CN210368218U

CN210368218U - Broken thread detection device and flat seaming machine

Info

Publication number: CN210368218U
Application number: CN201921112861.3U
Authority: CN
Inventors: 胡程威; 闫池; 杨聪聪; 于恒基
Original assignee: Jack Sewing Machine Co Ltd
Current assignee: Jack Technology Co Ltd
Priority date: 2019-07-16
Filing date: 2019-07-16
Publication date: 2020-04-21
Anticipated expiration: 2029-07-16

Abstract

The utility model provides a broken string detection device and flat seaming machine, including the casing, can install in the swing head of casing, connect the elastic element between swing head and casing, detect the sensor and with detect sensor matched with trigger piece with tilting, have the line hole of crossing that holds the suture and pass in the swing head, and the swing head drives the downward swing by the suture, and elastic element supports at the lower extreme of swing head, detects the sensor and triggers the piece and sets firmly respectively overhead at casing and swing. This application utilizes the line tension of suture to drive swing head wiggle downwards, changes the line tension of suture and turns into the motion of detecting sensor or trigger piece, makes detecting sensor's output signal change to this judges whether the suture has taken place the broken string. The method and the device for detecting the disconnection of the electrode are used for non-contact disconnection detection, and avoid the generation of electric sparks and the knocking noise of the metal contact when the electrode is in contact with or separated from the electrode, so that the method and the device have high disconnection detection accuracy and good reliability.

Description

Broken thread detection device and flat seaming machine

Technical Field

The utility model relates to a make up machinery, especially relate to a broken string detection device and install this broken string detection device's flat seaming machine.

Background

In the process of sewing cloth, the sewing machine generally has the problem of thread breakage, but the sewing of high-grade clothes and the like does not allow the thread breakage. However, under the condition that the sewing machine works at a high speed, operators are difficult to find broken threads in time, and how to detect the broken threads in real time and give an alarm is always an important technical problem in the sewing machinery industry.

At present, thread breakage detection devices are installed in some sewing machines (such as flat seaming machines), and the thread breakage detection devices used in the flat seaming machines are mechanical contact switches similar to mechanical switches; because the sewing speed of the flat seaming machine is high in the sewing process, the switching frequency of the mechanical contact switch is high, and an electric arc invisible to naked eyes can be generated at a contact point; as the time of use elapses, the contact point is oxidized, and the contact resistance becomes large, thereby affecting the service life of the mechanical contact switch. Meanwhile, in order to secure contact reliability of the mechanical contact switch, a spring used in the mechanical contact switch must be pre-stressed with a certain strength when contacting with the opposite electrode, and thus such mechanical contact switches often fail when the bobbin thread tension is small. In addition, the mechanical contact switch is interfered by oil stain on the thread and the contact is poor, so that the mechanical contact switch cannot work normally, and noise is generated in the using process.

SUMMERY OF THE UTILITY MODEL

In view of the above-mentioned shortcomings of the prior art, an object of the present invention is to provide a broken wire detection device, which can effectively detect broken wires and has good reliability.

In order to achieve the above object, the present invention provides a broken string detection device, which includes a housing, a swing head rotatably mounted on the housing, an elastic element connected between the swing head and the housing, a detection sensor, and a trigger cooperating with the detection sensor, wherein the swing head has a thread passing hole for passing a thread, and the swing head is driven by the thread to swing downwards; when the suture drives the swinging head to swing downwards, the elastic element is in an energy storage state.

Furthermore, the elastic element is a spring piece, one end of the spring piece is fixed on the shell, and the other end of the spring piece abuts against the lower end of one end, provided with the wire passing hole, of the swing head.

Further, the detection sensor is a hall sensor, the trigger is a permanent magnet, and the hall sensor and the permanent magnet are respectively fixed to the shell and the swing head.

Further, the detection sensor is a reflection-type photoelectric sensor and is provided with a first transmitting end and a first receiving end, the trigger is a reflector, both the first transmitting end and the first receiving end of the reflection-type photoelectric sensor can be aligned with the reflector, and the reflection-type photoelectric sensor and the reflector are respectively fixed on the shell and the swing head.

Further, the light reflecting piece is made of light reflecting paper or a polished surface.

Further, the detection sensor is fixed on the shell, and the trigger piece is fixed on the swinging head.

