JPS6117516B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electric sewing machine, and particularly to a safety device for an industrial sewing machine.

Various types of control devices have been proposed for this type of electric sewing machine, particularly for industrial sewing machines.

1 to 3, a control device for an electric sewing machine using an electromagnetic clutch will be explained.

Figure 1 shows the overall configuration of an industrial sewing machine.The sewing machine main body MA is placed on the table TA.
The sewing machine shaft has a pulley PUL ₂ and a position detection mechanism PS.
is installed.

Pulley PUL ₂ table TA through belt VB
This _{pulley PUL 1 is} directly connected to the output shaft of the transmission mechanism TP, which includes a clutch part and a brake part.
It is now driven by MO.

CB is a controller with a control circuit, and a foot pedal
It is controlled by the output signal of the switch FSW operated by the FP and the position detection mechanism PS.

Furthermore, as shown in FIG. 2, the transmission mechanism TP section includes a clutch plate CLB which is movably disposed in the axial direction between a clutch friction plate CLM and a brake friction plate BRM connected to the rotating shaft of the motor MO, The pulley PUL ₁ is directly connected to this clutch plate CLB.

And the clutch plate CLB above is a clutch coil.
By energizing CL, the clutch friction plate CLM
By engaging with the brake friction plate BRM and rotating, and exciting the brake coil BR, the brake friction plate BRM is engaged and stopped.

Further, as shown in FIG. 3, the clutch coil CL is connected to a power source _V1 via a transistor _T1 , and this transistor _T1 is operated by a clutch signal CLS.

Similarly, the brake coil BR is also connected to the power supply _V1 via a transistor _T2 , and this transistor _T2 is operated by the brake signal BRS.

Furthermore, the TR is a transistor in the thread trimming drive coil.
This _transistor T ₃ is operated by the thread trimming signal TRS.

Furthermore, WP is a thread wiper drive coil, KLT is a presser foot lifter drive coil, and each transistor
It is connected to the power supply V ₁ via T ₄ and T ₅ , and these transistors T ₄ and T ₅ each receive a thread removal signal.
It is controlled by WPS and presser foot lifting signal KLTS.

In the above configuration, when the foot pedal FP shown in Fig. 1 is stepped forward, the clutch signal CLS is output by the foot switch FSW, and the clutch coil is activated.
CL is energized via the transistor _T1 , and the clutch plate CLB is pressed against the clutch friction plate CLM, causing the pulley _PUL1 to rotate.

As a result, pulley PUL ₂ is driven via belt VB, and the sewing machine shaft is rotated.

When you release your foot from the foot pedal FP in this state, the foot pedal FP becomes in a neutral state, the position detection mechanism PS detects the lower position of the sewing machine needle, and the detection signal is used to set the clutch signal CLS to zero to set the clutch coil CL. The brake coil BR is deenergized and the brake signal BRS is generated for a short period of time to excite the brake coil BR.

Therefore, the sewing machine shaft is braked, and when the sewing machine needle reaches the lower position, it stops there.

Next, when the foot pedal FP is reversely depressed, the thread trimming signal TRS and clutch signal CLS are generated simultaneously, the thread trimming drive coil TR and the clutch coil CL are energized, and the sewing machine shaft rotates and the thread trimming operation is also performed at the same time. .

When the sewing machine needle reaches the upper position, the position detection mechanism PS generates an upper position signal, and a thread trimming signal is generated.
TRS and clutch signal CLS are turned off at the same time, and brake signal BRS is generated for a short time to control the brake coil.
Energize BR and stop the sewing machine needle at the upper position.

At the same time, the thread removal signal WPS is generated for a short time to excite the thread removal drive coil WP to remove the cut thread, and then the presser foot lifting signal KLTS is issued to push up the presser foot and take out the sewing product freely. make it happen.

Each control signal in such conventional equipment is
It is composed of logic elements such as TTL, and even if electrical noise intrudes for a short period of time, it returns to normal after the noise disappears, and malfunctions are rare.

However, configuring such conventional devices with logic elements such as TTL requires a large number of elements.
In addition, there are cost and size problems such as a large mounting area, and it has been found that these problems can be greatly improved by using a microcomputer with a higher degree of integration.

