JPH0238702Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a thread cutting device for a sewing machine that cuts captured sewing thread through cooperation between a movable blade and a fixed blade, and particularly relates to an improvement to ensure cutting of the sewing thread.

[Prior art] Conventionally, a movable blade in the form of a flat plate, which is capable of reciprocating motion below the throat plate so as to capture the sewing thread, and has a blade part formed on a part of the upper surface in the width direction, and a blade part along the width direction on the tip edge. In a thread cutting device having a fixed blade and a fixed blade having the blade portion facing each other above the movement path of the movable blade, both blade portions of the movable blade and the fixed blade engage to cut the thread between them.

[Problem to be solved] If the moving plane of the movable blade and the mounting plane of the fixed blade are not parallel, the engagement between the movable blade and the blade of the fixed blade will be inappropriate, and the thread will not be cut reliably. Ta. Usually, the pressure contact point of the fixed blade is pressed at a position corresponding to the engagement position between the blade part of the fixed blade and the blade part of the movable blade, in other words, a point on a line along the longitudinal direction of the fixed blade that passes through the engagement position. However, due to deformation of the machine frame to which the fixed blade or movable blade is attached, manufacturing errors, assembly errors, etc., this pressure contact point may be located in the width direction of the fixed blade relative to the above engagement position. This caused the thread to be misaligned, making it impossible to cut the thread reliably.
As a result, the worker has to use scissors to cut the threads connected to the cloth, which is a cumbersome task, which significantly reduces work efficiency, and the length of the sewing threads connected to the cloth is not constant, resulting in a decrease in the quality of the sewn product. This resulted in the following drawbacks.

This invention aims to eliminate the drawbacks of the above-mentioned conventional ones.

[Example] In FIGS. 1 and 2, 1 is a flat movable blade, which reciprocates on a horizontal plane below the throat plate in conjunction with the sewing machine main shaft or electromagnetic means (not shown).
A catching part (not shown) that is open at one side edge and can catch the sewing thread T during reciprocation, and a blade part 1a that is continuous with the catching part and projects upward are provided.

Reference numeral 2 designates a fixed blade that is formed by bending a flat plate vertically to form a Z-shape, and the lower flat part 2a has an arm part 2b projecting from the middle part to one side and a rear end edge lower than the center part in the width direction. The upper flat part 2d has a blade part 2e formed on its tip edge, and the support shaft 3 fixed to the machine frame is inserted into the hole 2f at the widthwise center of the lower flat part 2a. It fits loosely and is held immovably in the horizontal direction by a holding means (not shown) such as a protrusion provided on the machine frame, and the blade portion 2e is disposed facing above the movement path of the movable blade 1. The fixed blade 2 is supported against the machine frame only by the protrusion 2c, and the blade part 2e at the tip is tilted downward, and the fixed blade 2
is free to tilt in the width direction, so the tip is movable blade 1
They are in a parallel engaged state following the upper surface of the .

Reference numeral 4 denotes an L-shaped adjustment body, which is rotatably supported around a shaft 5 disposed on a line passing through the protrusion 2c and hole 2f of the lower surface 2a of the fixed blade 2, and has one free end attached to the arm 2b. A long hole 4a is formed at the tip of the hole facing along the
is formed, and is supported by the arm portion 2b through the adjusting screw 6 so as to engage the eccentric portion with the inner end surface of the elongated hole 4a.
A downwardly bulging pressing portion 4b is formed on the line at the other free end.

Reference numeral 7 denotes a leaf spring, which has a base end fixed to the machine frame, a tip end facing upwardly from the pressing portion 4b, and has an elastic force that presses the fixed blade 2 downward via the adjusting body 4. Therefore, the fixed blade 2, which is supported with respect to the machine frame only by the above-mentioned protrusion 2c, has its tip end blade 2e pressed against the upper surface of the movable blade 1 by the elastic force of the leaf spring 7.

This invention has the above-mentioned configuration, and the movable blade 1
reciprocates, and during the return movement, the catching section captures the sewing thread T and guides the thread T to the blade section 1a.
When the two blades are engaged, the sewing thread T is inserted into both blade parts 1a and 2.
Cut in cooperation with e.

As mentioned above, the fixed blade 2 is supported against the machine frame only by the protrusion 2c,
Since the blade portion 2e at the tip is tilted downward and freely tilted in the width direction, the tip edge follows the upper surface of the movable blade 1, so that it is always parallel to the upper surface and engagement is ensured. Further, the adjustment screw 6 is rotated to rotate the adjustment body 4 about the shaft 5, and the pressing portion 4b is moved to a position corresponding to the blade portion 1a of the movable blade 1. This means that the point of action of the elastic force of the leaf spring 7 is at the corresponding position above.
Therefore, the engagement of the blade portion 2e of the fixed blade 2 with the blade portion 1a of the movable blade 1 becomes strong.

In addition, in this embodiment, the adjusting body 4 is rotated to move the pressing part 4b in the width direction.
A pressing portion that bulges downward may be formed on the leaf spring 7 to move and lock the leaf spring in the width direction.
may be supported by the leaf spring 7.

[Effects] This invention consists of a flat movable blade that can reciprocate below the throat plate to capture the sewing thread, and has a blade part formed on a part of the upper surface in the width direction, and a blade part along the width direction that is attached to the tip edge. and a protrusion protruding downward from substantially the center in the width direction is formed on the rear edge, the blade part is freely inclined in the width direction around the protrusion, and the blade part faces the upper surface of the movable blade so as to be engageable with the upper surface of the movable blade. The arranged fixed blade, the pressing body that engages with the fixed blade at a position where it can be displaced in the width direction and presses the blade part of the fixed blade against the upper surface of the movable blade by elastic force, and the engagement position by the pressing body. By providing an adjusting means connected to the pressing body so as to be movable, the fixed blade is supported against the machine frame only by the protrusion, and the blade at the tip is tilted downward and in the width direction. Because it is free to tilt, the tip edge follows the top surface of the movable blade and is always parallel to the top surface, ensuring the engagement of both blades.Also, by rotating the adjusting body using the adjustment screw, the pressing part can be moved to the top of the movable blade. Since the engagement position between the blade part of the movable blade and the blade part of the fixed blade can match the position where the pressing force is applied, the engagement between the two blade parts can be strong. The effect of always ensuring thread trimming can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of the thread cutting device of this embodiment, and FIG. 2 is a plan view of the thread cutting device. In the figure, 1 is a movable blade, 2 is a fixed blade, 4b,
4 is a pressing body, and 4a and 6 are adjusting means.

Claims (1)

[Scope of Claim for Utility Model Registration] A movable blade 1 in the form of a flat plate that is movable reciprocally below the throat plate so as to capture the sewing thread and has a blade portion 1a formed on a part of the upper surface in the width direction, and a blade portion along the width direction. A protrusion 2e is formed on the leading edge, and a protrusion 2c protruding downward from approximately the center in the width direction is formed on the rear edge. fixed blades 2 disposed facing each other so as to be able to fit together, and pressing bodies 4b and 7 that engage with the fixed blades at positions that can be displaced in the width direction and press the blade portion of the fixed blades against the upper surface of the movable blades by elastic force. A thread cutting device for a sewing machine, comprising: adjusting means 4a, 6 connected to the pressing body so as to move the engagement position by the pressing body.