JPH06210085A - Thread snap detector of sewing machine - Google Patents

Abstract

PURPOSE:To obtain a detector of thead snap of a sewing machine, which is capable of detecting snap of a needle thread, etc., without deteriorating sewing conditions. CONSTITUTION:A thread snap detector 12 consists of a vibrating plate 17 which is held inside a nearly U-shaped holder 13 via cushioning materials 16 and a piezoelectric element 18 which is attached on the surface of the vibrating plate 17. The holder 13 is mounted between a tread spool of a head and a thread tension regulator of a sewing machine main body. Vibrations which are produced by a needle thread 8 when it passes through thread holes 17A are detected as electric signals via the piezoelectric element 18, so that snapping of the thread can be detected without a storing sliding of the needle thread 8 on the vibrating plate 17. The thread snap detector 12 can be used as a thread guard as well.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thread breakage detecting device for a sewing machine which is preferably used for detecting a thread breakage in a sewing machine for embroidery.

[0002]

2. Description of the Related Art Generally, a sewing machine main body having a drive source for rotationally driving a spindle, a head portion provided on the sewing machine main body for reciprocating a driving portion by the rotation of the spindle, and a reciprocating motion for the head portion. And a needle shaft that is driven upward and downward by a drive unit of the head unit, and an embroidery needle as a sewing machine needle that is attached to the tip end side of the needle shaft and through which an upper thread (embroidery thread) is inserted. In order to supply the upper thread to the embroidery needle, an upper thread storage section that stores the upper thread in a wound state and a tension provided to the upper thread that is provided in the head section and that is supplied to the embroidery needle from the upper thread storage section. A thread tension to be given, and a thread hook inserted between the thread tension and the needle thread storage portion, attached to the head portion, and through which an intermediate portion of the needle thread guided from the needle thread storage portion to the thread tension is inserted. , Which is provided on the sewing machine main body under the head part, holds the embroidery cloth in a stretched state A frame moving mechanism for moving the embroidery frame relative to the head portion, and the frame moving mechanism and the head provided on the sewing machine main body based on embroidery data so as to realize an embroidery pattern on the embroidery cloth. A sewing machine for embroidery, which is composed of a control device that operates a drive unit of the machine, is known.

In this type of embroidery sewing machine, while the main shaft is rotated by the drive source, the drive section of the head section is reciprocated,
The drive unit drives the embroidery needle up and down through the needle shaft, and the frame moving mechanism moves the embroidery frame holding the embroidery cloth in a stretched state in the X-axis and Y-axis directions. The needle is moved with respect to the embroidery cloth, and a needle thread of a desired color is sewn on the embroidery cloth to realize a desired embroidery pattern.

In this case, the embroidery needle reaches the bottom dead center from the top dead center each time the main shaft makes one rotation, and is stabbed into the embroidery cloth. While reaching the dead point, the upper thread is sewn to the embroidery cloth and is withdrawn from the embroidery cloth. However, if a thread breakage of the upper thread occurs during the movement of the embroidery needle, the creation of the embroidery pattern is interrupted. This is detected by a thread breakage sensor or the like, and the surrounding operator or the like breaks the upper thread or the like. Is notified.

As a thread breakage sensor of this type,
A leaf spring as an actuator having an insertion portion through which a needle thread is inserted, which is provided between a balance and a sewing needle that are swung up and down by a drive unit of the head unit, and vibration of the leaf spring It consists of a piezoelectric body that converts into an electric signal. By detecting the vibration when the upper thread slides through the insertion part of the leaf spring, the piezoelectric body detects whether the upper thread breaks or not. It is known, for example, from Japanese Patent Application Laid-Open No. 63-242299, etc. to determine whether or not it is present.

[0006]

By the way, in the above-mentioned thread breakage detecting device for a sewing machine according to the prior art, a thread breakage sensor is provided between the balance and the sewing machine needle, and the upper thread is strongly attached to the leaf spring of the thread breakage sensor. Since it slides, the sliding resistance between the needle thread and the leaf spring of the thread breakage sensor may become excessive, resulting in an excessive load being applied to the needle thread, making it smooth for the sewing machine needle. However, there is a problem that the sewing condition is deteriorated.

