JPH0889680A - Lock stitch sewing machine - Google Patents

Abstract

PURPOSE: To provide a lock stitch sewing machine capable of detecting a bobbin thread break, and automatically stopping the operation of a lock stitching mechanism by stopping the operation thereof, upon the detection of a stoppage time continuing over the preset time via a feed stop detection means. CONSTITUTION: The feed of a needle thread is stopped and the rotating motion of a rotating guide 23 is stopped, when a bobbin thread is not fed to a rotating hook, thereby fixing the contact position of the resilient operation piece 24a of a micro-switch 24 with the guide 23. As a result, one of a normally close contact 24b and a normally open contact 24c is turned on, and the other is turned off, thereby interrupting power feed to an off-delay timer T2 connected, for example, to the contact 24c in 'off' state. When the preset elapse time is exceeded, the timer T2 comes to have a normally close contact tT2 reset to 'off' state, and a feed detection relay R is released from an energized condition. As a result, power feed to off-delay timers T1 and T2 is interrupted. At the same time, an emergency stop signal is outputted from a stoppage control circuit 3 to a motor drive circuit 31.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lockstitch sewing machine,
Particularly, the present invention relates to a lockstitch sewing machine capable of stopping the lockstitch when the lower thread is not supplied.

[0002]

2. Description of the Related Art In a conventional lock stitch sewing machine, the needle thread is adjusted to a predetermined tension by a thread tension regulator and supplied to a vertically moving lock stitch needle of the lock stitch mechanism, whereby the lock stitch mechanism shown in FIG. As shown in, while feeding the sewing materials 1 and 2, the lock stitch needle 3
The upper thread 4 passed through is engaged with the lower thread 6 fed from the bobbin 5 on the lower side of the sewn materials 1 and 2 for sewing.

[0003]

However, in the above-mentioned conventional lock stitch sewing machine, when the lock stitch needle 3 is moved up and down, the upper thread 4 and the lower thread 6 are engaged with each other to perform the lock stitch. However, the bobbin thread 6 fed from the bobbin 5 may be cut off,
When the bobbin thread 6 wound around the bobbin 5 is used up, even if the bobbin thread 6 is not supplied to the lower side of the lock stitch needle 3, a detecting means for detecting this bobbin thread break state. Since the needle thread is not provided, there is an unsolved problem that the sewing operation cannot be performed because the lock stitching operation is repeated while the upper thread is passed even when the lower thread is broken. Especially when sewing an airbag, which is a part of important safety parts that protects occupants in the event of a vehicle accident, there should be absolutely no stitch skipping or bobbin thread breakage. It is desired to stop the lockstitch operation.

Therefore, the present invention has been made by paying attention to the unsolved problem of the above-mentioned conventional example, and a lockstitch sewing machine capable of automatically stopping the operation of the lockstitch mechanism by detecting a bobbin thread breakage. Is intended to provide.

[0005]

In order to achieve the above object, a lockstitch sewing machine according to a first aspect of the present invention supplies an upper thread to a vertically stitched lockstitch needle of a lockstitch mechanism via a thread tensioner. hand,
In a lock stitch sewing machine that performs lock stitch by engaging with the lower thread, a rotation member that rotates in a guide path of the upper thread according to the conveyance of the upper thread, and a rotation detection unit that detects a rotation state of the rotary member. Is provided with a needle thread feed detecting means including
Feed stop detection means for detecting that the upper thread feed stop state has continued for a set time or longer based on the needle thread feed detection value of the needle thread feed detection means, and the feed stop time for the feed stop detection means for the set time or more And an operation stopping means for stopping the operation of the lock stitching mechanism when it is detected.

In the lockstitch sewing machine according to a second aspect of the present invention, the needle thread feed detecting means engages with the needle thread formed between a pair of thread tension regulators arranged at a predetermined interval in the needle thread guide path. Rotating member, an engaging concave portion formed on the outer peripheral surface of the rotating member at a predetermined interval, and an engaging element engaging with the engaging concave portion, and the normally closed contact and the normally open contact that interlock with each other. And the feed stop detection means is composed of a pair of off-delay timers to which power is individually supplied via a normally closed contact and a normally open contact of the switch.

[0007]

In the lockstitch sewing machine according to the present invention, the needle thread feed detecting means detects the needle thread feed state, and based on the detected value, the feed stop detecting means keeps the needle thread feed stopped state for a set time or longer. When the continuation is detected, the operation stopping means determines that the feeding is stopped due to the bobbin thread breakage and stops the operation of the lock stitching mechanism.

