JP2762151B2 - Sewing machine thread cutting device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a thread cutting device for cutting a thread for sewing in a sewing machine.

[Conventional technology]

In this type of yarn cutting device, a pair of cutter elements provided below a needle plate are operated by a driving device to cut the yarn.

[Problems to be solved by the invention]

In this conventional thread cutting device, when a lump of thread is formed under the needle plate and bites into the cutter element at the time of the cutting operation, the cutter element cannot operate and the force applied from the driving device to the cutter element Is excessive, and there is a problem that the cutter element is damaged.

The present invention has been made to solve the above-mentioned problems (technical problems) of the prior art, and when a lump of thread is caught in a cutter element and cannot be operated, a drive device is used. An object of the present invention is to provide a thread cutting device for a sewing machine that can prevent an excessive force from being applied to a cutter element and prevent the cutter element from being damaged.

[Means for solving the problem]

In order to achieve the above object, the present invention employs the means described in the claims, and the operation is as follows.

[Action]

When the cutter element is operated by the driving device, the yarn is cut by the cutter element. In the above case, when the lump of yarn bites into the cutter element and the load on the cutter element increases, the spring member between the driving device and the cutter element absorbs an excessive driving force,
Excessive force transmission from the former to the latter is blocked. As a result, no excessive force is applied to the cutter element, and its breakage is prevented.

〔Example〕

Hereinafter, drawings showing an embodiment of the present application will be described. First
In the figure, reference numerals 1 to 8 denote constituent members of a known multi-axis sewing machine (for example, the same as that shown in JP-A-60-173156), wherein 1 is a bed, 2 is a needle plate, Is a shaft for operating the shuttle, and 4 is a shuttle. Reference numeral 7 denotes a yarn cutting device provided below the needle plate 2. Although not shown, a sewing machine arm is provided above the bed 1, and a plurality of needle bars which can be exchanged up and down are provided therein. At the lower end of each needle bar is provided a sewing needle 8 shown in FIGS. A multi-axis sewing machine having such a configuration has a plurality of heads (for example, 10
Head). Next, the yarn cutting device 7 will be described in detail with reference to FIGS. Thread cutting device 7
Is composed of a cutting mechanism 10, a driving device 9, and a transmission mechanism 21 for transmitting a driving force from the driving device 9 to the cutting mechanism 10. First, the cutting mechanism 10 will be described. Reference numerals 11 and 12 denote a pair of cutter elements, which are pivotally attached to the lower surface of the needle plate 2 using a pivot 13. Each of the cutter elements 11, 12 has a blade 11a, 11b and a blade 12a, 12b, respectively. Reference numeral 14 denotes a wave washer for pressing the cutter element 12 against the cutter element 11 so as to improve the mutual rubbing between the blades of the two cutter elements. 15, 16 are driven parts of each cutter element,
It is constituted by a driven piece attached to each. A lower thread pull-out piece 17 is provided below the pair of cutter elements 11 and 12, and is formed integrally with the cutter element 12 in this example.

Next, a solenoid is used as the driving device 9 as an example (an air or hydraulic cylinder may be used). Next, the transmission mechanism
21 will be described. Reference numeral 22 denotes a base frame, also called a mounting base, which is fixed to the bed 1. Reference numeral 23 denotes a transmission shaft rotatably mounted on a base frame 22, and an operation lever 24 is fixed to an upper end thereof. The operating lever 24 has engaging holes 25, 2 exemplified as an operating unit.
6 are provided, and the driven pieces 15, 16 are engaged with each other. Reference numeral 27 denotes a passive lever attached to the lower end of the transmission shaft 23, and a passive element 27a is pivotally connected to a free end. Reference numeral 29a denotes a driving rod which is reciprocated in the direction of the arrow in connection with the driving section of the driving device 9. The driving rod 29a penetrates a wide through hole 27b provided in the passive element 27a. Reference numerals 29b and 29b denote guide levers which are provided in parallel with each other.
It is pivotally connected to c, and the tip is pivotally connected to a driver described below. Each guide lever 29b is configured to have the same length so that the drive rod 29a can be moved in parallel. The length of the guide lever 29b is the same as that of the passive lever 27. 30a and 30b are driving elements for reciprocating and returning, respectively.
Both are fixed to the drive rod 29a. Reference numeral 30c denotes a spring member interposed between the passive element 27a and the driver 30a. As an example, a compression coil spring long enough to press the passive element 27a against the driver 30b is used. As the spring member, the second
A leaf spring 30d may be used as shown in the figure in the encircled box attached to the figure.

Next, 31 shows a needle thread distribution mechanism. 32 is a mounting frame in the mechanism, which is fixed to the bed 1. Reference numeral 33 denotes a driving device mounted on the mounting frame 32. As an example, a rotary solenoid in which a driving shaft 33a reciprocates is used. 34
The upper thread hooking piece is formed in a bifurcated shape, and its base is connected to the drive shaft 33a using a mounting bracket 35 so that it can enter and exit the shuttle 4.

