JP2536955Y2 - Moving knife for thread cutting device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention [Industrial Application Field] The present invention relates to a moving knife of a thread cutting device of a sewing machine.

[Related Art] Conventionally, a sewing machine provided with a thread cutting device including a moving knife and a fixed knife below a needle plate is well known. As the moving knife A of such a thread cutting device, FIG.
As shown in (C), the one provided with a groove D for catching the sewing end side Ca of the needle thread C descending in a loop form from the needle hole B of the needle plate, and a front edge E contacting the needle side Cb. Are known. This leading edge E
Has a shape that is inclined rearward to slide the needle side Cb of the needle thread C in the lateral direction. The needle thread C and the bobbin thread F hanging from the needle hole B are caught in the groove D by the rotation of the movable knife A, guided through the guide groove H, and guided toward the protruding hemisphere G for cutting. . At this time, the bobbin side of the bobbin thread F hangs down from the bottom of the groove D.
Through to the needle I. And this moving knife A
In cooperation with the fixed knife J, the needle thread C is cut together with the bobbin thread F at the protruding hemisphere G at the bottom of the groove D.

Here, the inclination angle of the leading edge E (the apex angle of the protruding end portion) is set to about 70 ° in the drawing, the vicinity K of the leading edge E is ground and the thin portion L is adjacent to the guide groove H. Is formed.

[Problem to be Solved by the Invention] The inclination angle of 70 ° of the leading edge E is set so that the needle thread C can slide smoothly backward, so there is usually no problem. However, depending on the type and thickness of the yarn, as shown in FIG. 2 (C), the yarn may stop halfway without slipping sufficiently backward. In such a case, the needle thread C
Is cut at the edge position Pb of the fixed knife J, and causes a so-called “break”. For this reason, the amount of the thread end from the needle J may be insufficient, and the needle thread C may come off from the needle J, or it may be necessary to pull out the thread end when starting the next sewing.

In order to solve this, the inventor has devised a configuration in which the inclination angle of the leading edge E is steep, but in that case, the needle thread C
However, it was found that the above problem could not be solved only by making the inclination angle steep, because the amount of the yarn at the tip of the protruding hemisphere G for cutting became too small to slide backward.

Therefore, an object of the present invention is to provide a moving knife of a thread cutting device that can obtain a sufficient amount of thread end of a needle thread on a needle side after cutting without being affected by conditions such as the type and thickness of the thread. The idea was completed.

Configuration of the Invention [Means for Solving the Problems] In the moving knife of the thread cutting device according to the present invention, which has been made to achieve the above object, the sewing end side of the needle thread that has been lowered in a loop from the needle hole of the needle plate. And a leading edge that abuts on the needle side, and adjusts the amount of backward bending and / or inclination of the leading edge so that the needle side of the needle thread slides obliquely backward and cooperates with the fixed knife. A moving knife of a thread cutting device that cuts the needle thread together with the bobbin thread at the bottom of the groove, in the middle of the front edge, in the transverse direction with respect to the blade width of the fixed knife, and A position that is obliquely forward with respect to the bottom is defined as a capture position of the needle thread, and a capture claw that captures the needle thread that moves obliquely backward along the front edge is formed, and the capture position and the bottom of the groove are formed. The space between them is a thin portion.

[Operation] In the moving knife of the thread cutting device of the present invention, the needle side of the needle thread slides obliquely backward along the front edge, but obliquely beyond the catching claw formed at a predetermined position in the middle of the front edge. It does not move backwards. Therefore, the leading edge can be greatly curved or formed at a steep angle without taking into account excessive movement of the needle thread.

[Embodiment] Next, an embodiment of the moving knife 1 of the thread trimmer that embodies the present invention will be described with reference to FIGS. 1A to 1C and while comparing with the above-described conventional example. Clarify the action and effect.

The moving knife 1 has a groove 7 for catching the sewing end edge 5a of the needle thread 5 which has been lowered in a loop from the needle hole 3 of the needle plate, a front edge 9 abutting on the needle side 5b, and a halfway of the front edge 9. And a catching claw 11 provided. In addition, similar to the moving knife A of the conventional example, a protruding hemisphere 13 for cutting and a guide groove 15 are provided, and a region from a portion adjacent to the guide groove 15 to a root of the catching claw 11 is a thin portion 17.

The leading edge 9 is about 50 ° in terms of the apex angle of the tip 9a, which is steeper than that of the conventional moving knife A. Further, the catching claw 11 is formed at a position displaced laterally with respect to the blade width of the fixed knife 20 and obliquely forward with respect to the bottom of the groove 7. It should be noted that the deviation from the lateral direction with respect to the blade width is an essential design condition. However, the diagonally forward position is determined by using the protruding hemisphere 13 as a starting point in consideration of the amount of curvature of the front edge 9. The length from the bottom to the needle 22 through the base of the catching claw 11 may be designed so as to satisfy a predetermined condition required as the thread end length of the needle thread 5 at the start of sewing.