Further, the detection sensor is a transmission-type photoelectric sensor, and has a second transmitting end and a second receiving end which are arranged oppositely, the trigger piece is a light through hole formed in the swing head, and the second transmitting end and the second receiving end of the transmission-type photoelectric sensor are respectively arranged on two sides of the light through hole and are fixedly installed on the shell.

Further, a damper body is fixed to the housing on the upper side of the swing head, and the damper body can abut against the swing head.

Furthermore, a ceramic wire sleeve is fixedly installed in the swinging head, and the wire passing hole is formed in the ceramic wire sleeve.

The application also provides a flat seaming machine, has the casing, install as above in the flat seaming machine broken string detection device, the casing is fixed in the casing, the bobbin thread of flat seaming machine wears to establish in the line hole of crossing of swing head, and drives swing head downswing.

As described above, the utility model relates to a broken string detection device and flat seaming machine has following beneficial effect:

this application utilizes the line tension of suture to drive swing head wiggle downwards, and then drives and detects sensor or trigger piece and produce a decurrent displacement together, turns into the motion that detects sensor or trigger piece with the line tension change of suture, makes the output signal who detects the sensor change to this judges whether the suture has taken place the broken string, thereby detects the broken string in real time effectively. Particularly, the method is used for non-contact broken wire detection, and avoids the generation of electric sparks when electrodes are contacted or separated, so that the method has a long service life and high broken wire detection accuracy, has good reliability, and avoids knocking noise of metal contacts.

Drawings

Fig. 1 is a schematic structural diagram of a break line detection apparatus according to a first embodiment of the present application.

Fig. 2 is a rear view of fig. 1.

Fig. 3 is a schematic view of the connection between the detection sensor and the interposer in fig. 1.

Fig. 4 is a schematic structural diagram of a third embodiment of the break line detection apparatus according to the present application.

Fig. 5 and 6 are schematic diagrams illustrating a relationship between the detection sensor and the swing head in fig. 4 at different viewing angles.

Fig. 7 is a schematic structural diagram of a second embodiment of the break line detection apparatus according to the present application.

Fig. 8 is a schematic view showing a relationship between the detection sensor and the swing head in fig. 7.

Fig. 9 is a schematic structural view of the swing head in fig. 7.

Description of the element reference numerals

1 casing

2 oscillating head

21 pin hole

3 elastic element

4 detecting sensor

41 Hall sensor

42 reflection type photoelectric sensor

421 first transmitting terminal

422 first receiving terminal

43 transmission type photoelectric sensor

431 second transmitting terminal

432 second receiving end

5 triggering part

51 permanent magnet

52 reflecting piece

53 light-through hole

6 damping body

7 ceramic wire sleeve

71 wire through hole

8 bottom line

9 wire briquetting

10 adapter plate

11 Pin

Detailed Description

The following description is provided for illustrative purposes, and other advantages and features of the present invention will become apparent to those skilled in the art from the following detailed description.

It should be understood that the drawings of the present application are only used to match the contents disclosed in the specification, so as to be known and read by those skilled in the art, and not to limit the practical limitations of the present invention, so that the present application does not have any technical significance, and any modification of the structure, change of the ratio relationship, or adjustment of the size should still fall within the scope of the present application without affecting the function and the achievable purpose of the present application. Meanwhile, the terms such as "upper", "lower", "left", "right", "middle" and "one" used in the present specification are for convenience of description only, and are not intended to limit the scope of the present invention, and changes or adjustments of the relative relationship thereof are considered as the scope of the present invention without substantial changes in the technical content.

The application provides a flat seaming machine, in the sewing process of the flat seaming machine, a bottom thread 8 of the flat seaming machine reciprocates back and forth, the forward motion of the bottom thread 8 refers to the thread outgoing consumption direction of the bottom thread 8, therefore, in the view shown in fig. 1, 4 or 7, the extending direction of the bottom thread 8 is also the back and forth direction of the bottom thread 8 during the back and forth reciprocating motion.

