CN1236034A - Thread cutter for sewing machine - Google Patents

Abstract

The utility model relates to a thread cutting device of a sewing machine. A thread stretcher and a thread cutter are centered on a horizontal axis and rotate in opposite directions respectively so as to cut the thread. In such a device there is provided an adjusting device which adjusts up and down the horizontal axis which is the center of rotation of the thread cutting device. to adjust the remaining thread length on the cloth after thread cutting.

Description

Thread cutting device for sewing machine

The present invention relates to a thread cutting device of a sewing machine, in particular to a cutting edge of a thread cutter and a thread stretcher, which are centered on a horizontal axis and rotate in opposite directions along the periphery of a needle cylinder to catch and cut off the thread. cutting device.

Such a conventional thread cutting device will be described with reference to FIGS. 6 and 7 .

1 is a central shaft, which is rotatably supported on a bearing 2 mounted on the sewing machine frame. 3 is a cutter holder, and the cylindrical base part 4 is rotatably supported by the shaft part 5 formed in the bearing 2. As shown in FIG. Further, on the outer periphery of the knife holder 3, a connecting portion 7 for supporting a connecting pin 6 protruding forward and a supporting portion 9 for fixing a thread cutter 8 forming a blade are provided.

10 is a gallows, and its cylindrical root 11 is rotatably loosely fitted on the outer periphery of the root 4 of the cutter frame 3 . Moreover, the outer circumference of the gallows 10 is provided with a connecting portion 12 and a supporting portion 14 for fixing a thread stretcher 13 forming a blade. A bifurcated hook 15 is formed on the thread stretcher 13 to arrange the thread to be cut and the thread not to be cut when the thread stretcher 13 rotates, and only catches the thread to be cut. On the base top surface of the hook 15, a convex portion 15a is formed.

16 is the drive shaft of the thread cutting device, on which the drive shaft 16 is provided with a drive arm 18 whose root is fixed on the drive shaft 16, the double fork 17 of the front end is connected with the connecting pin 6 of the cutter frame 3. Moreover, on the driving shaft 16, a stretching thread driving arm 19 whose root is fixed on the driving shaft 16 is provided. 20 is a connecting crescent plate, the upper end of which is rotatably connected to the connecting part 12 of the gallows 10, and the lower end is rotatably Connected to the front end of the thread driving arm 19.

21 is a needle jack plate, which is formed with pinholes 22 .

The conventional thread cutting device has the above structure, and its operation will be described below with reference to Fig. 7(a), Fig. 7(b) and Fig. 7(c).

Fig. 7(a) is the state of the thread cutting device before the thread cutting operation starts.

From this state, when the driving shaft 16 starts to rotate clockwise according to the thread cutting signal, first, the stretching thread driving arm 19 rotates the stretching gallows 10 clockwise by connecting the crescent plate 20 . Thread tensioner 13 also rotates thereupon, and its crotch 15 arranges the thread to be cut off and the thread not to be cut off, as shown in Figure 7 (b), only the thread to be cut off is caught in the crotch 15.

And when the drive shaft 16 starts to rotate clockwise, the drive arm 18 also rotates clockwise, and by its double fork 17 and connecting pin, the cutter frame 3 and the thread cutter 8 rotate counterclockwise.

When the thread tensioner 13 rotates clockwise, the thread cutter 8 rotates in the opposite direction to the above, and the two sides overlap as shown in Fig. line cut off.

When the thread was cut off, the drive shaft 16 began to rotate counterclockwise, the gallows 10 and the thread tensioner 13 rotated counterclockwise contrary to the above, the cutter frame 3 and the thread cutter 8 rotated clockwise, and returned to The initial position shown in Figure 7(a).

The thread is cut as described above. In the conventional thread cutting device shown in FIG. 6 and FIG.

However, in such a thread cutting device, it is sometimes required that the remaining thread length remaining on the cloth after the thread is cut through the sewing process be as short as possible.

In order to meet this requirement, the distance S between the bottom surface of the needle jack 21 and the cutting portion of the thread tensioner 13 and the thread cutter 8 should be made as close as possible.