The movable knife 1 catches the needle thread 5 and the bobbin thread 24 hanging down from the needle hole 3 immediately after the completion of the sewing in the groove 9 along with the rotation in the direction of the arrow in the drawing, and passes through the guide groove 15. It is captured while being guided toward the protruding hemisphere 13 for cutting. At this time, the bobbin side of the bobbin thread 24 hangs down from the bottom of the groove 9 as it is, but the needle thread 5 passes through the lower surface of the movable knife 1 to exit from the front edge 9 to the upper surface, passes through the needle hole 3 again, and passes through the needle hole 3. It becomes a loop that continues to 22. In this way, the moving knife 1 comprises the needle thread 5 and the bobbin thread.
24, and further moves toward the fixed knife 20 as it is, and performs cutting in cooperation with the fixed knife 20. Also,
During this movement, an unillustrated flip-up operation of the balance is performed, and the needle side of the needle thread 5 moves obliquely rearward along the front edge 9 and stops at the base of the catching claw 11.

Here, the leading edge 9 of the moving knife 1 of the embodiment has a more backward retreating method than the conventional moving knife A shown by a dotted line in FIG. It always moves to the base of the catching claw 11 without being affected by the type, thickness, etc. As a result, the needle thread 5 does not catch on the edge of the fixed knife 20 and is always cut at only one of the cutting positions P shown in the figure. Therefore, "break" does not occur, and the length of the thread end of the needle thread 5 remaining on the needle 22 is always sufficient as designed, and there is no fear of the thread coming off and the needle thread 5 may be removed before the next sewing. It is not necessary to do the work of drawing out.

Here, differences in the configuration, operation, and effect between the present embodiment and the conventional example will be compared.

First, the leading edge 9 of the moving knife 1 of the present embodiment is mainly
It has a structure, function, and effect that makes it easy to slide diagonally backward. Here, with this configuration alone, as pointed out as a problem, even if “bleeding” could be solved,
This does not solve the problem of "insufficient yarn". Further, at the time of cutting, a sufficient tension needs to be applied to the needle thread 5 in a portion from the protruding hemisphere 13 for cutting to the front edge 9 of the moving knife 1. In the case of the present embodiment, the needle thread 5 stops at the base of the catching claw 11, so that the tightening position is used as a tightening position, and sufficient tension is given by flipping up the balance after the stop. If the catch claw
Without 11, the needle thread would always slide backwards as the balance was flipped, and sufficient tension could not be obtained.

On the other hand, the conventional moving knife A utilizes the stop due to the frictional force with the leading edge E in order to obtain this sufficient tension. It could not be tilted.
In other words, in the conventional example, all the conditions are intended to be satisfied only by the angle of the leading edge E.

Here, there is a reason why there is no configuration that is curved as in the present embodiment. That is, in the case of bending, an effect of gradually making the vehicle slippery is exhibited, so that one of the objectives to be compatible (tightening by stopping) cannot be achieved. In this case, the amount of thread from the needle 22 may be insufficient.

As described above, the present embodiment employs a novel configuration that has not existed in the past, does not have the problem of "breaking" or "insufficient yarn amount", and can perform accurate cutting under a sufficient tension. It is.

Note that the present invention is not limited to the above-described embodiment, and various modes can be adopted without departing from the gist thereof.

For example, the front edge 9 may be formed in a straight line at a steep angle instead of a curved configuration. In addition, a combination of a curved line and a straight line may make it slippery. In short, the leading edge may be any one that aims to make it slippery by adjusting the amount of curvature, the amount of inclination, or an amount equivalent thereto. Also,
The specific angle of inclination of the front edge 9 and the formation position of the catching claw 11 are matters to be determined appropriately according to design conditions.

Effect of the Invention According to the present invention, a moving knife of a thread cutting device that can obtain a sufficient amount of thread end of the needle thread on the needle side after cutting without being affected by conditions such as the type and thickness of the thread. Can be provided. As a result, troubles at the time of thread trimming, such as thread breakage due to "breaks" or "insufficient thread amount", can be prevented, and preparation work for the next sewing can be reduced.

[Brief description of the drawings]

FIG. 1 (A) is a developed plan view of the moving knife according to the embodiment, FIG. 1 (B) is a sectional view taken along line XX, and FIG. 1 (C) is an embodiment in which the moving knife and the fixed knife cooperate with each other. 1 (D) is a side view thereof, FIG. 2 (A) is a plan development view of a movable knife of a comparative example, and FIG. 2 (B).
FIG. 2 (C) is a perspective view showing a state in which a movable knife and a fixed knife cut jointly in a comparative example. 1, A… moving knife, 3, B… needle hole in needle plate 5, C… needle thread, 7, D… groove 9, E… front edge, 11… catching claw 20, J… Fixed knife, 22, I ... Needle 24, F ... Bobbin thread

Claims (1)

(57) [Scope of request for utility model registration] 1. A groove for catching a sewing end side of a needle thread lowered from a needle hole of a needle plate in a loop shape, and a front edge contacting the needle side, wherein the front edge has a backward bending amount and / or. A moving knife of a thread cutting device for adjusting a tilt amount, sliding a needle side of a needle thread obliquely backward, and cutting a needle thread together with a bobbin thread at a bottom portion of a groove in cooperation with a fixed knife; In the middle of, moving to the position obliquely forward with respect to the blade width of the fixed knife and obliquely forward with respect to the bottom of the groove as the needle thread catching position, diagonally rearward along the front edge A moving knife for a thread cutting device, wherein a catching claw for catching a coming needle thread is formed, and a thin portion is provided between the catching position and the bottom of the groove.