JPH0815514B2 - Method and apparatus for adjusting lower thread tension of looper for lower thread - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for sequentially feeding a lower thread used for sewing a sewing machine to a lower thread looper with an appropriate tension. The tension at the time of bobbin thread feeding to the looper can be adjusted in stages to prevent slackening and loosening of the material to be sewn and bobbin thread breakage due to unstable tension, so that good sewing can be performed. The present invention relates to a lower thread tension adjusting method for a lower thread looper.

[0002]

2. Description of the Related Art In general, a sewing machine is capable of sewing various patterns by changing the number of needles and the ratio of the lower thread looper to the lower thread looper. Is a 1: 1 double chainstitch sewing machine, a flat twin sewing machine with a needle to bobbin looper ratio of 2: 1, a flat three sewing machine with a needle to bobbin looper ratio of 3: 1, needle to lower Ratio of looper for thread is 4
There are various types such as a pair of seamer sewing machines, and any one is used depending on the material to be sewn and the purpose of sewing. For example, when performing double thread double chain stitch when the sewing machine has one needle, after the needle penetrates the material to be sewn and is located at the lowest point, the needle loops the needle thread. While making, it moves up and the looper for bobbin thread enters and engages in the loop of the needle thread. Next, after the material is fed to the next stitch by the feeding mechanism, the lower thread looper performs a retracting operation for the needle, and at the same time, the needle enters the loop of engagement between the lower thread and the needle thread of the looper, When the lower thread looper is completely retracted from the needle, the needle reaches the lowest point again. By repeating the above-mentioned operations, the double chain stitch for the material to be sewn is completed.
Also, in the case of four-thread double chain stitch when there are three needles, three needles pass through the material to be sewn and are positioned at the lowest point, and then each needle loops into each needle thread. While making up, the lower thread looper enters into and engages with all loops of each needle thread. Next, after the material is fed to the next stitch by the feeding mechanism, the lower thread looper performs a retracting operation for each needle, and at the same time, each needle is formed between the lower thread and each needle thread of the looper. When the lower thread looper is completely retracted from each needle, each needle reaches the lowest point again. By repeating the above-mentioned operations, the double chain stitch for the material to be sewn is completed. Therefore, in order to neatly perform sewing with respect to the material to be sewn as described above without causing twitching or slack, loop formation by the inter-thread between the needle and the bobbin looper when the looper for bobbin thread always operates in association with each other. It is necessary to adjust the predetermined tension in a continuous and smooth manner. Especially, the lower thread tension adjustment of the lower thread looper is performed by adjusting the thread tension, thread slack, and thread return according to each needle operation. Since it is necessary to repeatedly perform the operation and the thread pulling operation, this is an important problem that is closely related to the quality of sewing. Conventionally, in this type of sewing machine, as a method for continuously adjusting the lower thread tension of the lower thread looper for the needle in accordance with the step of retracting the needle, a spider-shaped rotary cam as shown in FIG. 1 is used. There was no other way than to. That is, in the method of adjusting the lower thread tension of the lower thread looper using the claw-shaped rotary cam shown in FIG. 1, the rotary cam installation groove 4 is provided in the sewing machine arm 1 below or inside the sewing machine arm 2, or in the sewing machine bed 3. A method in which a claw-shaped rotating cam 5 is internally provided in the groove 4 and the hooking and releasing of the lower surface of the rotating cam 5 by the end 7 of the flat surface 6 is used to pull the lower thread, pull the thread, loosen the thread, and the like. This is a method in which the rotary cam 5 is adapted to continuously move up and down the needle 8 to continuously adjust the tension of the lower thread, and it is well known that almost all sewing machines adopt this method.

[0003]