The flat seaming machine comprises a casing and a broken thread detection device. As shown in fig. 1 to 3, or fig. 4 to 6, or fig. 7 to 9, the disconnection detecting device includes a housing 1, a swing head 2 mounted to the housing 1 to be rotatable up and down, an elastic member 3 connected between the swing head 2 and the housing 1, a detecting sensor 4, and a trigger 5; the swing head 2 is provided with a thread passing hole 71 for a thread to pass through, the swing head 2 is driven by the thread to swing downwards, and the thread passing hole 71 is penetrated back and forth along the extending direction of the thread; the elastic element 3 is supported at the lower end of the swinging head 2, and when the swinging head 2 is driven by the suture to swing downwards, the elastic element 3 is in an energy storage state; the detection sensor 4 and the trigger 5 are respectively fixed on the shell 1 and the oscillating head 2, namely: the detection sensor 4 is fixedly arranged on the shell 1, the trigger piece 5 is fixedly arranged on the swinging head 2, or the detection sensor 4 is fixedly arranged on the swinging head 2, and the trigger piece 5 is fixedly arranged on the shell 1; in the application, the detection sensor 4 is arranged on the shell 1, and the trigger piece 5 is arranged on the swinging head 2; the detection sensor 4 is matched with the trigger 5, and when the trigger 5 displaces, the output signal of the detection sensor 4 can be changed. After the thread breakage detection device is installed in the flat seaming machine, the shell 1 is fixed on the machine shell, and the bottom thread 8 of the flat seaming machine penetrates through the thread passing hole 71 of the swinging head 2 and drives the swinging head 2 to swing downwards.

In the sewing process of the flat seaming machine, the bottom thread 8 reciprocates back and forth in each sewing period to change the tension of the bottom thread 8, the bottom thread 8 acts on the hole wall of the thread passing hole 71, and when the tension of the bottom thread 8 overcomes the elasticity of the elastic element 3, the swinging head 2 is driven to swing downwards; when the tension of the bottom line 8 is smaller than the elastic force of the elastic element 3, the elastic force applied by the elastic element 3 to the swing head 2 drives the swing head 2 to swing upwards; therefore, under the combined action of the tension of the bottom thread 8 and the elastic element 3, the swing head 2 can be driven to swing up and down through the change of the tension of the bottom thread 8 in each sewing period, the swing head 2 drives the trigger piece 5 to swing up and down together, the detection sensor 4 can detect the swing through the matching of the trigger piece 5, the output signal of the detection sensor 4 is changed periodically, and then a periodic signal is output in each sewing period, and the periodic signal is preferably a pulse signal. If the thread is broken, the tension of the lower thread 8 disappears, the swing head 2 does not swing, and the output signal of the detection sensor 4 does not change. Thus, by determining the output signal of the detection sensor 4, it is possible to determine whether or not a wire break has occurred, thereby effectively detecting a wire break in real time.

Further, in the thread breakage detection device related to the present application, the tension change of the bobbin thread 8 in the flat seaming machine is utilized to make the swing head 2 and the trigger piece 5 generate displacement, the thread tension change of the bobbin thread 8 is converted into the movement of the swing head 2 and the trigger piece 5, and the detection sensor 4 is used for detecting whether the swing head 2 and the trigger piece 5 generate displacement, that is, judging the thread tension of the bobbin thread 8, and further judging whether the bobbin thread 8 is broken. The detection mode is non-contact broken wire detection, and electric sparks are prevented from being generated when the electrodes are contacted or separated, so that the detection mode has long service life and high broken wire detection accuracy, the application has good reliability, and meanwhile, knocking noise of metal contacts is avoided. Compared with a contact switch sensor, the contact switch sensor needs to ensure good electrical contact, and when a spring of the contact switch sensor is in contact with an opposite electrode, elastic contact force with certain strength needs to be ensured, so that the contact switch sensor can be failed when the tension of a bottom line 8 is reduced; the elastic element 3 in the present application does not need to prefabricate the elastic force, that is, when the line tension of the bobbin thread 8 does not act on the swing head 2 in the initial state, the elastic force applied by the elastic element 3 to the swing head 2 is zero, so that the swing head 2 can still swing downwards when the line tension of the bobbin thread 8 becomes small, and the thread breakage detecting device in the present application is ensured to be still effective when the line tension of the bobbin thread 8 becomes small, thereby ensuring the reliability and the large measuring range of the thread breakage detecting device.

Further, the types of the detecting sensor 4 and the triggering member 5 cooperating with the detecting sensor 4 may be various, so that the disconnection detecting device has different embodiments based on different types of the detecting sensor 4 and the triggering member 5. The present application provides preferred embodiments of three disconnection detection devices.