In order to make this distance S close, in the conventional device, as a solution, the bottom surface of the needle lifter 21 is processed to make the needle lifter 21 thinner, so that the bottom surface of the needle lifter 21 and the stretched thread The method that the distance S between the cutter 13 and the cutting part of the thread cutter 8 is close.

However, in this method, since the thickness of the needle jack 21 is thinned, there is a problem that the needle jack 21 is damaged when the pressing force for pressing the cloth is increased when thick cloth is sewn.

In addition, the thickness of the needle jack 21 is set to a standard thickness in advance, and the surface of the needle jack 21 supporting the sewing machine bed is machined to be deep. Like this, when carrying out common remaining thread length sewing, add liner between the bottom surface of needle jack 21 and the needle jack supporting surface of sewing machine base plate, needle jack 21 is fixed on the sewing machine base plate and sews.

And when carrying out the sewing of the shorter remaining thread length, after removing the liner between the bottom surface of the needle jack 21 and the needle jack supporting surface of the sewing machine chassis, the needle jack 21 is fixed on the sewing machine chassis to shorten the length of the sewing machine. The distance S is used for sewing.

However, when sewing with a shorter remaining thread length, this method has the top surface of the needle jack plate 21 lower than the top surface of the sewing machine bottom plate, resulting in a height difference that hinders the feeding of the cloth, and the sewing operation cannot be performed smoothly. The problem.

In addition, as another method, it is conceivable to reduce the thickness of the needle jack 21 to be smaller than the thickness of the standard needle jack 21, so that the top surface of the needle jack and the top surface of the sewing machine bed are on the same plane.

When sewing in this state, the length of the remaining thread is shortened, but in this structure, in order to be applicable to the sewing of the lengthening of the remaining thread, the thin needle jack plate 21 will be replaced with a standard thick needle jack. Needle plate 21.

In this way, the standard thick needle jack plate 21 is higher than the top surface of the sewing machine bottom plate, resulting in a difference in height and hindering the feeding of the cloth. At the same time, it is difficult to arrange the cloth and the sewing operation cannot be carried out smoothly.

In order to solve the above problems, the structure of the present invention is: in the thread cutting device of the sewing machine, the thread stretcher and the thread cutter are centered on the horizontal axis, rotate in opposite directions around the needle cylinder, catch the suture and cut it , an adjustment device is provided to move the center of rotation of the thread stretcher and the thread cutter up and down.

According to the present invention, since the needle jack having a normal thickness is used, the sewing of the usual remaining thread length and the remaining thread length can be carried out under the condition that the top surface of the needle jack 21 and the top surface of the sewing machine bed are always kept at the same level. Shorter sewing, so has the following effect.

The needle jack plate will not be damaged as before, and at the same time, the top surface of the needle jack plate 21 and the top surface of the sewing machine bottom plate are always kept on the same plane, so that the feeding of the cloth is stable, and the efficiency of the sewing operation is improved.

Fig. 1 is a front view of a thread cutting device according to a first embodiment of the present invention.

Fig. 2 is an exploded perspective view of the thread cutting device according to the first embodiment of the present invention.

Fig. 3 is a cross-sectional view showing a state of vertical adjustment in the thread cutting device according to the first embodiment of the present invention.

Fig. 4 is an exploded perspective view of a thread cutting device according to a second embodiment of the present invention.

Fig. 5 is a cross-sectional view showing a state of vertical adjustment in the thread cutting device according to the first embodiment of the present invention.

Fig. 6 is an exploded perspective view of a conventional thread cutting device.

Fig. 7 is an explanatory view showing the operation of a conventional thread cutting device.

Embodiments of the present invention will be described below with reference to FIGS. 1 to 5 .

In addition, since the basic structure of the thread cutting device is the same as the conventional structure, these same structural parts are given the same reference numerals as in the prior art, and the description of these structures is omitted, and only the different structural parts will be described.

First, a first embodiment will be described with reference to FIGS. 1 to 3 .

23 is an eccentric shaft loosely fitted on the shaft portion 5 of the bearing 2 in a rotatable manner, and two grooves 24 are formed on the upper and lower end surfaces thereof.

