JP2000308783A - Thread cutter of sewing machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten the remaining thread at the back of a workpiece after its thread has been cut by providing a notch along the thread guiding track by a capture member at a needle hole guiding boss capable of supporting a needle. SOLUTION: When the thread cutting drive mechanism at a sewing machine side is driven by a thread cutting signal during sewing, a capture member 7 rotates in the counterclockwise direction R1, which causes a thread handling part 7a of the capture member 7 to select threads not to be cut and a capturing part 7b to capture the remaining needle thread and bobbing thread T to be cut. When the capture member 7 rotates in the clockwise direction, the remaining needle thread and bobbing thread T to be cut is guided to a notch 12b of a needle hole guide 12, and then guided to an insulated notch 5a with contacted with the tip 4a of a heating element. The capture member 7 reaches the rotational end position in the clockwise direction, electrical current applied heats the tip 4a of the heating element, and after a specified time is elapsed, the needle thread and bobbing thread T contacted with the tip 4a are cut at a specified point.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thread cutting device for a sewing machine, which fuses a heating element, which has been heated by applying an electric current, with a sewing thread.

[0002]

2. Description of the Related Art Conventionally, in the case of cutting a twisted yarn composed of a plurality of single yarns in an industrial sewing machine, after the cutting, each single yarn is broken from a cut portion, and the cut portion has a poor appearance. there were. In addition, when the specially coated yarn is cut, there is a problem that the cutting condition of the knife is dulled to cause a poor thread cutting. In order to solve such a problem, there has been provided a thermal thread trimmer that fuses a heating element that is heated by applying an electric current to a sewing thread.

[0003]

However, in the conventional thermal thread cutting device, the thread cutting path becomes longer due to the needle hole guide boss, and the thread remaining on the back side of the sewing product after the thread cutting becomes longer. There was a problem that it would. Then, since the removal of the needle hole guide boss portion prevents the formation of the needle thread loop, there is a problem that the quality of the sewn product is deteriorated.

Further, there is a problem that the upper thread and the lower thread, which are guided to the cut portion at the time of thread cutting, are twisted in the cutting path, and the appearance of the upper thread and the lower thread welded after cutting is spoiled. there were. Further, when the upper thread is wiped by the wiper after the thread is cut, there is a problem that resistance is generated in the upper thread and the thread is not wiped well. SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and in a thermal thread cutting device that melts a thread by heat, it is possible to shorten a thread remaining on the back side of a sewing product after the thread is cut. It is a first object of the present invention to provide a sewing machine thread trimming device. It is a second object of the present invention to provide a thread trimming device for a sewing machine in which an upper thread and a lower thread welded after cutting have a good appearance and sewing quality can be improved.

Another object of the present invention is to provide a sewing machine thread trimmer in which when the upper thread is wiped off with a wiper after the thread is cut, an unnecessary resistance is not generated in the upper thread and the thread removing operation is reliably performed. This is the purpose of 3.

[0006]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a first aspect of the present invention is to provide a sewing needle which moves up and down in conjunction with a main shaft of a sewing machine, a needle plate for supporting an object to be sewn, and this needle plate. , Which has a boss portion facing downward and has a needle hole guide capable of supporting the sewing needle, and reciprocates in one direction to capture the upper thread and the lower thread on the side of the sewing material to be cut. A sewing machine fixed to the lower surface of the needle plate via an insulating plate, and a heating element that generates heat by passing an electric current; The boss portion of the needle hole guide is provided with a notch along a yarn guide trajectory by the catching means.

According to the first aspect of the present invention, the boss portion of the needle hole guide is provided with the notch along the yarn guide trajectory by the catching means. Since the upper and lower yarns captured by the capturing means are guided by the cutouts, they are guided to the heating element by the shortest path without being bent by the boss of the needle hole guide. For this reason, the thread remaining on the back side of the sewing product after the thread cutting can be shortened.

