JPH08215466A - Thread cutting device for sewing machine - Google Patents

Abstract

PURPOSE: To dispense with the labor required in the setting work so far by automatically switching the thread cutting specifications for cutting both a needle thread and a bobbin thread and for cutting only the needle thread in response to the detection value of the frame shift quantity after a thread cut. CONSTITUTION: One of two thread cutting specifications for cutting both a needle thread and a bobbin thread and for cutting only the needle thread is selected depending on whether a bobbin thread relief lever 50 is located at the waiting position or the operating position when a moving knife 24 is operated. This thread cutting device for a sewing machine is provided with an actuator (solenoid) 40 for reciprocating the bobbin thread relief lever 50 between the waiting position and the operating position and the control means of the actuator 40. The control means compares the detection value of the frame shift quantity after a thread cut with the preset reference value prior to the thread cut, and it moves the bobbin thread relief lever 50 from the waiting position to the operating position with the actuator 40 when the detection value is the reference value or below.

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 capable of selectively switching between cutting of both the upper thread and the lower thread or cutting of only the upper thread in a sewing machine.

[0002]

2. Description of the Related Art A thread cutting device of this type is disclosed in, for example,
No. 67980 is disclosed. In the technology of this publication,
By rotating the lower thread retracting lever from the standby position to the operating position, it is possible to retract the lower thread out of the operation locus for thread cutting in the movable knife. That is, when the movable knife is rotated, if the bobbin thread retracting lever is held at the standby position, both the upper thread and the bobbin thread are cut, and the bobbin thread retracting lever is rotated to the operating position. Then, only the upper thread will be cut.

[0003]

However, in this prior art, the selection of thread cutting specifications such as cutting both the upper thread and the lower thread or cutting only the upper thread is individually performed at each thread cutting point of sewing (embroidery). Settings and sewing data (embroidery data)
When creating the, the selection data of the thread cutting specification is set in the data. In this case, for example, when the embroidery pattern is composed of a large number of partial patterns and there are a large number of thread cutting points, a great deal of labor is required for the setting work.
One problem to be solved by the present invention is to switch the thread cutting specifications such as cutting both the upper thread and the lower thread or cutting only the upper thread according to the detection value of the frame movement amount after the thread cutting. It's done automatically, eliminating the hassle of setting up to date. Another problem to be solved by the present invention is to allow a range of conditions for automatically switching thread cutting specifications.

[0004]

In order to solve the above-mentioned problems, the thread cutting device for a sewing machine according to the present invention is constructed as follows. The invention according to claim 1 is capable of retracting the bobbin thread from an operating locus for thread cutting in the movable knife by operating the bobbin thread retracting lever from its standby position to the operating position. Sewing machine that selects either of two thread cutting specifications, such as cutting both the upper thread and the lower thread or cutting only the upper thread, depending on whether the lower thread retracting lever is in the standby position or the operating position when And a control means for controlling the actuator, the control means for reciprocating the bobbin thread retracting lever between the standby position and the operating position. The detected value of the frame movement amount after the thread cutting is compared with a preset reference value, and when the detected value is equal to or less than the reference value or less than the reference value, the bobbin thread retracts by the actuator. The bar from the standby position is configured to actuate the operating position. According to a second aspect of the invention, in the thread cutting device for the sewing machine according to the first aspect, the reference value of the frame movement amount can be selected.

[0005]

According to the first aspect of the present invention, the switching between the two thread cutting specifications is automatically performed according to the detected value of the frame movement amount after the thread cutting. Therefore, there is no need to set the thread cutting specifications individually at each thread cutting point for sewing and to insert the selection data of thread cutting specifications into the sewing data when creating the sewing data. According to the second aspect of the present invention, by selecting the reference value of the frame movement amount, it is possible to have a wide range of conditions for automatically switching the thread cutting specifications.

