation section 64 is operated, and the second drive section 60 is operated. The lower looper thread hooking portion 66 is moved to the position of the upper dotted line in the Y direction shown in FIG. 11 through the switching connecting rod 55 so as to correspond to the sewing of three threads and four threads, and the other of the switching lever 52. The contact portion 35 at the upper end of the transmission rod 53 is moved upwards via the end, and is further supported by the first drive portion 59 on the end portion of the swing lever 34 via the actuating lever 58 and the operating lever 33. By moving the contact portion 35 in the X direction in FIG. 11 and moving it to the left, the contact portion 35 is brought into contact with the second recessed portion 56 of the cam plate 42.

When the contact portion 35 comes into contact with the recessed portions 41 and 56 of the cam plate 42, the cam plate rotates forward with the support shaft 38 at the lower end as a fulcrum by the action of the spring 43 mounted on the cam support plate 39. When the contact portion 35 abuts against the flat surface of the cam plate 42, the cam plate rotates rearward against the action of the spring 43.

Rotation of the cam plate 42 in the front-rear direction causes the action portion 44 of the action lever 45 fixed to the cam support plate 39.
And the action section is rotated by the second thread tension device 46.
The thread tension plate 49 of the contact portion 3 becomes or does not work, and the contact portion 3
When 5 comes into contact with the recessed portion 56 of the cam plate 42, the action portion 44 rotates forward to act on the thread tension disc 49, and thus the thread release state. The tension with respect to the second thread tension device is zero.

In FIG. 7, the position of the action portion 44 shown by the solid line shows the non-action state with respect to the thread tension disc 46, and the position of the action portion 44 shown by the dotted line shows the action state with respect to the thread tension disc.

Next, when performing winding sewing with three threads,
When the selection operation section 65 is operated, the second drive section 60 holds the lower looper thread hooking section 66 at the upper dotted line position shown in FIG. 11, and the first drive section 59 causes the swing lever 34 to move. By moving the contact portion 35 supported on the end portion to the right in the X direction in FIG. 11, the contact portion is brought into contact with the flat portion of the cam plate 42.

When the contact portion 35 comes into contact with the flat portion of the cam plate 42, the cam plate 42 moves rearward with the lower support shaft 38 as a fulcrum against the action of the spring 43 mounted on the cam support plate 39. Since it is rotated, the action portion 44 of the action lever 45 fixed to the cam support plate 39 is rotated to the position indicated by the solid line in FIG. 7, and the thread tension disc 49 of the second thread tension device 46 is inactive. Then the thread is clamped. In the second thread tension device, tension is applied to the thread.

Next, in the case of performing overedge sewing with two threads, when the selection operation section 62 is operated, the second drive section 6 is operated.
0, the lower looper thread hooking portion 66 is moved to the position of the lower solid line shown in FIG. 11 to correspond to the two-thread sewing, and the contact portion 35 is also moved downward, while the first
The contact portion 35 is moved to the left in the X direction in FIG. 11 by the drive portion 59 so that the contact portion is brought into contact with the flat portion of the cam plate 42.

When the contact portion 35 contacts the flat portion, the cam plate 42 is rotated backward against the action of the spring 43, so that the action portion 44 is rotated to the position shown by the solid line in FIG. The second tensioner device 46 moves and has no effect on the tensioner tray 49 of the second tensioner device 46, and the thread is clamped.

Next, when performing winding sewing with two threads,
When the selection operation section 63 is operated, the second drive section 60 keeps the lower looper thread hooking section 66 at the lower solid line position shown in FIG. 11 and also the contact section 35 at the lower position. By moving the contact portion 35 to the right in the X direction of FIG. 11 by the first driving portion 59, the contact portion is brought into contact with the first recessed portion 41 of the cam plate 42.

When the contact portion 35 comes into contact with the depressed portion of the cam plate 42, the cam plate 42 is rotated forward by the action of the spring 43, so that the action portion 44 is moved to the position shown by the dotted line in FIG. To the thread tension disc 49 of the second thread tension device 46 so that the thread is released.

The structure and operation of one embodiment of the present invention are as described above, and the sewing method command selected and operated by the sewing method selecting means 61 is obtained by advancing according to the sewing control routine shown in FIG. It is a thing.

[0030]

[Effect] Since the present invention has the above-mentioned structure and functions, the selection of the normal sewing or the winding sewing of the overedging and the selection of the two threads, the three threads or the four threads are combined. The operation of the thread tensioning device and the movement of the thread hooking section can be performed by the drive section, and the operation is extremely easy and the result is quick. Therefore, it is expected that the efficiency of the overedging work can be improved, and the practical and industrial effect will be remarkably large.

[Brief description of the drawings]

FIG. 1 shows an embodiment of the present invention. FIG. 1 is a perspective view of a conventional overedged sewing machine, FIG. 2 is a configuration diagram of a thread for normal overedging with three threads, and FIG. Fig. 4 is a configuration diagram of a thread for normal stitching of overedging with this thread, Fig. 4 is a configuration diagram of thread for winding stitch of overedging with 3 threads, and Fig. 5 is 2
Fig. 6 is a configuration diagram of the thread of the winding stitch of the overedging stitch using the main thread.
FIG. 7 is an external perspective view of a sewing machine showing an embodiment of the present invention, FIG. 7 is a sectional view of a second thread tension device showing an essential part of the embodiment of the present invention, and FIG. 8 shows an embodiment of the present invention. 9 is a side view of the thread tension switching mechanism shown in FIG. 8, FIG. 9 is an enlarged view of the thread tension switching mechanism shown in FIG. 9, and FIG. FIG. 12 is a front view of a thread tension switching mechanism showing an embodiment, FIG. 12 is an exploded perspective view of an essential part of the thread tension switching mechanism shown in FIG. 11, FIG. 13 is a control block diagram showing an embodiment of the present invention, and FIG. 14 is a book. It is a control flowchart which shows one Example of invention. 1st, 2nd, 3rd, 4th ... 1st thread tension device 12 ... Needle bar 13 ... Needle 14 ... Lower looper 15 ... Upper looper 46 ... Second thread tension device 59, 60 ... Driving part 61 ... Sewing method selecting means 69 ... Thread hook

Claims (1)

[Claims] 1. A needle bar, which is movably supported in a vertical direction on a sewing machine frame and has a sewing needle attached to a lower end thereof, a lower looper which oscillates in synchronization with a vertical movement of the needle bar, and a vertical movement of the needle bar. In an overlock stitch sewing machine including an upper looper that swings in synchronization with swinging of the lower looper, a plurality of threads that apply tension to a plurality of threads guided to each of the needle, the lower looper, and the upper looper. The first thread tension device of
A second thread tension device that can apply more tension to the thread introduced into the lower looper is provided, and the position can be changed in the thread introduction path between the second thread tension device and the lower looper. Of the sewing machine, wherein a thread hooking portion is provided, and the thread hooking portion is driven by the operation of the sewing method selecting means to switch the second thread tension device between working and non-working. Thread tension quick switching device.