Next, cutting of the lower thread and the upper thread by the thread cutting device 7 will be described with reference to the time chart of FIG. 9 and the operation explanatory diagrams of FIGS. 4A to 8, (A) is a plan view, (B) is a longitudinal sectional view in which the cloth, the needle plate, and the thread cutting device are broken at the position BB in FIG. 4 (A), and (C) is FIG. 5 is a longitudinal sectional view in which a cloth, a needle plate, and a thread cutting device are cut at a position CC in FIG. 4 (A). FIGS. 4 to 8 show the states at the respective points indicated by reference numerals 1 to 3 in FIG. In the process (a) in FIG. 9, the needle 8 moves up and down and the shuttle 4 rotates, and the cloth is laterally moved on the needle plate 2 as is well known. Sewing and embroidery (see FIG. 4B) with the thread 42 are performed as is well known. At this time, the cutter elements 11, 12 and the lower thread pull-out piece 17 in the thread cutting device 7 are in a preparation state as shown in FIG.

Next, when the above sewing is completed and the point of FIG. 9 (b) is reached,
The operation of the needle 8 and the shuttle 4 is stopped.

Next, the drive rod 9a reciprocates the drive rod 29a leftward as shown in FIG. 2 to cut the lower thread 42. Explaining the operation, the reciprocation of the drive rod 29a to the left causes the driver 30a
Pushes the passive element 27a via the spring member 30c, and the passive lever 27 rotates. The rotating power is transmitted to the operation lever 24 through the transmission shaft 23, and the lever 24 rotates clockwise in FIG. In the turning process, when the operation lever 24 first moves as indicated by the arrow in FIG. 4A, the members 11, 12, and 17 move as indicated by the arrows in FIG. 4A and FIG. Then, the lower thread pullout piece 17 first crosses below the needle hole 2a,
The lower thread 42 is pulled out from the shuttle 4 as shown in FIGS. 5 (A) and 5 (C). Next, as shown in FIG. 5 (C), the respective cutting edges of the blades 11a and 12a on the front side in the moving direction of the cutter elements 11 and 12 are aligned with the needle plate 2 and below the needle hole 2a. Then, the lower thread 42 is cut. Since the cutting is performed in this manner, the lower thread 42a of the lower thread 42 that is continuous with the cloth 40 is very short (for example, 5 mm). The lower thread 42b of the shuttle 4 of the lower thread 42
Has been drawn out in advance by the lower thread pulling-out piece 17 and is left long (for example, 60 mm). In addition, the lower thread 42 of the cut hook side
The b is removed by the lower thread pull-out piece 17 and hangs on the hook 4a as shown by an imaginary line in FIG. 5 (C). Eventually, when the drive rod 29a reaches the end point of reciprocation, the operation lever 24 reaches the position shown in the cutting device 7 on the left side of FIG.
11 and 12 are as shown in FIG.

After the lower thread is cut as described above, the upper thread is cut as follows. First, the driving device 33 of the upper thread distribution mechanism 31 is operated, and the upper thread hooking piece 34 enters the shuttle 4 as shown in FIG. In this state, the operation of the shuttle 4 and the needle 8 of the sewing machine is resumed, and the ninth operation is started.
The step shown in FIG. In the middle of this step, the needle 8 through which the upper thread 41 is passed enters the shuttle 4 as shown in FIG. The upper thread 41 is scratched by the sword of the shuttle 4 and moves around the shuttle 4 to form a loop as is well known. When the needle 8 eventually rises to the top dead center and reaches the point shown in FIG. 9 (d), the operation of the shuttle 4 and the needle 8 in the sewing machine is stopped. In this state, the loop 41d of the upper thread 41 is hooked on the upper thread hooking piece 34 as shown in FIG. After such a state, the driving rod 29a is moved by the driving device 9 to the second position.
It is returned to the right of the figure. The movement is transmitted from the driver 30b to the passive element 27a, and the passive lever 27 returns and rotates. The rotating force is applied to the operating lever 24 through the transmission shaft 23, whereby the lever 24 returns and rotates, and the cutter elements 11, 12 return in the returning direction as shown by arrows in FIGS. 7 (A) and 7 (C). Go to During the movement process, each cutter element 11, 12
As shown in FIG. 8, the cutting edges of the rear blades 11b and 12b are aligned below the needle hole 2a, and are connected to the cloth 40 of the upper thread 41 located below the needle hole 2a. The upper thread 41a on the side is cut. In this case, since the upper thread 41a is cut below the needle hole 2a, the upper thread 41c remaining on the cloth 40 side is extremely short as in the case of the lower thread. After the upper thread 41 has been cut as described above, the cutter elements 11, 12 return to the ready position again as shown in FIG.
The upper thread hooking piece 34 is also retracted outside the shuttle.