[0006]

Embodiments of the present invention will now be described with reference to the drawings. The following embodiments apply the present invention to a thread cutting device of an embroidery sewing machine. 1 is a plan view showing a main mechanism of a sewing machine arranged below a sewing machine head, FIG. 2 is a side view of FIG. 1, and FIG. 3 is a sectional view of the same seen from the front of FIG. As shown in these drawings, a needle plate 12 is fixed to the upper surface of the hook base 10, and a hook 14 is arranged below the needle plate 12. As is well known, the hook 14 includes an inner hook and an outer hook. The outer hook is rotatably supported by the hook base 10 and receives a rotational force from the hook drive shaft 16 to rotate relative to the inner hook. It is supposed to do.

As is apparent from FIGS. 1 and 3, the needle plate 1
A fixed knife 22 and a movable knife 24 are provided on the knife base 20 fixed to the kettle base 10 between the two and the kettle 14. The fixed knife 22 is fixed to the knife base 20, and the movable knife 24 is fixed to an end of a knife shaft 26 rotatably supported by the knife base 20. This female shaft 26 is attached to the base 10
It is adapted to be reciprocally rotated together with the movable knife 24 in conjunction with the reciprocating slide of the knife driving shaft 28 disposed below. By rotating the movable knife 24, it is possible to cut the thread (both the upper thread and the lower thread or only the upper thread) in cooperation with the fixed knife 22 as described later.

FIG. 4 is a perspective view showing a part of FIG. 1, and FIG.
Similarly, a part of FIG. 1 is shown enlarged. As is clear from these drawings, an actuator bracket 30 and a lever bracket 32 are fixed to the pot base 10 by a plurality of bolts 36, respectively. The actuator bracket 30 has a mounting portion 31 that is bent rearward on a side portion of the pot base 10,
Here, a solenoid 40 used as an actuator for actuating (turning) a bobbin thread retracting lever 50 described later.
Has been fixed. Note that this actuator may use an air cylinder or a motor instead of the solenoid 40.

As shown in FIGS. 4 and 5, a headed pin 63 is fixed to the front surface of the actuator bracket 30, and a drive lever 60 is mounted on the shaft of the headed pin 63.
Is movably supported in the front-back direction. Moreover, buffer rings 64 and 65 are provided on the shaft of the headed pin 63 between the head and the drive lever 60 and between the front surface of the actuator bracket 30 and the drive lever 60, respectively. One end (right end) of the drive lever 60 is connected to the tip of the plunger 42 of the solenoid 40 by a fixing screw 62. A connecting pin 66 protruding upward is fixed to the other end of the drive lever 60.

The front surface of the solenoid 40 and the drive lever 6
A spring 44 is provided between the spring 42 and 0, and the plunger 42 is urged by the elastic force of the spring 44 so as to be pushed forward together with the drive lever 60. At this time, the drive lever 60 is received by the head of the headed pin 63 via the buffer ring 64 as shown in FIG. The entire solenoid 40 and the plunger 42 and a part of the drive lever 60 are covered with a cover 46 as shown by the phantom lines in FIGS.

On the other hand, a vertical lever shaft 52 is rotatably supported on the lever bracket 32. The base end of the bobbin thread retracting lever 50 is fixed to the upper end of the lever shaft 52 on the upper surface side of the lever bracket 32. The base end of the interlocking arm 56 is fixed to the lower end of the lever shaft 52 on the lower surface side of the lever bracket 32. The tip end of this interlocking arm 56 is bifurcated, and the connecting pin 6 of the drive lever 60 is there.
6 is engaged so as to be relatively rotatable.

When the drive lever 60 is in the position pushed forward as described above by the elastic force of the spring 44, the bobbin thread retracting lever 50 is held at the standby position shown in FIG. There is. When the solenoid 40 is turned on (excited), the drive lever 60 moves backward together with the plunger 42 against the elastic force of the spring 44, and the drive lever 60 causes the front surface of the actuator bracket 30 to move the buffer ring 65. Will be accepted through.

FIG. 6 is a block diagram showing a state in which the solenoid 40 is turned on in correspondence with FIG. When the drive lever 60 is retracted as shown in this drawing, the lower thread retracting lever 50 is rotated from the standby position to the operating position shown in FIG. 6 and is held in that state in conjunction with this. When the solenoid 40 is turned off (non-excited), the drive lever 60 is pushed forward again by the elasticity of the spring 44, and the bobbin thread retracting lever 50 also returns to the standby position.