In the lockstitch sewing machine according to claim 2,
By rotating the rotating member in conjunction with the feed of the upper thread, detecting this rotating state with a switch, and individually supplying power to the pair of off-delay timers via the normally closed contact and normally open contact of this switch. , When the normally closed contact and the normally open contact of the switch are alternately turned on and off repeatedly due to the rotation of the rotating member, the contact of the off-delay timer continues to be on, and the bobbin thread feed stops due to bobbin thread breakage. Then, in response to this, the rotation of the rotating member is stopped, and either the normally closed contact or the normally open contact of the switch continues to be in the off state,
When the set time of the off-delay timer is exceeded, the contact turns off and the supply of power to the lockstitch mechanism is stopped.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a schematic configuration diagram of an embodiment of the present invention. A lockstitch sewing machine 10 includes a bed 11 and a bracket arm 12.

The bracket arm 12 has a pair of thread tensioners 14 and 15 for applying a predetermined tension to the needle thread 13 disposed on the upper side thereof, and a thread guide 16 disposed on the left side thereof.
, A thread tension adjuster 17 arranged on the lower end side thereof, a lock stitch balance 18 arranged on the upper side thereof, an electric motor (not shown) arranged on the lower end side thereof, a rotary shaft and a needle. A lock stitch needle 19 that is connected through a rod crank or the like and is vertically moved is provided.

The bed 11 is provided with a cloth feed mechanism 20 at a position opposed to the lock stitch needle 19, and a rotary hook for processing the lower thread is built in below the cloth feed mechanism 20, which is not shown. The feed mechanism 20, the rotary hook, the lock stitch needle 19, the lock stitch balance 18 and the like constitute a lock stitch mechanism 21. here,
The cloth feed mechanism 20 has a cloth retainer 22 disposed on the upper side thereof and movable up and down.

Then, the thread tension 1 of the bracket arm 12
A rotation guide 23, which constitutes an upper thread feed detecting means for detecting the feeding state of the upper thread 13, is rotatably provided between the four and fifteen. As shown in FIG. 2, the rotation guide 23 has a thread guide groove 23b formed at the tip end side of the cylindrical surface of the columnar body 23a, and a predetermined distance in the circumferential direction at the rear end side thereof with an interval of 180 °. A pair of engaging recesses 23 having a width
c and 23d are formed.

On the other hand, the engaging recess 23c of the rotation guide 23,
Micro switch 24 having elastic actuator 24a engaged with engaging recesses 23c and 23d on the left side opposite to 23d.
Is provided. The micro switch 24 is, for example, a normally-closed contact that is turned on when the elastic actuator 24a is engaged with the outer peripheral surface of the rotation guide 23 and is turned off when engaged with the engagement recesses 23c and 23d. 24b and, on the contrary, a normally open contact 24c that is in an off state when engaged with the outer peripheral surface of the rotation guide 23 and is in an on state when engaged with the engaging recesses 23c and 23d.

An emergency stop push button switch 25 is arranged on the tip side of the bracket arm 12. And
A lock stitch balance 18, a lock stitch needle 19, a cloth feed mechanism 20, and a drive circuit 31 of a drive motor 30 for rotationally driving the rotary hook are provided. The drive circuit 31 includes a foot pedal switch 32 as shown in FIG. Drive motor 3 by stepping on
Although 0 is rotationally driven, the rotational drive of the drive motor 30 is emergency stopped by a switch signal from the stop control circuit 33 connected to the stop connectors 31a and 31b.

The stop control circuit 33 includes a stop connector 31.
lines 33a and 33b respectively connected to a and 31b, an emergency stop switch 25 connected between these lines 33a and 33b, and a relay of a feed stop detection circuit 34, which will be described later, connected in parallel with the emergency stop switch 25. Normally closed contact t _R3
It consists of and.

The feed stop detection circuit 34 is, for example, 100V.
Power supply lines 35a, 35b to which commercial AC power is input
And a series circuit 36 of a normally closed contact 24b of the microswitch 24 connected between the power supply lines 35a and 35b and an off-delay timer T1 capable of arbitrarily changing a set time, and connected in parallel with the series circuit 36. The series circuit 37 of the normally open contact 24c of the microswitch 24 and the off-delay timer T2 capable of arbitrarily changing the set time, the switch 35 double-laid with the foot pedal switch 32, and the off-delay. The normally closed contacts t _T1 and t _{T2 of the} timers T1 and T2 and the series circuit 38 of the feed stop detection relay R are connected.

[0017] Here, the feed stop detection relay R has three switching contact of the self-holding contacts t _R1, normally open contact t _R2 and the normally closed contact t _R3, self-holding contacts t _R1 is connected in parallel with the switch 35 The normally open contact t _R2 is inserted between the series circuits 36 and 38 of the power supply line 35a, and the normally closed contact t _R3 is connected between the lines 33a and 33b of the stop control circuit 33 described above.