According to a second aspect of the present invention, in the sewing machine thread trimming device of the first aspect, the heating element is provided near a needle hole guide. According to the second aspect of the present invention, the thread remaining on the back side of the sewn product after thread cutting can be further shortened. The invention described in claim 3 is the invention according to claim 1.
In the above described thread cutting device for a sewing machine, the cutout end face of the boss portion of the needle hole guide and the insulating plate end face are configured to substantially coincide with each other in the vertical direction.

According to the third aspect of the present invention, the upper and lower yarns captured by the capturing means are guided to the heating element via the shortest path without being bent by the boss of the needle hole guide. For this reason, the thread remaining on the back side of the sewing product after thread cutting can be further shortened. According to a fourth aspect of the present invention, in the sewing machine of the first aspect, the width of the cutout portion of the boss portion of the needle hole guide supports the upper thread and the lower thread in a sewing portion side to be cut in parallel. Configured as possible.

According to the fourth aspect of the present invention, the upper and lower yarns caught by the catching means are guided in parallel with the notches. For this reason, since the upper and lower yarns welded after cutting are welded in a parallel state, the appearance is improved and the quality of the sewn product is improved. According to a fifth aspect of the present invention, in the sewing machine of the first aspect, the boss portion of the needle hole guide has a cutout within a predetermined angle range with respect to a loop forming direction.

According to the fifth aspect of the present invention, the notch of the needle hole guide boss is within a predetermined angle range with respect to the loop forming direction. For this reason, since the formation of the needle thread loop is not hindered, sewing failure such as skipping does not occur. According to a sixth aspect of the present invention, there is provided the sewing machine according to the first aspect, further comprising a wiper that wipes an upper thread of a sewing needle after cutting the thread,
The heating element is sandwiched between two insulating plates and fixed to the needle plate, and the lower insulating plate has a cutout along the movement path of the capturing unit.

According to the sixth aspect of the present invention, the upper and lower yarns captured by the capturing means are guided to the cutouts of the insulating plate. For this reason, when the upper thread is wiped with the wiper after the thread is cut, unnecessary resistance is not generated in the upper thread, and the thread removing operation is performed reliably.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to FIGS. FIG.
FIG. 2 is a bottom view of the thread cutting device 1 according to the first embodiment of the present invention as viewed from below the needle plate 10. FIG. 2 is an enlarged view of the vicinity of the needle hole guide of FIG. FIG. 3 is an explanatory view of the formation position of the notch of the needle hole guide. FIG. 4 shows ZZ of FIG.
It is a direction sectional view. FIG. 5 is an explanatory diagram showing a difference in the yarn path when the needle hole guide has no notch.

The thread cutting device 1 according to the first embodiment has a
This unit is configured by attaching the electric cords 2 and 2, the cord attachment 3, the heating element 4, the insulating plates 5 and 6, the capturing member 7, the capturing link 8, the capturing arm 9, and the like to the needle plate 10. The thread cutting device 1 is a unit including the needle plate 10 that can be attached to and detached from the sewing machine. When the thread cutting device 1 is not used, the connection rod 11 is detached from the capture arm 9 and the needle plate 10 together with the sewing machine, and another needle plate is attached to the sewing machine.

Reference numeral 13 in FIG. 4 denotes a sewing needle, which moves up and down in conjunction with a sewing machine spindle (not shown). A needle hole guide 12 having a boss portion facing downward is fixed to the needle plate 10 of FIG. The needle hole guide 12 regulates the vertical movement of the sewing needle 13 to guarantee a constant needle drop point, and guarantees the formation of a needle thread loop formed in the Y direction (loop forming direction) shown in FIG. Things.