7 and 8 are enlarged views showing the range of rotation of the movable knife 24 together with other related members. As shown in these drawings, the movable knife 24 is reciprocally rotated between a solid line position and an imaginary line position in association with the reciprocating drive of the knife drive shaft 28. The movable knife 24 is rotated (forward) from the solid line position to the virtual line position based on a predetermined thread cutting signal, so that the projecting end 24a of the needle thread 70 is connected to the cloth side to be sewn. The thread 70a and the needle side upper thread 70b connected to the sewing needle are advanced to separate them. Following this, the movable knife 24 is rotated (returned) from the imaginary line position to the solid line position, so that in FIG.
0a and the bobbin thread 80, and in FIG.
Only a is hooked on the movable knife 24 so that the fixed knife 2
It is transported to position 2 and cut. The tip 24a
A region sandwiched between the rotation locus of No. 2 and the rotation locus of the protruding end 24b on the opposite side is an operation locus for thread cutting in the movable knife 24.

In the yarn cutting apparatus of this embodiment, the movable knife 24 moves in the counterclockwise direction on the basis of the yarn cutting signal to divide the yarn, and then the movable knife 2 is moved.
This is a type in which thread cutting is performed by returning 4 to the clockwise direction. On the other hand, there is also a type of thread cutting device in which the movable knife 24 is moved in the clockwise direction in the opposite direction to perform thread separation, and the thread is cut in the counterclockwise direction to return the thread. The present invention can be applied to any of the formats.

The thread cutting signal is transmitted at the stop code and end code of the embroidery data. The stop code is set to the end point of the embroidery of each partial pattern forming the entire embroidery pattern or the point at which it is necessary to stop the color change of the needle thread 70. The end code is the end code of the entire embroidery pattern. It is set to a point. When thread cutting is performed based on the stop code, for example, the distance from the embroidery end point of the partial pattern to the embroidery start point of the next partial pattern, that is, the frame movement amount of the embroidery frame (not shown) Both the cloth side upper thread 70a and the lower thread 80 are cut as described below (hereinafter referred to as "upper and lower thread cutting").
It is also necessary to select one of two thread cutting specifications such as cutting only the cloth side upper thread 70a (hereinafter also referred to as "upper thread cutting"). If thread cutting is performed based on the above end code, be sure to perform "upper and lower thread cutting".
Is.

Next, each of the two thread cutting specifications will be described. First, in the case of “upper and lower thread cutting”, the solenoid 40 remains off and the lower thread retracting lever 50 is held at its standby position. Here, the movable knife 24 is reciprocally rotated between the solid line position and the imaginary line position in FIG. 7, whereby both the cloth side upper thread 70a and the lower thread 80 are cut as described above. On the other hand, in the case of "needle cutting"
The solenoid 40 is turned on to rotate the bobbin thread retracting lever 50 from the standby position to the operating position. As a result, the bobbin thread 80 is hooked on the tip of the bobbin thread retracting lever 50 and retracts out of the operating locus of the movable knife 24 as shown in FIG. In this state, the movable knife 24 reciprocally rotates between the solid line position and the imaginary line position in FIG. 8, whereby only the cloth side upper thread 70a is cut.

The solenoid 40 is on / off controlled by a control means (computer) for performing frame movement and various other automatic controls based on the embroidery data, and therefore, selection of two thread cutting specifications is automatically performed. Will be done. That is, the control means detects the amount of frame movement from the embroidery end point of the partial pattern for which the stop code is set in the embroidery data to the embroidery start point of the next partial pattern prior to thread cutting, and the detected value And a reference value set in advance. As a result, when the detected value is, for example, the reference value or more, the solenoid 40 is kept off, and “upper and lower thread cutting” is selected. On the other hand, when the detected value is, for example, less than the reference value, the solenoid 40 is turned on and "needle cutting" is selected.

The above-mentioned detected value is obtained by pre-reading the frame movement amount after thread cutting from the embroidery data prior to thread cutting. It should be noted that the composite value of the frame movement amounts in both the X and Y directions may be calculated and used as the detection value, but here, in order to simplify the processing, one of the frame movement amounts in both the X and Y directions having the larger absolute value is detected. It has a value. The reference value may be arbitrarily set according to the embroidery conditions and the like, and in this embodiment, it is possible to select four stages of "5 mm", "10 mm", "15 mm" and "20 mm". There is.