Next, the operation of the above embodiment will be described. First, the upper thread 13 wound on a bobbin (not shown) is unwound, and the thread tension adjuster 14, the rotation guide 23, the thread tension adjuster 15, the thread guide 16, the thread tension adjuster 17, and the lock stitch needle 18 are used to feed the lock stitch needle 19 And a lower thread is supplied to a rotary hook (not shown), and an airbag as a sewing material is inserted and fixed between the cloth feed mechanism 20 and the cloth retainer 22.

In this state, when the foot pedal is depressed to turn on the foot pedal switch 32, the electric motor 30 is rotationally driven by the motor drive circuit 31, which causes the lock stitch balance 18, the lock stitch needle 19, and the cloth feed mechanism. Two
0, the lockstitch mechanism 21 composed of a rotary hook is operated,
While air-feeding the air bag, sew it with a lock stitch.

At the same time, the switch 35 of the feed detection circuit 34 is turned on, whereby the feed detection relay R
Becomes a biased state, and the self-holding contact t _R1 is closed to form a self-holding circuit. Further, the normally-open contact t _R2 is closed, so that the normally-closed contact 2 of the microswitch 24 is closed.
Off delay timer T via 4b and normally open contact 24c
1 and T2 are energized.

At this time, when the upper thread 13 and the lower thread are normally engaged by the lock stitch mechanism 21 to perform sewing, the upper thread 13 is moved in accordance with the vertical movement of the lock stitch needle 19. Is sent, the rotation guide 23 rotates continuously or intermittently.

In response to this, the elastic actuator 24a of the microswitch 24 is engaged with the outer peripheral surface of the rotation guide 23 and the engaging recess 23.
As a result, the normally closed contact 24c and the normally open contact 24d are turned on, for example, every 10 seconds.
Repeat off.

Therefore, the off-delay timers T1 and T
2 and the elapsed time is measured each time the energization is cut off, but if the energization is started before the set elapsed time elapses, the elapsed time is reset and these normally closed contacts t _{Since T1} and t _T2 continue to be in the ON state, the feed detection relay R continues to be in the energized state.

As described above, when the feed detection relay R continues to be in the energized state, the normally closed contact t _R3 thereof remains in the off state, so that the stop control circuit 33 outputs a switch signal to the motor drive circuit 31. Motor drive circuit 31
Continues to rotate the drive motor 32 and the sewing state is maintained.

In this normal sewing state, when the lower thread is cut or the lower thread wound around the bobbin is used up and the lower thread is not supplied to the rotary hook, the lock stitch needle 19 is lowered. However, since the stitching is not performed, the feeding of the upper thread 13 is stopped. Therefore, the rotation of the rotation guide 23 is stopped, and accordingly, the elastic actuator 2 of the micro switch 24 is stopped.
Since the contact position of 4a with respect to the rotation guide 23 is fixed, the normally closed contact 24b and the normally open contact 24c thereof are fixed.
One of the two, for example, the normally-closed contact 24b is turned on and the other normally-open contact 24c is turned off, so that the power supply to the off-delay timer T2 connected to the normally-open contact 24c in the off state is stopped. It

However, the off-delay timer T2 maintains the normally-closed contact t _T2 in the ON state until the preset elapsed time is exceeded even if the energization is stopped, but when the elapsed time is exceeded, the normally-closed contact t _T2 is closed. t _T2 returns to the off state.

As a result, the energizing path to the feed detection relay R is opened, so that the feed detection relay R is in the non-energized state, and the self-holding contact t _R1 is turned off and the normally open contact t.
_R2 to off state, the normally closed contact t _R3 is respectively returned to the ON state, whereby both power supply to the OFF-delay timer T1 and T2 are cut off, switch signal representative of the emergency stop from the stop control circuit 33 motor It is output to the drive circuit 31, and the motor drive circuit 31 outputs the drive motor 30.
Stop the rotation drive of. Therefore, the sewing operation of the airbag by the lock stitch mechanism 21 is stopped.

Similarly, when the upper thread 13 is entangled during the sewing operation of the airbag, the emergency stop push button switch 25 is pressed to output a switch signal from the stop control circuit 33 in the same manner as above. The output to the motor drive circuit 31 stops the drive motor 30 and the sewing operation of the airbag by the lock stitch mechanism 21 is stopped.

The off-delay timers T1 and T2 are also provided.
The operator can arbitrarily set the elapsed time by rotating and adjusting the setting dial of the controller, and the optimum elapsed time is set in consideration of the feeding state of the upper thread 13 at the time of normal sewing.