As shown in FIG. 3, the boss portion 1 of the needle hole guide is provided.
A cutout 12b is formed in 2a in a predetermined direction.
It is preferable that this predetermined direction substantially coincides with the yarn guide trajectory (S direction in the drawing) by the capturing member (capturing means) 7. The notch 12b of the needle hole guide boss is located within a predetermined angle range with respect to the needle thread loop forming direction Y. The predetermined angle range W is preferably 120 degrees, more preferably 90 degrees, with respect to the axis X passing through the needle drop center point O and orthogonal to the loop forming direction, evenly distributed to the left and right. When the notch 12b is formed in the predetermined angle range W, the needle thread loop at the time of sewing is reliably formed. The width Q of the cutout of the needle hole guide boss is set to a size that can support the upper thread and the lower thread guided by the cutout in parallel. The width Q needs to be changed depending on the thickness of the upper and lower threads used. However, the thickness of the thread used is based on the thickness of the needle used. For this reason, it is necessary to change the needle hole guide in accordance with the change of the thickness of the needle to be used. At this time, the width Q of the cutout portion of the needle hole guide is also formed in advance to a size corresponding to the used thread. Have been.

The notch upper end surface 12c of the needle hole guide boss portion is arranged in the upper insulating plate 6 in the vertical direction shown in FIG.
Are located in the vertical range P on the end face of the. For this reason, the upper and lower threads T captured by the capturing member 7 are guided to the heating element via the shortest path without being bent by the boss portion 12a of the needle hole guide. Above the needle plate 10 is provided a wiper 14 for removing the upper thread U on the sewing needle side after thread cutting.

The catching member 7 shown in FIG. 1 is attached to the needle plate 10 so as to be rotatable by a pin 15. This capturing member 7
Is rotatable with respect to the needle plate 10 with a predetermined gap. The catching member 7 is provided with a catching portion 7b for catching the yarn to be cut in the forward direction in the clockwise direction in the figure, while a separating portion 7a for separating the yarn not to be cut is provided in the rearward direction. I have. The capturing link 8 and the capturing lever 9 constitute a link mechanism that transmits the movement of the connecting rod 11 to the capturing member 7.

The capture lever 9 is rotatably supported at the center about a connecting pin 9b, and is connected at one end to a connecting rod 11 so as to be rotatable about a rotating shaft 9a, and at the other end. It is connected to a capture link 8. The other end of the capturing link 8 is connected to the capturing member 7 in a rotatable state. The connecting rod 11 is connected to a thread cutting drive mechanism on the sewing machine that is driven at the time of thread cutting.

The heating element 4 is a plate-shaped member made of, for example, stainless steel or nichrome, and has both terminals 4b, 4c at the rear end.
To the electric cords 2, 2 and one terminal 4b
Is formed in such a shape that a current flows from the terminal 4a to the other terminal 4c via the tip 4a. And its tip 4
a, by reducing the width, the cross-sectional area is reduced,
The amount of heat generated at the distal end portion 4a is increased. For this reason, the amount of heat required for thread cutting can be obtained with low power. The electric cords 2 and 2 are connected to a transformer (not shown).

As shown in FIG. 4, the heating element 4 is fixed to the needle plate with screws (not shown) sandwiched between the insulating plate 6 on the needle plate 10 side and the lower insulating plate 5. At this time, the distal end portion 4a of the heating element has an arc shape along the needle hole guide boss portion, and can be mounted close to the needle hole guide 12 fixed to the needle plate 10. Also, the tip 4a of the heating element
Can be provided close to the needle hole guide 12 even if it is linear.

The electric cords 2 and 2 are fixed to the needle plate 10 while being connected to the heating element 4 by the cord attachment 3. Although a current flows through the heating element 4, as described above, since it is sandwiched and fixed between the insulators 5 and 6, the safety is not impaired even if the heating element 4 is brought close to the vicinity of the needle hole. In addition, the lower insulator 5 has a cutout portion 5 a formed along the yarn guide trajectory S of the upper and lower yarns T captured and moved by the capture member 7. A gap is provided between the notch 5a of the insulator and the capturing member 7. This gap reduces the resistance of the yarn when the upper and lower yarns T to be cut by the capturing member 7 are brought closer to the heat generating plate 4. Further, when the upper thread is wiped with the wiper 14 after the thread is cut, no extra resistance is generated on the upper thread.