FIG. 9 shows an example of the embroidery pattern 100. The automatic switching of the thread cutting specifications will be described with reference to this drawing. The embroidery pattern 100 has four partial patterns 1
It is composed of 01, 102, 103 and 104. The points a, b, of the three partial patterns 101, 102, 103
c is the respective embroidery start point and the embroidery end point, and the stop code is set at the embroidery end point as described above. The point d of the partial pattern 104 is the embroidery start point and the embroidery end point, and the embroidery pattern 100
Since it is also the end point of the entire embroidery, the end code is set at the end point.

Now, it is assumed that "10 mm" is selected and set as the reference value, and that each of the points a to d is set.
Has the following positional relationship. a → b; X = + 6 mm, Y = -8 mm b → c; X = + 30 mm, Y = + 8 mm c → d; X = -20 mm, Y = -40 mm

Therefore, the thread cutting specifications based on the above stop code are as follows. (1) In “a → b”, the detected value is 8 mm and less than the reference value (10 mm), so the solenoid 40 is turned on and “upper thread cutting” is selected. (2) In the case of "b → c", the detected value is 30 mm and is equal to or larger than the reference value, so that the solenoid 40 is kept off and "upper and lower thread cutting" is selected. (3) In "c → d", since the detected value is 40 mm and is equal to or greater than the reference value, the solenoid 40 is held off and "cutting of the upper and lower threads" is selected. By selecting the above reference value, it is possible to change the condition for switching the thread cutting specifications. For example, the reference value is "5
In the case of "mm", the detected value (8 mm) becomes equal to or larger than the reference value in "a → b", and "upper and lower thread cutting" is selected.

[0023]

According to the present invention, since the thread cutting specifications such as cutting both the upper thread and the lower thread or cutting only the upper thread are automatically changed, the labor required in the conventional setting work is eliminated. It becomes unnecessary and simplifies preparation work such as embroidery sewing. Also, if you can select the reference value of the frame movement amount,
This is convenient because it allows a wide range of conditions for automatically switching thread cutting specifications.

[Brief description of drawings]

FIG. 1 is a plan view showing a main mechanism of a sewing machine arranged below a sewing machine head.

FIG. 2 is a side view of FIG.

3 is a sectional view of the same as seen from the front of FIG. 1. FIG.

FIG. 4 is a perspective view showing a part of FIG.

FIG. 5 is a plan view showing a part of FIG. 1 in an enlarged manner.

FIG. 6 is a plan view showing a state in which a solenoid is turned on in correspondence with FIG. 5.

FIG. 7 is an enlarged view showing a rotation range of a movable knife in a state in which both the upper thread and the lower thread are cut.

FIG. 8 is an enlarged view showing a rotation range of the movable knife in a state in which only the upper thread is cut.

FIG. 9 is an explanatory diagram showing an example of an embroidery pattern.

[Explanation of symbols]

 24 Movable knife 40 Solenoid (actuator) 50 Lower thread retract lever 70 Upper thread 80 Lower thread

Claims (2)

[Claims] 1. A bobbin thread can be retracted from an operation locus for thread cutting in a movable knife by operating a bobbin thread retracting lever from its standby position to an operating position.
Depending on whether the bobbin thread retracting lever is in the standby position or the operating position when the movable knife is operating, either one of two thread cutting specifications is selected, such as cutting both the upper thread and the lower thread or cutting only the upper thread. A thread cutting device for a sewing machine, comprising: an actuator for reciprocating the bobbin thread retracting lever between the standby position and the operating position; and a control means for the actuator, the control means Prior to this, the detected value of the frame movement amount after thread cutting is compared with a preset reference value, and when the detected value is less than or equal to the reference value or less than the reference value, the lower thread retract lever is moved from the standby position by the actuator. A thread cutting device for a sewing machine, which is configured to be operated to an operating position. 2. The thread cutting device for a sewing machine according to claim 1, wherein a reference value of the frame movement amount is selectable.