When a thread breakage occurs below the needle tip of the sewing machine needle, and the needle thread moves up and down together with the balance with the upper thread still caught in the thread hole of the needle tip, ,
When the balance is driven upward, tension is applied to the upper thread between the balance and the sewing needle, so the thread breakage sensor provided between the balance and the sewing machine needle detects the thread breakage in this case. However, there is a problem that it is difficult to detect the thread breakage with high accuracy.

On the other hand, as another conventional technique, a thread breakage sensor of the type in which an electrical contact is provided on a thread take-up spring of a thread tension is known, but in this case, it is necessary to use the hand of the operator when threading the thread. Poor contact may occur due to sweat, thread dust, or the like, and it is difficult to detect when the thread breaks below the needle tip.

The present invention has been made in view of the above-mentioned problems of the prior art. The present invention is directed to a sewing machine capable of detecting thread breakage of a needle thread or the like with high accuracy without deteriorating the sewing tone. An object is to provide a yarn breakage detection device.

[0010]

In order to solve the above problems, the present invention provides a sewing machine main body, a head portion provided on the sewing machine main body for reciprocating a sewing machine needle, and a sewing machine needle of the head portion. An upper thread storage part for storing the upper thread in a wound state to supply the thread; a thread tensioner provided in the head section for applying tension to the upper thread supplied from the upper thread storage part to the sewing machine needle; The upper thread, which is located between the thread tensioner and the upper thread storage section and is attached to the head section, and which is guided from the upper thread storage section to the thread tensioner, is inserted so that the upper thread slides based on the sliding movement of the upper thread. A configuration that includes a yarn breakage sensor that detects a yarn breakage is adopted.

In this case, the thread breakage sensor is provided with a mounting bracket which is mounted on the head portion, and a needle thread which is provided on the mounting bracket through a cushioning material and which is inserted through a plurality of threading holes. It is preferable that the diaphragm includes a vibrating plate that vibrates according to the present invention, and a piezoelectric body that is provided on the vibrating plate and that detects the yarn breakage with or without vibration by outputting the vibration of the vibrating plate as an electric signal.

[0012]

With the above construction, since the thread breakage sensor is provided between the thread tensioner and the upper thread storage portion at a position farther from the sewing machine needle than the thread tension in the head section of the sewing machine, the needle movement of the sewing machine needle is possible. Occasionally, an extra load is not applied to the upper thread between the sewing machine needle and the thread tension, and the movement amount (sliding amount) of the upper thread can be detected without impairing the sewing tone. In addition, when thread breakage occurs below the needle tip, or when the lower thread runs out, there is no force to draw the upper thread between the thread tension and the upper thread storage section. Since the movement of is also stopped, this can be detected as a thread break.

Further, if the mounting bracket for the thread breakage sensor is mounted on the head portion of the sewing machine and the diaphragm is provided on the mounting bracket via the cushion material, the vibration from the head portion is prevented from being transmitted to the diaphragm. It is possible to vibrate the diaphragm only when the upper thread slides through the threading holes of the diaphragm. The presence or absence of yarn breakage can be detected by the piezoelectric body based on the vibration of the diaphragm, and it is not necessary to strongly slide the diaphragm of the yarn breakage sensor with respect to the needle thread.

[0014]

Embodiments of the present invention will be described in detail below with reference to FIGS.

First, FIGS. 1 to 3 show a first embodiment of the present invention.

In the figure, reference numeral 1 denotes a sewing machine main body, and the sewing machine main body 1 is generally composed of a base 2 and a head portion 3 which will be described later and is provided on the base 2.

Reference numeral 3 denotes a head portion. The head portion 3 is fixed to the base 2 and has a large end portion 3A, and the head portion 3 is bent in a substantially L-shape at an upper portion of the large end portion 3A, and is substantially the base 2. Arm part 3B extending in parallel
And a small end portion 3C which projects downward from the tip end side of the arm portion 3B and faces an embroidery frame (not shown) on the base 2.

Reference numeral 4 denotes a flywheel provided on the base end side of the arm portion 3B of the head portion 3. The flywheel 4 is connected to a main shaft extending in the arm portion 3B of the head portion 3, and this main shaft is connected via a belt or the like. The motor is provided as a drive source in the base 2 (both not shown) so as to be rotationally driven.