The first embodiment of the wire breakage detection device: using Hall detection

As shown in fig. 1 to 3, the detection sensor 4 is a hall sensor 41, the trigger 5 is a permanent magnet 51, the hall sensor 41 is fixedly installed on the housing 1, and the permanent magnet 51 is fixedly installed in the square hole of the swing head 2. The change of the line tension of the bobbin thread 8 acts on the swing head 2 through the hole wall of the thread passing hole 71, the increased line tension causes the swing head 2 to displace downward, so that the permanent magnet 51 installed in the swing head 2 displaces downward, the distribution of the magnetic field generated by the permanent magnet 51 changes, the change of the magnetic field is detected by the hall sensor 41, and the hall sensor 41 outputs a high level. As the thread tension of the lower thread 8 is weakened in one sewing cycle, the elastic force of the elastic member 3 drives the swing head 2 to swing upward, pushing the swing head 2 back upward to the initial position, and the hall sensor 41 outputs a low level. Due to the characteristic of tension change of the bottom thread 8 in the flat seaming machine, the Hall sensor 41 can output one or two pulse signals in each sewing period, and the pulse signals are related to the thread tension change of the bottom thread 8; if the wire is broken, the wire tension of the lower wire 8 is lost, the swing head 2 does not swing, and the hall sensor 41 does not output a pulse signal. Therefore, the controller in the flat seaming machine monitors whether the Hall sensor 41 outputs a pulse signal in each sewing period, and then whether the bottom thread 8 is broken can be judged.

In the first embodiment of the wire breakage detecting device, the change of the wire tension of the bobbin thread 8 is converted into the movement of the permanent magnet 51, and the movement changes the magnetic induction intensity sensed by the fixed hall sensor 41, so that the hall sensor 41 outputs a pulse signal; it judges whether the swinging head 2 swings by judging whether the hall sensor 41 outputs a pulse signal, and further judges whether the bobbin thread 8 is broken. The first embodiment of the disconnection detecting device employs the hall sensor 41, which has the advantage of being resistant to contamination such as cilia and dust, compared to other types of sensors.

Further, as shown in fig. 1 to fig. 3, the first embodiment of the disconnection detecting device further includes a wire pressing block 9 and an adapter plate 10, the adapter plate 10 is fixed on the housing 1, the hall sensor 41 is fixed on the adapter plate 10 and is in communication connection with the adapter plate 10, and the wire pressing block 9 is fixed on the housing 1 and presses the wire led out from the adapter plate 10.

Second embodiment of the wire breakage detection device: by reflective photoelectric detection

As shown in fig. 4 to 6, the detecting sensor 4 is a reflective photoelectric sensor 42 having a first emitting end 421 and a first receiving end 422, and the triggering element 5 is a reflecting element 52; the reflection type photoelectric sensor 42 is fixedly installed on the housing 1, and the reflection member 52 is fixedly provided on the swing head 2. Preferably, the reflective member 52 may be reflective paper adhered to the oscillating head 2, or a polished surface processed on the oscillating head 2. The line tension change of the bottom line 8 acts on the swinging head 2 through the hole wall of the line passing hole 71, the increased line tension makes the swinging head 2 displace downwards, so that the reflector 52 fixedly arranged on the swinging head 2 also moves downwards, the reflection of the light emitted by the first emitting end 421 of the reflective photoelectric sensor 42 to the first receiving end 422 is reduced, and the reflective photoelectric sensor 42 outputs a high level after the set threshold value is exceeded. As the thread tension of the bobbin thread 8 is decreased in one sewing cycle, the elastic force of the elastic element 3 drives the swing head 2 to swing upward to push the swing head 2 back to the initial position, and the light emitted from the first emitting end 421 of the reflective photo-sensor 42 is reflected to the first receiving end 422 as before, so that the reflective photo-sensor 42 outputs a low level. In the normal continuous sewing process of the flat seaming machine, the reflective photoelectric sensor 42 can output one or two pulse signals in each sewing period due to the tension change characteristic of the bottom thread 8; if the wire is broken, the wire tension of the lower wire 8 disappears, the swing head 2 does not swing, and the reflection type photoelectric sensor 42 does not output a pulse signal. Therefore, the controller in the flat seaming machine monitors whether the reflective photoelectric sensor 42 outputs a pulse signal in each sewing period, and then whether the bottom thread 8 is broken can be judged.

In the second embodiment of the thread breakage detecting device, the change of the thread tension of the bobbin thread 8 is converted into the change of the reflected light intensity, and the reflective photoelectric sensor 42 outputs a pulse signal according to the change of the reflected light intensity, so as to determine whether the swing head 2 swings, thereby determining whether the bobbin thread 8 is broken.