The cutting of the upper thread or the lower thread by the thread cutting device 7 as described above is performed simultaneously at each head because the driving rod 29a functions as an interlocking rod of the thread cutting device 7 at each head of the sewing machine.

The operations of the needle, the shuttle, and the thread cutting device as described above are performed in connection with each other using, for example, a known sequence control technique.

Next, in the case where the yarn is cut as described above,
As shown in FIG. 10, a case in which the lump 50 of the yarn bites into the cutting mechanism 10 will be described. The lump 50 is formed mainly by the upper thread 41 hanging on the lower side of the cloth 40 when the lateral movement of the cloth is small each time one stitch is sewn during sewing. When the lump 50 as described above is present, the lump 50 is pinched between the cutter element 11 and the lower thread pullout piece 17 as shown in FIG. 10 when the lower thread pullout piece 17 moves forward in the process of cutting the lower thread. The cutter element 11 and the lower thread pull-out piece 17 can no longer move. Therefore, the load on the passive lever 27 becomes very large. In such a state, the driving rod 29a
When the driver 30a pushes the passive element 27a via the spring member 30c, the passive element 27a does not move, and the spring member 30c is merely compressed as shown in the cutting device on the right side of FIG. . Therefore, no excessive force is applied to the cutter element 11 and the lower thread pull-out piece 17. Because of this,
Since the cutter elements 11 and 12 and the lower thread pull-out piece 17 in the cutting mechanism 10 are thin, they are most easily broken, but the breakage of them is prevented.

The above operation can be performed independently for each head since the spring member 30c as described above is provided in the thread cutting device 7 for each head in the multi-head sewing machine. Therefore, even if the above-described lump of thread 50 is bitten in any one of the heads, the thread cutting in the other head can be performed without any trouble.

In the above, the case of the cutting device having the lower thread pullout piece 17 has been described, but in the case of a normal cutting device having no lower thread pullout piece, the thread mass 50 is bitten between a pair of cutter elements. Therefore, breakage of the pair of cutter elements can be prevented.

Next, FIG. 11 shows a different embodiment of the present application, in which the structure of the transmission mechanism is partially different. In the figure, the passive element 27ae is provided with biasing means 52 for pressing the driving rod 29ae against the inner surface of the through hole 27be on the side remote from the rotation center of the passive lever 27e. The biasing means 52 includes a sphere 53 used to reduce the frictional force with the driving rod 29ae and a spring 54 for pressing the sphere 53 against the driving rod 29ae. Since such a biasing means 52 is provided in the thread cutting device 7e of each head sewing machine, the driving lever 2e is driven by the passive lever 27e of the thread cutting device 7e.
9e is guided to translate. In this case, the passive lever 27e becomes immovable in a cutting device in which the lump of the yarn is engaged, as in the cutting device 7e on the right side of the figure, but the urging means 5
Since 2 is retracted as shown in the figure, the parallel movement of the drive rod 29ae can be performed without any trouble, and other cutting devices can perform the cutting of the yarn without any trouble.

In addition, functionally considered to be the same or equivalent to those in the previous figure, the same reference numerals as those in the previous figure denote the same parts as in the previous figure.
And duplicated description is omitted.

[Effects of the Invention] As described above, according to the present invention, after sewing is completed, by operating the pair of cutter elements 11 and 12, the sewing thread connected to the cloth 40 can be cut. In the case of cutting the yarn, if the thread mass 50 bites into the cutter elements 11 and 12, the spring member 3 in the transmission mechanism between the driving device 9 and the cutter elements 11 and 12.
It is possible to prevent excessive force from being applied to the cutter element by absorbing excessive force by 0c, and it is possible to prevent breakage of the cutter element.

BRIEF DESCRIPTION OF THE DRAWINGS The drawings show an embodiment of the present invention, FIG. 1 is a partially cutaway perspective view showing a thread cutting device provided in a bed of a sewing machine, and FIG. 2 is a part of the thread cutting device. FIG. 3 is an exploded perspective view of the cutting mechanism, FIGS. 4 to 8 are operation explanatory views, FIG. 9 is a time chart, and FIG. 10 is a state in which a lump of thread is caught in the cutter element. FIG. 11 is a longitudinal sectional view, and FIG. 11 is a view similar to FIG. 2 showing a different example of the structure of the transmission mechanism. . 2. Needle plate, 2a Needle hole, 4 hook, 11, 12, cutter element, 30c spring member, 40 cloth, 41 upper needle, 42 lower thread.

Claims (1)

(57) [Claims] 1. A cutting mechanism having a pair of cutter elements for cutting a sewing thread is provided below a needle plate of a sewing machine, and a driving unit is connected to a driven part of the cutter element via a transmission mechanism. A threading device for a sewing machine, wherein the threading is performed by the cutter element by transmitting the movement of the driving unit to the driven part. A thread cutting device for a sewing machine, wherein a transmission mechanism between a driven part of the element and the driven part is configured to transmit through a spring member provided in the middle.