A drive unit (not shown) is provided in the small end portion 3C of the head portion 3 for converting the rotation of the main shaft into upward and downward reciprocating motions, and the needle protruding from the small end portion 3C toward the base 2 side. The shaft 5 and the sewing needle 6 are driven up and down by this drive unit.

Reference numeral 7 denotes a thread winding as an upper thread storage portion provided on the head portion 3, and an upper thread 8 as an embroidery thread is stored in a wound state in the thread winding 7, and the upper thread 8 is a sewing needle. When the needle 6 is moved, it is supplied toward the sewing machine needle 6.

Reference numerals 9 and 9 denote thread tensioners provided on the head portion 3. The thread tensioners 9 and 9 are arranged between the thread winding 7 and a thread tensioner 10 which will be described later. Is applied to the upper thread 8.

Reference numeral 10 denotes a thread tensioner provided on the head portion 3. The thread tensioner 10 is provided with a so-called thread take-up spring (not shown) for applying tension to the upper thread 8 by hooking the upper thread 8 on the outer peripheral side. In order to replenish the upper thread 8 guided from the bobbin winding 7 to the side of the balance 11 which will be described later, low friction thread feeding is performed. Then, the thread tensioner 10 gives a tension of, for example, about 30 to 50 g to the upper thread 8, and when the upper thread 8 is pulled by the sewing machine needle 6 or the like beyond this tension, the upper thread 8 is moved to the balance 11 side. I try to allow it to be fed.

Reference numeral 11 denotes a balance which is swung up and down by a drive unit of the head unit 3. The balance 11 moves up and down in synchronization with the sewing machine needle 6, and when it is driven downward, the sewing machine needle is shown. 6 and a slight slack is given to the upper thread 8 and the upper thread 8 is fed to the sewing machine needle 6 side. When the balance 11 is driven upward, tension is applied to the upper thread 8 between the stitches (not shown) formed on the embroidery cloth by the sewing machine needle 6 and the thread tension 10 and the like. Occasionally, the seam is tightened and the upper thread 8 is fed out.

Reference numeral 12 denotes a thread break sensor which is provided between the spool 7 and the thread tension member 10 and which is provided on the arm 3B of the head section 3. The thread break sensor 12 is a holder described later as shown in FIG. It is roughly composed of 13, a vibration plate 17, and a piezoelectric body 18.

Reference numeral 13 denotes a holder serving as a mounting bracket. The holder 13 is formed into a substantially U shape having an upper plate portion 13A, a lower plate portion 13B and a side plate portion 13C by bending a thin metal plate such as brass. Has been formed. Here, the side plate portion 13C of the holder 13 has screws 1 as shown in FIG.
An attachment pipe 15 for attaching the holder 13 to the head portion 3 via 4 is fixed.

Reference numerals 16, 16, ... Denote cushion materials provided on the lower side surface of the upper plate portion 13A and the upper side surface of the lower plate portion 13B, which are located at both ends of the holder 13, respectively. Is formed into a rectangular parallelepiped shape having a width dimension of 6 mm before and after, and a thickness dimension of about 2 mm from an elastic material such as sorbosein and neoprene sponge rubber.
It is attached by an adhesive or the like to support the diaphragm 17 inside.

A diaphragm 17 is sandwiched between the upper and lower plate portions 13A and 13B of the holder 13 by upper and lower cushion members 16, 16, ... And is attached to the holder 13 by an adhesive or the like. The vibrating plate 17 is formed as a substantially rectangular flat plate from a thin metal plate such as brass, and has three threading holes 17A, 17A, 17A, 17A, which are spaced apart in the left-right direction from the front end side protruding from the holder 13. ... has been drilled. Then, the upper thread 8 is inserted into each thread threading hole 17A as shown by the alternate long and short dash line in FIG. When the upper thread 8 is supplied to the 6 side,
7 vibrates the diaphragm 17 up and down by sliding on the upper and lower surfaces.