However, in the conventional method of adjusting the lower thread tension of the lower thread looper described above, the claw-shaped rotary cam 5 is used.
Is configured so that it can rotate in a direction orthogonal to the installation direction of the sewing machine arm 2, and the lower thread must be arranged so as to engage in a direction orthogonal to the rotational direction of the rotary cam 5, so that the lower thread is pulled up by hand. That is, during the thread tensioning operation after the thread slackening operation, the thread winding phenomenon or the thread drawing phenomenon into the rotary cam installation groove 4 of the sewing machine bed 3 is caused, and the thread breakage is often caused. . Further, in connection with the thread breakage problem, the lower thread is inserted into the lower thread guide holes 51, 51 arranged on both sides of the rotary cam 5 in order to dispose the lower thread at the engagement position of the rotary cam 5 again. In this case, the rotary cam 5 is installed at the end as much as possible, and the lower thread is the cam 5
Since it has to be inserted in both lateral directions orthogonal to the above, there is a drawback that the insertion work is difficult and wasteful time and labor are required. Therefore, especially in recent years, there has been a strong and strong demand for the development of a bobbin thread tension adjusting method for a sewing machine, which does not cause a thread breakage phenomenon, facilitates thread insertion work, and can be carried out at low cost. The current situation is that the development of means that can do this has not been done yet.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and eliminates the fixed concept of the bobbin thread tension adjusting method for the bobbin thread looper, and provides a technical idea based on a novel idea. It is possible to adjust the tension of the lower thread looper for feeding the lower thread by a stepwise adjustment so that the tension is always in a good state. It is possible to prevent phenomena such as bobbin thread breakage and bobbin thread drawing due to cam rotation.
The purpose of the present invention is to provide a method for adjusting the lower thread tension of a lower thread looper that facilitates re-insertion work when the lower thread breaks and enables as good sewing as possible.

[0005]

The method for adjusting the lower thread tension of the lower thread looper of the present invention is a sewing machine having at least one or more needles, and when the lower thread is fed to the lower thread looper. A bobbin thread tension adjusting method in which a tensioning operation, a thread slacking operation, a thread returning operation, and a thread pulling operation are sequentially and repeatedly performed, and the method is provided at an arbitrary position for engaging with a bobbin thread of a sewing machine arm or a sewing machine bed. The tension adjusting lever is configured to reciprocate forward / backward, reciprocate up / down, reciprocate laterally or reciprocally swing in conjunction with the raising / lowering movement of the needle, and to loosen and tension the lower thread of the lower thread looper corresponding to the needle. The feature is that it can be adjusted appropriately.

[0006]

Therefore, the bobbin thread tension adjusting method of the bobbin thread looper according to the present invention has the following effects by being configured as described above. That is, the lower thread tension adjusting method for the lower thread looper of the present invention is configured such that a tension adjusting lever provided at an arbitrary position for engaging the lower thread is repeatedly advanced and retracted or repeatedly moved up and down in association with the vertical movement of the needle. Alternatively, since it is a method of adjusting the bobbin thread tension to the bobbin looper by repetitive lateral movement or repetitive oscillation, phenomena such as bobbin thread breakage due to unstable tension and bobbin thread pull-in due to cam rotation may occur. Therefore, the looseness and tension of the lower thread of the lower thread looper, which is interlocked with the needle, can be adjusted appropriately at all times to perform good sewing.

[0007]

FIG. 2 shows an embodiment showing a tension adjusting lever 15 according to the lower thread tension adjusting method of the lower thread looper of the present invention, and FIG. 3 adopts the tension adjusting lever 15. 1 shows an embodiment of a four-thread double chainstitch sewing machine 11. The four-thread double chainstitch sewing machine 11 is a sewing machine bed 1
2, a sewing machine arm 13 is provided on the upper part of the sewing machine 2, three needles 14 are attached to a lower end of the tip of the sewing machine arm 13 and repeatedly move up and down by hand, and the sewing machine bed 12 is provided with the respective needles 14. 14 is interlocked with the lower thread looper 16 that feeds the lower thread through the tension adjusting lever 15 so that the material to be sewn is subjected to double chain stitching.

When the lower thread is fed to the lower thread looper 16, the tension adjusting lever 15 corresponds to the needle 14 to sequentially perform a thread tensioning operation, a thread slackening operation, a thread returning operation, and a thread pulling operation. The tension adjusting lever 15 is repeatedly performed so that the slack and tension of the lower thread can be adjusted appropriately. The tension adjusting lever 15 is, for example, as shown in FIGS. A drive mechanism formed in an L-shape having a first hooking portion 151 for thread hooking and a second hooking portion 152 for bobbin thread hooking formed in a recess near the tip end portion and arranged inside the sewing machine bed 12 ( (Not shown), the needle 14 is repeatedly rocked in conjunction with the vertical movement of the needle 14. 1
Reference numeral 53 is a lower thread guide hole provided at a position orthogonal to the swinging direction on both sides of the tension adjusting lever 15, and the tension is adjusted by inserting the lower thread into the pair of lower thread guide holes 153 and 153. When the lever 15 swings, the lower thread hooking first engaging portion 151
The lower thread is appropriately engaged with the lower thread hooking second engaging portion 152 so that the lower thread tension can be fed while adjusting the lower thread tension with respect to the lower thread looper. Further, in the present embodiment, the tension adjusting lever 15 adopting the lower thread tension adjusting method of the lower thread looper of the present invention is used as the lower thread hooking first engaging portion 151.
Although the tension adjusting lever 15 including the lower thread hooking second engaging portion 152 is illustrated, the shape thereof is not particularly limited as long as the method is used. Further, in the present embodiment, the tension adjusting lever 15 is exemplified to be repeatedly oscillated in conjunction with the raising / lowering movement of the needle 14, but in this case as well, the repetitive movement is made to interlock with the raising / lowering movement of the needle 14. If it does, the repeating direction is arbitrary, and it may be repeated forward / backward movement, repeated vertical movement, or repeated lateral movement.