Third embodiment of the wire breakage detection device: using transmission-type photoelectric detection

As shown in fig. 7 to 9, the detecting sensor 4 is a transmissive photosensor 43, and has a second emitting end 431 and a second receiving end 432 that are oppositely disposed, the second emitting end 431 is a light emitting tube, the second receiving end 432 is a photodiode or a phototransistor, the triggering element 5 is a light passing hole 53 that is formed on the swinging head 2, an extending direction of the light passing hole 53 is consistent with an extending direction of the wire passing hole 71, and both the light passing hole and the light passing hole are penetrated in the front and back direction, and the second emitting end 431 and the second receiving end 432 of the transmissive photosensor 43 are respectively disposed on the front and back sides of the light passing hole 53 and both the light passing hole and the light passing hole are fixedly mounted on the housing 1. The line tension change of the bottom line 8 acts on the swing head 2 through the hole wall of the line passing hole 71, the increased line tension makes the swing head 2 displace downward, so that the light passing hole 53 on the swing head 2 also moves downward, the light path between the second emitting end 431 and the second receiving end 432 of the transmission type photoelectric sensor 43 is cut off, the light emitted by the light emitting tube cannot irradiate on the photodiode or the phototriode, and the transmission type photoelectric sensor 43 outputs high level. As the thread tension of the lower thread 8 is decreased in one sewing cycle, the elastic force of the elastic member 3 drives the swing head 2 to swing upward to push the swing head 2 back to the initial position, the light emitted from the light emitting tube is irradiated on the photodiode or the phototransistor through the light passing hole 53 of the swing head 2, and the transmissive photosensor 43 outputs a low level. In the normal continuous sewing process of the flat seaming machine, the transmission type photoelectric sensor 43 outputs one or two pulse signals in each sewing period, and the pulse signals are related to the line tension change of the bottom line 8; if the thread is broken, the thread tension of the lower thread 8 disappears, the swing head 2 does not swing, and the transmissive photosensor 43 does not output a pulse signal. Therefore, the controller in the flat seaming machine monitors whether the transmission type photoelectric sensor 43 outputs pulse signals in each sewing period, and whether the bottom thread 8 is broken can be judged.

In the third embodiment of the thread breakage detecting device, the change of the thread tension of the bobbin thread 8 is converted into the change of the transmitted light intensity, and the transmission type photoelectric sensor 43 outputs a pulse signal according to the change of the transmitted light intensity, so as to judge whether the swing head 2 swings, and thus judge whether the bobbin thread 8 is broken.

Further, in the above three embodiments of the disconnection detecting device, the wire passing hole 71 is disposed at the outer end of the swinging head 2, and the inner end of the swinging head 2 is rotatably mounted on the housing 1 through the pin 11, so that the inner end of the swinging head 2 is provided with the pin hole 21 matched with the pin 11, as shown in fig. 6 or fig. 9; the pin 11 forms a swing shaft of the swing head 2, the pin 11 is fixed on the shell 1, and the swing head 2 in the broken line detection device is in a cantilever type structure. Preferably, the elastic element 3 is a spring plate, one end of the spring plate is fixed to the housing 1, and the other end of the spring plate abuts against the lower end of the swing head 2 provided with the outer end of the wire passing hole 71. As shown in fig. 1, or fig. 4 and 6, or fig. 7 and 9, a ceramic wire sleeve 7 is fixedly installed in the circular hole at the outer end of the swing head 2, and a wire passing hole 71 is formed in the ceramic wire sleeve 7, so that the wear resistance of the wire passing hole 71 is improved, and the wire breakage detecting device is durable; the tension variation of the bobbin thread 8 acts on the oscillating head 2 through the ceramic thread bush 7, causing the oscillating head 2 to oscillate downwards about the pin 11. As shown in fig. 1, 4, or 7, the damping body 6 is fixed to the housing 1 above the swing head 2, the damping body 6 can abut against the swing head 2, the damping body 6 can limit the swing width of the upward swing when the swing head 2 is returned, the reliability is improved, and the noise generated by the collision between the swing head 2 and the housing 1 can be prevented, so that the damping body 6 can perform both the functions of limiting and preventing the generation of noise. Preferably, the material of the damping body 6 may be rubber or foam, and the housing 1 is an integrally injection-molded part.