In the above embodiment, the feed detecting means is composed of the rotation guide 23 and the micro switch 24. However, the present invention is not limited to this, and the rotation guide 23 may be used instead of the micro switch 24. It is also possible to attach a rotary encoder to and detect the feeding state of the needle thread 13 based on the rotation detection output.

Further, in the above embodiment, the case where the feed detecting circuit 34 is constituted by the sequence circuit using the off-delay timers T1 and T2 and the feed detecting relay R has been described, but the present invention is not limited to this. By applying the programmable controller and performing the program processing, it is possible to obtain the same operational effects as those of the above embodiment.

[0032]

As described above, according to the lockstitch sewing machine of the first aspect, the upper thread is supplied to the vertically-movable lockstitch needle of the lockstitch mechanism via the thread tensioner, and the lower thread is fed. In the lockstitch sewing machine that performs lockstitching, a rotating member that rotates in accordance with the conveyance of the needle thread and a rotation detecting unit that detects the rotating state of the rotating member are provided in the lock stitch sewing machine that performs the lock stitch. And a feed stop detecting means for detecting that the upper thread feed detection value is the upper thread feed detection value, and detects that the upper thread feed stopped state has continued for a set time or more. Since the feed stop detecting means is provided with an operation stopping means for stopping the operation of the lock stitching mechanism when it is detected that the feed stop time is longer than the set time, the feed stop detecting means feeds the upper thread. It is possible to detect the stop condition with certainty. Since this stitch mechanism is stopped by deactivation means it, the effect is obtained that the continuation of the sewing work at the feed out condition of the lower thread can be reliably prevented.

According to the lockstitch sewing machine of the second aspect, the needle thread feed detecting means is arranged on the needle thread formed between a pair of thread tensioners arranged at a predetermined interval in the needle thread guide path. A normally-closed contact and a normally-closed contact that interlock with each other, which include a rotating member to be engaged, an engaging concave portion formed on the outer peripheral surface of the rotating member at a predetermined interval, and an engaging element to engage with the engaging concave portion. Since the feed stop detection means is composed of a pair of off-delay timers to which power is individually supplied through the normally closed contact and the normally open contact of the switch, When the upper thread feed is stopped by the switch of the upper thread feed detecting means, one of the contacts is surely turned off so that the upper thread feed state can be reliably detected, and the off-delay timer is activated based on this. The needle thread feed is stopped. Effect that can be reliably detected.

[Brief description of drawings]

FIG. 1 is a perspective view showing the overall configuration of an embodiment of a lockstitch sewing machine according to the present invention.

FIG. 2 is an enlarged perspective view showing a needle thread feed detection mechanism of a lock stitch sewing machine according to the present invention.

FIG. 3 is a sequence circuit diagram showing an example of a control circuit of the lockstitch sewing machine according to the present invention.

FIG. 4 is an explanatory view showing a sewing state of a conventional example.

[Explanation of symbols]

 10 Lockstitch sewing machine 11 Bed 12 Bracket arm 13 Top thread 14 Thread tension device 15 Thread tension device 19 Lock stitch needle 21 Lock stitch mechanism 23 Rotation guide 23a Cylindrical body 23b Thread guide groove 23c Engagement recess 23d Engagement recess 24 Micro switch 24a Elastic actuator 24b Normally closed contact 24c Normally open contact 30 Drive motor 31 Motor drive circuit 33 Stop control circuit 34 Feed detection circuit R Feed detection relay T1 Off-delay timer T2 Off-delay timer

Claims (2)

[Claims] 1. A lockstitch sewing machine that performs lockstitch by supplying a lock thread through a thread tension regulator to a lockstitch needle that is moved up and down in a lockstitch mechanism and engaging the lock with a lower thread. The upper thread feed detecting means having a rotating member that rotates according to the conveyance of the upper thread and a rotation detecting means that detects the rotating state of the upper thread is disposed in the guide path of the upper thread feeding detecting means. A feed stop detection means for detecting that the stopped state of the upper thread feed has continued for a set time or more based on the needle thread feed detection value, and when the feed stop detection means detects that the feed stop time is the set time or more A lockstitch sewing machine, further comprising: an operation stopping means for stopping the operation of the lockstitch mechanism. 2. The upper thread feed detecting means includes a rotating member that engages an upper thread formed between a pair of thread tension regulators arranged at a predetermined interval in an upper thread guide path, and an outer periphery of the rotating member. The feed recess is formed on the surface at a predetermined interval, and the switch has an engaging element that engages with the engagement recess and has a normally-closed contact and a normally-open contact that interlock with each other. 2. The lockstitch sewing machine according to claim 1, wherein the stop detection means is composed of a pair of off-delay timers to which power is individually supplied via a normally closed contact and a normally open contact of the switch.