[0009]

Concrete action of the embodiment The tension adjusting lever 15 according to the method of adjusting the lower thread tension of the lower thread looper of the present invention configured as described above continuously and sequentially repeats each operation from FIG. 6 to FIG. The tension adjusting lever 15 and each needle 14
The relationship and operation with the above will be sequentially described. First of all, when the three needles 14 are retracted from the material to be sewn to the uppermost point as shown in FIG.
4, the tension adjusting lever 15 in this case is also the closest to the lower thread looper 16 as shown in FIG.
In preparation for the next operation, a thread tensioning operation is performed in which the lower thread is released from the second thread hooking portion for hooking the thread, while approaching in synchronization with. Secondly, when each of the three needles 14 is slightly lowered and positioned in the state shown in FIGS. 5 and 11 with respect to the material to be sewn, the lower thread looper 16 is retracted from the needle 14 in a slightly retracted state. In this case, the tension adjusting lever 15 is also retracted in synchronization with the lower thread looper 16 as shown in FIGS. 5 and 7, and the lower thread is engaged with the lower thread hooking first engaging member of the tension adjusting lever 15. Pull part 151
The yarn is slackened by and becomes a state in which it is engaged. Thirdly, when the three needles 14 start penetrating the material to be sewn and are positioned in the state shown in FIG. 12, the lower thread looper 16 moves the needle 14
8 and the tension adjusting lever 15 in this case is further retracted in synchronization with the lower thread looper 16 as shown in FIG. 8 and the lower thread is used for hooking the lower thread of the tension adjusting lever 15. The bobbin thread is separated from the first pulling portion 151, and the bobbin thread is returned to the next step. Fourth, when the three needles 14 respectively penetrate the material to be sewn and are located at the lowest points as shown in FIGS. 4 and 13, the lower thread looper 16 is shown in FIG. As shown in FIGS. 4 and 9, the tension adjusting lever 15 in this case is retracted farthest from the needle 14, and the tension adjusting lever 15 is retracted to the lower thread looper 16 in synchronization with the lower thread for hooking the lower thread. The threading operation is performed by the second hooking section 152, and the most hooked state is obtained. Furthermore, after completing the above-mentioned first to fourth operations, the engagement with the lower thread is released through the third operation to return to the original position. Then, the above-mentioned operations are continuously and sequentially repeated to appropriately adjust the looseness and tension of the lower thread of the lower thread looper 16 corresponding to the needle 14.

Next, a description will be given of the case where the sewing is performed using the four-thread double chainstitch sewing machine 11 employing the tension adjusting lever 15 according to the lower thread tension adjusting method of the lower thread looper of the present invention. After each of the three needles 14 with respect to the cloth is positioned at the lowest point by performing the above-mentioned first to fourth operations, each needle 14
When the needle thread rises while forming a loop on each needle thread and shifts to the first state through the third operation, the lower thread looper 16 has the length most retracted by the lower thread hooking second engaging portion 152. When the lower thread is released, it enters into the entire loop of each needle thread, and the engagement between the needle thread and the lower thread is completed. Then, after the material is fed to the next stitch by the feeding mechanism, the bobbin thread looper 16 performs a retracting operation for each needle 14, and at the same time, the tension adjusting lever 15 sequentially performs the first operation to the fourth operation. The needles 14 are continuously moved into the engagement loops formed between the lower thread of the lower thread looper 16 and the respective needle threads of the respective needles 14, and the lower thread looper 16 is moved from the respective needles 14 to each other. When completely retracted, each needle 14 reaches the lowest point again. Then, the above operation is continuously repeated to complete the double chain stitch for the material to be sewn.