Further, in the above three embodiments of the yarn breakage detecting device, the outer end of the oscillating head 2 is an open structure, that is, the outer end of the oscillating head 2 does not have a housing structure, and therefore, it is not easy to hang the contamination such as dust and cilia, or once the contamination such as dust and cilia is hung, the contamination is very easy to clean, so that the accumulation of the contamination such as dust and cilia can be reduced.

Furthermore, the flat seaming machine provided with the thread breakage detection device is also provided with an alarm module, and the alarm module and a detection sensor 4 in the thread breakage detection device are connected with a controller of the flat seaming machine; the controller judges whether or not the thread breakage occurs according to whether or not the pulse signal is output from the detection sensor 4 for each sewing cycle: if the detection sensor 4 outputs a pulse signal, judging that the line is not broken; if the detection sensor 4 does not output pulse signals, the disconnection is judged, and at the moment, the controller sends instructions to the alarm module to trigger the alarm module to alarm.

To sum up, the utility model discloses various shortcomings in the prior art have effectively been overcome and high industry value has.

The above embodiments are merely illustrative of the principles and effects of the present invention, and are not to be construed as limiting the invention. Modifications and variations can be made to the above-described embodiments by those skilled in the art without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which may be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.

Claims

1. A broken wire detection device is characterized in that: the device comprises a shell (1), a swinging head (2) which is arranged on the shell (1) in a vertically rotating manner, an elastic element (3) connected between the swinging head (2) and the shell (1), a detection sensor (4) and a trigger piece (5) matched with the detection sensor (4), wherein a thread passing hole (71) for a thread to pass through is formed in the swinging head (2), the swinging head (2) is driven by the thread to swing downwards, the elastic element (3) is supported at the lower end of the swinging head (2), and the detection sensor (4) and the trigger piece (5) are fixedly arranged on the shell (1) and the swinging head (2) respectively; when the suture line drives the swing head (2) to swing downwards, the elastic element (3) is in an energy storage state.

2. The disconnection detection apparatus according to claim 1, wherein: the elastic element (3) is a spring piece, one end of the spring piece is fixed on the shell (1), and the other end of the spring piece abuts against the lower end of one end, provided with the wire passing hole (71), of the swing head (2).

3. The disconnection detection apparatus according to claim 1, wherein: the detection sensor (4) is a Hall sensor (41), the trigger piece (5) is a permanent magnet (51), and the Hall sensor (41) and the permanent magnet (51) are respectively fixed on the shell (1) and the swing head (2).

4. The disconnection detection apparatus according to claim 1, wherein: the detection sensor (4) is a reflection type photoelectric sensor (42) and is provided with a first emitting end (421) and a first receiving end (422), the trigger piece (5) is a reflecting piece (52), both the first emitting end (421) and the first receiving end (422) of the reflection type photoelectric sensor (42) can be aligned to the reflecting piece (52), and the reflection type photoelectric sensor (42) and the reflecting piece (52) are respectively fixed on the shell (1) and the swing head (2).

5. The disconnection detection apparatus according to claim 4, wherein: the reflective member (52) is made of reflective paper or a polished surface.

6. The disconnection detecting device according to claim 3 or 4, wherein: the detection sensor (4) is fixed on the shell (1), and the trigger piece (5) is fixed on the swing head (2).

7. The disconnection detection apparatus according to claim 1, wherein: the detection sensor (4) is a transmission-type photoelectric sensor (43), and is provided with a second emitting end (431) and a second receiving end (432) which are oppositely arranged, the trigger piece (5) is a light through hole (53) formed in the swing head (2), and the second emitting end (431) and the second receiving end (432) of the transmission-type photoelectric sensor (43) are respectively arranged on two sides of the light through hole (53) and are fixedly arranged on the shell (1).

8. The disconnection detection apparatus according to claim 1, wherein: the damping body (6) located on the upper side of the swing head (2) is fixed on the shell (1), and the damping body (6) can be abutted to the swing head (2).

9. The disconnection detection apparatus according to claim 1, wherein: the swing head (2) is fixedly provided with a ceramic wire sleeve (7), and the wire passing hole (71) is formed in the ceramic wire sleeve (7).

10. A flat seaming machine has a machine shell, and is characterized in that: the flat seaming machine is provided with the broken thread detection device of any one of claims 1 to 9, the shell (1) is fixed on a machine shell, and a bottom thread (8) of the flat seaming machine penetrates through a thread passing hole (71) of the swinging head (2) and drives the swinging head (2) to swing downwards.