Next, the operation of this embodiment will be described. When a thread cutting signal based on the sewing pattern data is sent during sewing, the thread cutting drive mechanism on the sewing machine side is driven. By driving the thread cutting drive mechanism, the connecting rod 11 is pushed and moves upward in the figure, and the movement is transmitted via the capture lever 9 and the capture link 8, so that the capture member 7 is moved in the counterclockwise direction R1 in the figure. Rotate. By the rotation in the counterclockwise direction, the yarn which is not cut by the yarn separating portion 7a of the catching member 7 (the needle on the needle side of the upper yarn) is further divided, and the remaining upper and lower yarns T to be cut (the upper yarn The yarn on the cloth side of the yarn and the lower yarn) are captured.

Next, the connecting rod 11 is pulled and moves downward in the figure, and the capturing member 7 rotates clockwise R2. As shown in FIG. 4, the clockwise rotation of the capturing member 7 causes the upper and lower threads T to be cut to be guided by the notch portions 12b of the needle hole guides, and then to contact the distal end portion 5a of the heating element 5. Then, the upper and lower threads T are guided into the lower insulator notch 5a.

After the capturing member 7 is positioned at the clockwise rotation end as shown in FIG. 1, a heating signal is issued to the transformer, and a current flows through the heating element 4 via the electric cords 2 and 2, and the heating element The tip 4a is heated. Then, after a lapse of a predetermined time, the upper and lower threads T that have been in contact with the distal end portion 4a of the heating element are cut at predetermined cutting locations. Then, the upper thread on the sewing needle side after the thread cutting is threaded by the wiper 14.

In the present embodiment having the above-described configuration, the boss portion 12a of the needle hole guide 12 is provided with a notch portion 12b along the yarn guide path S by the catching member 7. Then, the upper and lower threads T captured by the capturing member 7 are
b, it is guided to the heating element 4 by the shortest path without being bent by the boss portion 12a of the needle hole guide. FIG.
As shown in FIG. 5, the thread path becomes V when the conventional needle hole boss 12a has no notch, but the thread path becomes T when the conventional needle hole boss 12a has the notch 12b. For this reason, the thread remaining on the back side of the sewing product after the thread cutting can be shortened.

Further, since the heating element 4 is provided in the vicinity of the needle hole guide 12, the thread remaining on the back side of the sewing product after the thread cutting can be made shorter. The notch end face 12c of the boss portion of the needle hole guide 12 and the upper insulating plate end face 6a
They are almost the same in the vertical direction. Therefore, the capturing member 7
The upper and lower threads T caught by the boss 1 of the needle hole guide
The thread that is guided to the heating element 4 via the shortest path without being bent to the side 2a and that remains on the back side of the sewn product after thread cutting can be further shortened. Notch 1 of the boss of the needle hole guide
The width Q of 2b can support the upper and lower threads T on the sewing portion side to be cut in parallel. For this reason, the upper and lower threads T captured by the capturing member 7 are guided in a state of being parallel to the cutouts 12b. For this reason, since the upper and lower threads T welded after cutting are welded in a parallel state, the appearance is improved and the quality of the sewn product is improved.

The boss 12a of the needle hole guide has a notch 12b within a predetermined angle range W with respect to the loop forming direction.
Is provided. For this reason, since it does not prevent the needle thread loop formation,
No sewing defects such as skipped stitches occur. The heating element 4 is 2
The lower insulating plate 5 is provided with a notch 5 a along the yarn guide path S by the catching member 7 while being fixed to the needle plate 10 by being sandwiched between the two insulating plates 5 and 6. The upper and lower threads T captured by the capturing member 7
a. For this reason, when the upper thread U on the sewing needle side is wiped by the wiper 14 after the thread is cut, unnecessary resistance is not generated in the upper thread, and the thread sweeping operation is reliably performed.