Reference numeral 18 denotes a piezoelectric body which is provided on the surface of the vibration plate 17 by being separated from the respective threading holes 17A rearward by means such as adhesion. The piezoelectric body 18 is, for example, lead zirconate titanate ( PZT) and other thin plate-shaped piezoelectric ceramics 18A, and electrodes 18B and 18B formed by means such as vacuum deposition on the upper and lower surfaces of the piezoelectric ceramics 18A. When applied, an electromotive force is generated between each electrode 18B.
The piezoelectric body 18 integrally vibrates when the vibrating plate 17 vibrates, and an electric signal (detection signal) corresponding to the vibration at this time is not shown from the lead wire 19 provided on each electrode 18B. Output to the control device. here,
This control device is configured to include an operational amplifier and the like, and is provided in the arm portion 3B of the head portion 3 near the yarn breakage sensor 12.

This embodiment has the structure described above. When the main shaft is rotated by the motor and the drive unit of the head unit 3 is reciprocated, the drive unit drives the sewing needle 6 up and down. By moving the sewing needle 6 with respect to the embroidery cloth, the needle thread 8 of a desired color is sewn on the embroidery cloth to realize a desired embroidery pattern.

Each time the sewing machine needle 6 forms a stitch on the embroidery cloth, the upper thread 8 is supplied from the thread winding 7 to the sewing machine needle 6 side via the thread tensioner 10. At this time, the upper thread 8 is vibrated. The vibrating plate 17 is vibrated up and down by sliding on the upper and lower surfaces of 17 and in the threading hole 17A. Therefore, the piezoelectric body 18 provided on the vibrating plate 17 is electrically driven based on the vibration at this time. A signal is output to the control device, and the control device determines on the basis of this electric signal that the needle thread 8 is properly fed out.

In this case, the balance 11 of the head part 3 repeats the upward and downward movements together with the sewing machine needle 6, and the tension of the upper thread 8 is accompanied by the upward and downward movements of the balance 11 between the sewing machine needle 6 and the thread tension member 10. The tension of the upper thread 8 reaches a peak value when the balance 11 reaches the top dead center. Then, when the tension of the upper thread 8 at this time exceeds, for example, about 30 to 50 g, the upper thread 8 is paid out from the thread tensioner 10, and the vibration of the thread breakage sensor 12 is generated between the thread tensioner 10 and the thread winding 7. Since it moves via the plate 17 or the like, it is possible to detect whether or not the upper thread 8 is properly fed out based on the vibration of the diaphragm 17.

On the other hand, when the upper thread 8 breaks midway, or when thread breakage occurs below the needle tip, or when the lower thread (not shown) runs out and the movement of the upper thread 8 is interrupted, the thread winding 7 And the thread tension member 10 do not slide the needle thread 8 in the threading hole 17A of the diaphragm 17, etc., the vibration of the diaphragm 17 is stopped, and the output of the electric signal from the piezoelectric body 18 is interrupted. Therefore, the control device determines that the upper thread 8 or the like has broken, and notifies the operator or the like of the thread break of the upper thread 8 or the like.

Thus, in the present embodiment, the thread breakage sensor 1
2 is located between the bobbin winder 7 and the thread tension 10, and the head portion 3
Since it is provided on the arm portion 3B of the
It is not necessary to provide a thread break sensor or the like between the sewing machine needle 6 and the sewing machine needle 6, and it is possible to prevent an extra load from being applied to the needle thread 8 between the sewing machine needle 6 and the thread tension member 10 when the sewing machine needle 6 is moved. The thread breakage of the upper thread 8 and the like can be detected without impairing the sewing condition. Even when thread breakage occurs below the needle tip or when the bobbin thread disappears, the movement of the upper thread 8 is interrupted, and this can be reliably detected as a thread break.

Further, the thread breakage sensor 12 is provided in the diaphragm 1 when the upper thread 8 moves in the threading holes 17A of the diaphragm 17.
7 is vibrated, and this vibration is detected as an electric signal via the piezoelectric body 18. Therefore, the diaphragm 17 of the thread break sensor 12 is strongly pressed against the upper thread 8 as compared with the prior art. It is not necessary to detect the thread breakage of the upper thread 8 and the like with high sensitivity. Then, by supporting the diaphragm 17 in the holder 13 via the cushion members 16, 16, ..., It is possible to effectively prevent the vibration from the head portion 3 side from being transmitted to the diaphragm 17, and thus the upper thread Only the vibration when 8 slides on the diaphragm 17 can be transmitted to the piezoelectric body 18 via the diaphragm 17.