The root portion 4 of the cutter holder 3 is loosely fitted on the outer periphery of the above-mentioned eccentric shaft 23 so as to be rotatable.

The gallows 10 is the same as the prior art, and is loosely fitted on the outer periphery of the root 4 of the cutter frame 3 in a rotatable manner.

25 is an adjustment plate, and two pins 26 that are respectively loosely fitted in the groove 24 of the eccentric shaft 23 are protrudingly supported on one side of the cutter frame 3. Like this, the adjustment plate 25 is fixed by two screws 27 as shown in Figure 3 On the end face of the shaft portion 5 of the bearing 2 .

An adjusting device is constituted by the above-mentioned eccentric shaft 23 and the adjusting plate 25 .

The first embodiment has the above-mentioned structure, and its operation will be described below.

Fig. 3 (a) is the state of carrying out the sewing of common excess thread length, as shown in Fig. 1, the distance from the bottom surface of the needle jack 21 to the part cut off by the thread tensioner 13 and the thread cutter 8 is S. In this state, as shown in FIG. 3( a), in a state where the center B of the eccentric shaft 23 is located below the center A of the central shaft 1, the adjustment plate 25 is fixed on the shaft portion 5 of the bearing 2 by screws 27. end face.

In the state of Fig. 1 and Fig. 3 (a), when the driving shaft 16 rotates clockwise according to the thread cutting signal, first, the stretching thread driving arm 19 makes the stretching gallows 10 move along the direction of the cutter frame 3 by connecting the crescent plate 20. The outer circumference of the root 4 turns clockwise. The thread stretcher 13 also rotates thereupon, and its crotch 15 arranges the thread to be cut and the thread not to be cut, and only the thread to be cut is caught in the crotch 15 .

And when the drive shaft 16 started to rotate clockwise, the drive arm 18 also rotated clockwise, and by its double fork 17 and connecting pin 6, the cutter frame 3 was connected to the thread cutter 8 on the periphery of the eccentric shaft 23. Turn together counterclockwise.

When the thread stretcher 13 rotates clockwise, the thread cutter 8 rotates counterclockwise, and both sides overlap as shown in Fig. 7(c), and the thread is cut off.

Afterwards, by the specified drive control signal, the drive shaft 16 starts to rotate in the counterclockwise direction, the gallows 10 and the thread tensioner 13 rotate in the counterclockwise direction opposite to the above, and the cutter frame 3 and the thread cutter 8 rotate in the clockwise direction , returning to the initial position shown in Figure 7(a).

Then, when performing short sewing with a short remaining thread length, perform the following adjustments.

From the state shown in FIG. 3( a), at first the two screws 27 are unscrewed, so that the adjustment plate 25 is in a free state relative to the shaft portion 5 of the bearing 2 . From this state, the adjustment plate 25 is rotated 180 degrees, because the two pins 26 supported on the adjustment plate 25 are respectively loosely fitted in the grooves 24 of the eccentric shaft 23, so the eccentric shaft 23 also rotates 180 degrees together with the adjustment plate 25 Spend.

As a result, the center B of the eccentric shaft 23 is also higher than the center A of the central shaft 1 as shown in FIG. 3( b ). On this position, screw 27 is tightened again, and adjusting plate 25 is fixed on the axle portion 5 of bearing 2.

Therefore, as shown in FIG. 3( b ), the distance from the bottom surface of the needle jack 21 to the portion cut by the thread tensioner 13 and the thread cutter 8 is a distance s shorter than the distance S described above.

As described above, when the distance from the bottom surface of the needle jack 21 to the portion cut by the thread tensioner 13 and the thread cutter 8 is shortened, the length of the thread remaining on the cloth after thread cutting is shortened.

Hereinafter, a second embodiment will be described with reference to FIG. 4 and FIG. 5 .