[0012]

According to the bobbin thread tension adjusting method of the bobbin thread looper of the present invention, the tension adjusting lever provided at an arbitrary position for engaging the bobbin thread is repeatedly moved forward or backward in conjunction with the vertical movement of the needle. This is a method for constantly adjusting the bobbin thread tension to the looper for bobbin thread by repeatedly operating the tension adjusting lever so that the bobbin thread looper is configured to be repeatedly moved up and down, repeatedly moved sideways, or repeatedly rocked. Unlike the conventional bobbin thread looper tension adjusting method for bobbin thread that engages the bobbin thread by rotating the claw-shaped rotating cam in the orthogonal direction, bobbin thread breakage due to unstable tension, It is possible to prevent the bobbin thread drawing phenomenon into the rotary cam installation groove when the cam is rotating,
You can always perform stable sewing. Further, when the present invention is adopted, the lower thread guide hole is provided on both sides of the tension adjusting lever, but the conventional rotary cam which is always located at a height higher than the installation height of the lower thread guide hole is used. Unlike the above case, the lower thread hooking engagement portion of the tension adjusting lever, which is always located at a height higher than the installation height of the lower thread guide hole, is moved by advancing / retracting, raising / lowering, moving sideways, or swinging. There is an advantage that the insertion work into the lower thread guide hole at a position other than the engaging portion is easy, and the insertion work can be shortened. Therefore, the bobbin thread tension adjusting method of the bobbin thread looper of the present invention completely changes the basic concept to solve the conventional drawbacks and problems, and also satisfies various needs, and enables a sewing machine using a plurality of needles to be used. This is useful because it can be applied to all sewing machines using a rotating cam.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an embodiment when a conventional method is used.

FIG. 2 is an explanatory view showing an embodiment when the present invention is used.

FIG. 3 is an explanatory view showing a four-thread double chainstitch sewing machine using the present invention.

FIG. 4 is an explanatory view showing a lower thread engagement state of a tension adjusting lever using the present invention.

FIG. 5 is an explanatory diagram showing a lower thread engagement state of a tension adjusting lever using the present invention.

FIG. 6 is an explanatory view showing a lower thread engagement state of a tension adjusting lever using the present invention.

FIG. 7 is an explanatory view showing a lower thread engagement state of a tension adjusting lever using the present invention.

FIG. 8 is an explanatory view showing a lower thread engagement state of a tension adjusting lever using the present invention.

FIG. 9 is an explanatory view showing a lower thread engagement state of a tension adjusting lever using the present invention.

10 is an explanatory diagram showing a state of the needle corresponding to FIG.

11 is an explanatory diagram showing a state of the needle corresponding to FIG. 7. FIG.

12 is an explanatory diagram showing a state of the needle corresponding to FIG. 8. FIG.

13 is an explanatory diagram showing a state of the needle corresponding to FIG. 9. FIG.

[Description of sign]

 11 4-thread double chain stitch sewing machine 14 Needle 15 Tension adjusting lever 151 Lower thread hooking first hooking section 152 Lower thread hooking second hooking section 153 Lower thread guide hole 16 Lower thread looper

Claims (2)

[Claims] 1. In a sewing machine having at least one or more needles, when the lower thread is fed to a lower thread looper,
A bobbin thread tension adjusting method in which a thread tensioning operation, a thread slackening operation, a thread returning operation, and a thread pulling operation are sequentially repeated, and the method is provided at an arbitrary position for engaging a bobbin thread of a sewing machine arm or a sewing machine bed. The tension adjusting lever repeatedly swings while interlocking with the raising and lowering of the needle, and the tension adjusting lever moves the needle up and down.
Thread tension operation and thread slack movement of the lower thread of the lower thread looper corresponding to
Work, thread return operation, and thread pulling operation should be repeated in sequence.
A method for adjusting the lower thread tension of the lower thread looper, which is characterized in that 2. A device having at least one needle
In the thin, when sending the lower thread to the lower thread looper,
Thread tension operation, thread slack operation, thread return operation, thread pull operation
A bobbin thread tension adjusting device which is repeatedly performed, said device
Engages with the lower thread of the sewing machine arm or sewing machine bed
The first hooking portion for hooking the lower thread, which is slightly curved at any position
And a second hooking portion for hooking the lower thread, which is formed in a recess near the tip.
Deploying an L-shaped tension adjusting lever having
Then, the tension adjusting lever is arranged inside the sewing machine bed.
The drive mechanism repeatedly swings while interlocking with the raising and lowering of the needle.
A looper for bobbin thread that can be moved up and down by the tension adjusting lever.
Bobbin thread tensioning operation, thread slackening operation, thread returning operation, thread pulling operation
Bobbin thread characterized in that it is constructed so that the work is sequentially repeated
Looper tension adjusting device for looper .