Further, since the yarn breakage sensor 12 has a contactless structure using the piezoelectric body 18, it is possible to perform stable yarn breakage detection without being affected by yarn dust or dust. Then, the bobbin 7 is also used as the thread hook of the sewing machine according to the prior art.
Since the thread break sensor 12 is provided between the thread tension controller 10 and the thread tension controller 10, it is not necessary to provide another thread hook, and the thread break sensor 12
A control device including an operational amplifier and the like can be built in the arm portion 3B of the head portion 3 in close proximity to.

Next, FIGS. 4 and 5 show a second embodiment of the present invention. The feature of this embodiment is that a holder as a mounting bracket is formed in an L-shaped cross section, and a vibration plate is attached to the holder. It was installed on the upper surface side with a cushion material. In this embodiment, the same components as those of the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

In the figure, reference numeral 21 denotes a thread breakage sensor according to this embodiment, and the thread breakage sensor 21 is substantially the same as the thread breakage sensor 12 described in the first embodiment, and a holder 2 to be described later.
2, the piezoelectric body 18, and the diaphragm 24.

Reference numeral 22 denotes a holder, which is composed of an upper plate portion 22A and a side plate portion 22B bent from the rear end side of the upper plate portion 22A into a substantially L shape.

Reference numerals 23 and 23 denote a pair of cushion members provided on the upper plate portion 22A of the holder 22 so as to be spaced apart left and right, and each cushion member 23 is the cushion member 16 described in the first embodiment. Similarly to the above, each cushion material 23 is formed from an elastic material such as sorbosein into a rectangular parallelepiped shape.
For example, the thickness dimension is 3mm before and after, the width dimension is 2mm before,
Later formed. The cushion members 23 are fixed to the upper surface side of the vibration plate 24 with an adhesive or the like, and the vibration plate 24 is supported by the upper plate portion 22A of the holder 22 with a gap.

Reference numeral 24 denotes a vibration plate. The vibration plate 24 has substantially the same structure as that of the vibration plate 17 described in the first embodiment, but the vibration plate 24 is separated from the left and right sides by two. Individual threading holes 24A, 24A are formed.

The yarn breakage sensor 21 according to the present embodiment is constructed as described above. The yarn breakage sensor 21 is located between the bobbin winder 7 and the thread tensioner 10 as in the first embodiment, and the head portion 3 is provided. Attached to the upper thread 8 as shown by the alternate long and short dash line in FIG.
Is inserted into each threading hole 24A in the upward and downward directions, and the upper thread 8 is slid in each threading hole 24A of the diaphragm 24 to detect the thread breakage of the upper thread 8.

According to this embodiment having the above-described structure, substantially the same operation and effect as those of the first embodiment can be obtained. However, particularly in this embodiment, the upper surface of the diaphragm 24 is provided with the cushion members 23. Since the upper plate portion 22A of the holder 22 is supported by being separated by a predetermined dimension, the diaphragm 2
4 can be effectively compensated for the vibration of the upper thread 8 by the sliding of the upper thread 8, the detection sensitivity of the piezoelectric body 18 can be increased, and each threading hole 24A of the diaphragm 24 is two. As a result, the sliding resistance of the upper thread 8 can be reduced.

Next, FIG. 6 shows a third embodiment of the present invention. In this embodiment, the same components as those of the second embodiment are designated by the same reference numerals and the description thereof will be omitted. To do
The feature of this embodiment is that the cushion member 31, 31 is provided on the upper plate portion 22A of the holder 22 so as to be spaced apart to the left and right, and the diaphragm 24 and the piezoelectric body 18 are supported by the holder 22 via the cushion member 31. There is a configuration to let.

Here, although each cushion material 31 is formed in substantially the same manner as the cushion material 16 described in the first embodiment, each cushion material 31 has a thickness of 3 m.
The width dimension is 6 mm before and after m.

In this way, this embodiment, which is constructed in this way, can also achieve substantially the same operational effects as the second embodiment.

In the first embodiment, the diaphragm 17
The case where three threading holes 17A are provided in the above has been described as an example, but the present embodiment is not limited to this, and may be two, for example, and the second and third embodiments. In the above description, the case where the diaphragm 24 is provided with two threading holes 24A has been described as an example, but the number may be three, for example.