28 is a vertical groove formed on the above-mentioned bearing 2, and two upper and lower screw holes 29 are formed on its bottom. 30 is an adjustment body as an adjustment device, and is formed with a shaft that is loosely fitted in the root 4 of the cutter frame 3 31 and a protrusion 32 that is loosely fitted in the above-mentioned vertical groove 28 and protrudes in the vertical direction. Moreover, a longitudinal long hole 33 in which the central shaft 1 is loosely fitted is provided through the center of the adjusting body 30, and two longitudinal long holes 34 are provided through the upper and lower sides of the long hole 33. 35 is a screw. The long hole 34 is screwed into the screw hole 29 of the bearing 2 to fix the adjusting body 30 on the bearing 2 .

The second embodiment has the above structure, and its operation will be described below.

Fig. 5 (a) is the state of carrying out the sewing of the usual remaining thread length, as shown in Fig. 5 (a), the distance from the bottom surface of the needle jack 21 to the part cut by the thread tensioner 13 and the thread cutter 8 is S . In this state, as shown in FIG. 5(a), the center C of the shaft portion 31 of the adjustment body 30 is also located below the center A of the central shaft 1, and the convex portion 32 is fitted into the vertical groove 28 of the bearing 2. In the middle state, the adjustment body 30 is compressed and fixed on the bearing 2 by the screw 35 .

In this state, when the thread cutting device operates, the thread stretcher 13 and the thread cutter 8 rotate around the center C of the shaft portion 31 of the adjusting body 30 to cut the thread in the same manner as described above.

Then, in the second embodiment, when sewing with a short remaining thread length is performed, the following adjustments are performed.

From the state shown in Fig. 5(a), first, the two screws 35 are loosened. The fixing of the adjusting body 30 relative to the bearing 2 is thus released. From this state, the adjustment body 30 is pushed upwards. Therefore, the adjustment body 30 moves upwards along the vertical groove 28 only by the amount of the gap between the elongated hole 34 and the outer diameter of the screw 35. At this position, the screw 35 is screwed into the screw hole 29 to fix the adjustment body 30 on on bearing 2.

As a result, the center C of the shaft portion 31 of the adjustment body 30 is also higher than the center A of the central shaft 1 as shown in FIG. 5( b ), contrary to FIG. 5( a ).

Therefore, as shown in FIG. 5( b ), the distance from the bottom surface of the needle jack 21 to the portion cut by the thread tensioner 13 and the thread cutter 8 is a distance s shorter than the distance S shown in FIG. 5( a ).

As described above, as the distance from the bottom surface of the needle jack 21 to the portion cut by the thread tensioner 13 and the thread cutter 8 becomes shorter, the length of the thread remaining on the cloth after thread cutting becomes shorter.

As mentioned above, the present invention adopts the needle jack with normal thickness, and under the condition that the top surface of the needle jack 21 and the top surface of the sewing machine bottom are kept on the same level at all times, it is possible to carry out sewing with normal remaining thread length and sewing with remaining thread length. Sewing with a short thread length has the following effects.

The needle jack plate will not be damaged as before, and at the same time, the top surface of the needle jack plate 21 and the top surface of the sewing machine bottom plate are always kept on the same plane, so that the feeding of the cloth is stable, and the efficiency of the sewing operation is improved.

Moreover, since the adjustment operation can also be easily performed, it has good adjustment operability.

Claims (4)

1. the thread cutting device of a Sewing machines, stretch tight line device and tangential knife is the center with the horizontal axis, around the syringe that rotates, rotate in the opposite direction respectively, capture suture and with its cut-out, it is characterized in that: adjusting device is set, so that the above-mentioned center of rotation that stretches tight line device and tangential knife is moved up and down.

2. the thread cutting device of Sewing machines according to claim 1, it is characterized in that: in the above-mentioned adjusting device, the center of rotation of above-mentioned stretch tight line device and tangential knife can move up and down across above-mentioned horizontal axis.

3. the thread cutting device of Sewing machines according to claim 1 is characterized in that: above-mentioned adjusting device possesses the eccentric body that can rotate with respect to above-mentioned horizontal axis, and by rotating this eccentric body, above-mentioned center of rotation moves up and down.

4. the thread cutting device of Sewing machines according to claim 1, it is characterized in that: above-mentioned adjusting device and above-mentioned horizontal axis intersect, can be installed on the machine frame up or down.

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