[0029]

According to the first aspect of the present invention, the boss of the needle hole guide is provided with the notch along the thread guide path by the catching means. Since the upper and lower yarns captured by the capturing means are guided by the cutouts, they are guided to the heating element by the shortest path without being bent by the boss of the needle hole guide. For this reason, the thread remaining on the back side of the sewing product after the thread cutting can be shortened.

According to the second aspect of the present invention, it is possible to further shorten the thread remaining on the back side of the sewn product after the thread is cut. According to the third aspect of the present invention, the upper and lower yarns captured by the capturing means are guided to the heating element via the shortest path without being bent by the boss of the needle hole guide. For this reason, the thread remaining on the back side of the sewing product after thread cutting can be further shortened.

According to the fourth aspect of the present invention, the upper and lower yarns captured by the capturing means are guided in a state of being parallel to the notches. For this reason, the upper and lower yarns welded after cutting are
Since it is welded in a parallel state, the appearance is good and the quality of the sewn product is improved. According to the fifth aspect of the present invention, the notch of the needle hole guide boss is within a predetermined angle range with respect to the loop forming direction. For this reason, since the formation of the needle thread loop is not hindered, sewing failure such as skipping does not occur.

According to the sixth aspect of the present invention, the upper and lower yarns captured by the capturing means are guided to the cutouts of the insulating plate. For this reason, when the upper thread is wiped with the wiper after the thread is cut, unnecessary resistance is not generated in the upper thread, and the thread removing operation is performed reliably.

[Brief description of the drawings]

FIG. 1 is a bottom view of a thread cutting device 1 of the present embodiment as viewed from below a needle plate 10;

FIG. 2 is an enlarged view of the vicinity of the needle hole guide of FIG. 1;

FIG. 3 is an explanatory diagram for explaining a formation position of a notch of a needle hole guide;

FIG. 4 is a plan view in the ZZ direction of FIG. 1;

FIG. 5 is an explanatory diagram showing a difference in a yarn path when a notch is not provided in a needle hole guide.

[Explanation of symbols]

 4 Heating element 5 Lower insulator 5a Insulator cutout 6 Upper insulator 7 Capture member (capture means) 10 Needle plate 12 Needle hole guide 12a Needle hole Guide notch 13, sewing needle 14, wiper S, thread guide trajectory

Claims (6)

[Claims] 1. A sewing needle which moves up and down in conjunction with a main shaft of a sewing machine, a needle plate for supporting an object to be sewn, a boss portion fixed to the needle plate, and having a boss downward, and capable of supporting the sewing needle. A needle hole guide; catching means for reciprocating in one direction to catch an upper thread and a lower thread on the side of a sewing product to be cut; fixed to the lower surface of the needle plate via an insulating plate; A threading device that cuts off the thread by bringing a sewing thread into contact with the heating element. A thread trimming device for a sewing machine, comprising a notch. 2. The thread trimming device for a sewing machine according to claim 1, wherein said heating element is provided near a needle hole guide. 3. The thread of the sewing machine according to claim 1, wherein the notch end face of the boss of the needle hole guide and the insulating plate end face substantially coincide with each other in the vertical direction. Cutting device. 4. The thread cutting device for a sewing machine according to claim 1, wherein the width of the cutout of the boss portion of the needle hole guide is such that the upper thread and the lower thread on the sewing portion side to be cut can be supported in parallel. A thread trimming device for a sewing machine. 5. The thread of the sewing machine according to claim 1, wherein the boss portion of the needle hole guide has a cutout within a predetermined angle range with respect to a loop forming direction. Cutting device. 6. The sewing machine according to claim 1, further comprising a wiper for removing an upper thread on a sewing needle after cutting the thread, wherein the heating element is sandwiched between two insulating plates and fixed to the needle plate. A lower part of the insulating plate is provided with a notch along a thread guide path by the catching means.