Further, in each of the above-described embodiments, the bobbin winding 7 as the upper thread storage portion is provided on the head portion 3, but the present invention is not limited to this, and the head portion 3 is provided above the base 2, for example. You may make it provide the upper thread storage part, such as the bobbin 7, at the position spaced apart from.

Further, in each of the above-mentioned embodiments, the thread break sensor 12 (21) is composed of the holder 13 (22), each cushion member 16 (23, 31), the diaphragm 17 (24), the piezoelectric body 18, and the like. However, the present invention is not limited to this, and for example, the diaphragm 17 (24) may be omitted and the piezoelectric body 18 may be attached to the holder 13 (22) via a cushion material or the like. A type of thread break sensor may be used.

[0049]

As described in detail above, according to the present invention, an upper thread storage portion in which an upper thread is stored in a wound state, and a thread for applying tension to the upper thread supplied from the upper thread storage portion to the sewing machine needle. The thread breakage sensor is attached to the head portion, and the needle thread guided from the needle thread storage section to the thread tension is inserted into the thread breakage sensor, so that the thread breakage sensor moves based on the sliding movement of the needle thread. Since it is configured to detect breakage, it is possible to detect thread breakage of the upper thread, etc. without impairing the sewing condition, and even if thread breakage occurs below the needle tip, or even if the lower thread runs out, the upper thread This can be detected as a thread break by stopping the movement of the thread.

Further, if the mounting bracket of the thread breakage sensor is mounted on the head portion of the sewing machine and the diaphragm is provided on the mounting bracket via the cushion material, the vibration from the head portion is prevented from being transmitted to the diaphragm. It is possible to vibrate the diaphragm only when the upper thread slides through the threading holes of the diaphragm. The presence or absence of yarn breakage can be detected by the piezoelectric body based on the vibration of the diaphragm, and it is not necessary to strongly slide the diaphragm of the yarn breakage sensor with respect to the needle thread.

Further, by mounting the thread breakage sensor between the thread tension and the upper thread storage portion, the thread breakage sensor can be used as a thread hook, and the thread breakage sensor can be brought close to a control device normally provided in the head portion. Various effects such as disposition of the break sensor can be achieved.

[Brief description of drawings]

FIG. 1 is a front view showing a sewing machine provided with a thread breakage sensor according to a first embodiment of the present invention.

2 is an enlarged perspective view showing a thread breakage sensor in FIG. 1. FIG.

3 is a sectional view taken along the line III-III in FIG.

FIG. 4 is an enlarged perspective view showing a yarn breakage sensor according to a second embodiment of the present invention.

5 is a sectional view taken along the line VV in FIG.

FIG. 6 is an enlarged perspective view showing a thread breakage sensor according to a third embodiment of the present invention.

[Explanation of symbols]

 1 Sewing machine main body 3 Head section 6 Sewing machine needle 7 Thread winding (Upper thread storage section) 8 Upper thread 10 Thread tension 12,21 Thread break sensor 13,22 Holder (Mounting bracket) 16,23,31 Cushion material 17A, 24A Threading hole 17, 24 Vibration plate 18 Piezoelectric body

Claims (2)

[Claims] 1. A sewing machine main body, a head portion provided on the sewing machine main body for reciprocating a sewing needle, and an upper thread stored in a wound state in order to supply the upper thread to the sewing needle of the head section. A thread storage unit, a thread tensioner provided in the head unit, for applying tension to the upper thread supplied from the upper thread storage unit to the sewing machine needle, and the head positioned between the thread tensioner and the upper thread storage unit. Of a sewing machine that is configured to include a thread breakage sensor that detects thread breakage based on sliding of the upper thread by inserting the upper thread that is attached to the upper thread and guided to the thread tension from the upper thread storage section. Thread breakage detection device. 2. The thread breakage sensor is provided with a mounting bracket that is mounted on the head portion, and a needle thread that is provided in the mounting bracket via a cushioning material and slides through a plurality of threading holes. 2. A vibrating diaphragm, and a piezoelectric body which is provided on the vibrating plate and detects a yarn breakage with or without vibration by outputting the vibration of the vibrating plate as an electric signal. A yarn breakage detection device for the sewing machine described.