However, although this microcomputer is capable of performing functions similar to logic circuits through programming, it is susceptible to malfunctions due to very short-term electrical noise from the outside, and this noise intrusion This causes the program to jump from a normal program routine to another routine, and even after the noise disappears, the original normal operation does not return.
Operational problems may occur.

Furthermore, if large fluctuations in the power supply voltage occur, the microcomputer will no longer operate normally.
The contents of outputs, registers, memory, etc. may go awry.

If the power supply voltage drops sufficiently and you reset the computer, there will be no problem, but if the power supply voltage immediately returns to normal due to a temporary fluctuation, the output, register, or Since the program is executed based on the contents of memory, there is a risk that the program will not operate normally and cause an unexpected accident.

The present invention has been made in view of the problems of the conventional devices as described above.In a control device that uses a microcomputer in the control circuit, even if an abnormal signal is output from the computer, the sewing machine malfunctions due to the protection circuit. The purpose of this is to protect the operator from danger and prevent damage to the equipment.

The main feature of the present invention is that the control device for an electric sewing machine has at least a part of it a microcomputer, and the output of the control device controls each mechanism according to a predetermined sequence. When a command signal for operating the mechanism is issued, the operation signal for the thread trimming mechanism is immediately invalidated unless a signal for driving the sewing machine shaft at a predetermined low speed is issued at the same time as this command signal. This is because a protection circuit has been added.

An embodiment of the present invention will be described below with reference to FIG. In the figure, DD and UD are the lower position signal and upper position signal of the position detection mechanism PS, respectively.
TSW and LSW are the reverse and forward signals of the foot switch FSW operated by the foot pedal FP.

Also, CLSM, BRSM, TRSM, WPSM and
KLTSM are output signals from the microcomputer MCPU, which are a clutch signal, a brake signal, a thread trimming signal, a thread sweep signal, and a presser foot lifting signal, respectively.

Each of these signals is output in a predetermined sequence by a program stored in the microcomputer MCPU.

Furthermore, HS is a microcomputer MCPU
Another output of the thread trimming signal TRSM is a constant speed holding signal to keep the rotational speed of the sewing machine shaft at a constant speed while the thread trimming mechanism is operating, and the speed control circuit SCC is connected to the input end of the

Each output terminal of the microcomputer MCPU is connected to each signal terminal for the clutch, brake, thread trimmer, etc. through an AND gate constituting a protection circuit.

In the device of the present invention configured as described above, now,
Clutch signal of microcomputer MCPU
A case will be described in which both CLSM and brake signal BRSM are turned on at the same time, that is, become high level (hereinafter simply referred to as H level).

The clutch signal CLSM is connected to input 1 of the AND gate AND _{1 .}
Input 1 of is at H level, but since brake signal BRSM is connected to its input 2 via inverter _INV1 , input 2 is at low level (hereinafter simply referred to as L level).

Therefore, the output of the AND gate _AND1 , that is, the clutch signal CLS, is held at the L level, and the clutch coil CL is not excited, so that the sewing machine is not driven.

Also this clutch signal CLSM, brake signal
Since BRSM is connected to inputs 1 and 2 of AND gate AND ₉ , the output of this AND gate AND ₉ becomes H level.

The output of this AND gate AND ₉ is also input to the signal terminal INT of the microcomputer MCPU via the OR gate OR ₁ , thereby forcing the brake signal BRSM to the H level for a certain period of time and controlling the other output signals. By programming all the clutch signals to be at L level,
In an abnormal situation where CLSM and brake signal BRSM become H level at the same time, the brake coil BR
only is energized for a certain period of time, and the sewing machine is forcibly stopped.

Therefore, even if the sewing machine is rotating, it will be stopped immediately, and at the same time, the thread trimming, thread sweeping, and presser foot lifting mechanisms will stop all operations, and the alarm ARM will be activated to prevent abnormal conditions. Inform.

Next, when the thread trimming signal TRSM turns on, that is, becomes H level, the sewing machine shaft must rotate at a predetermined constant resistance speed.
This constant speed hold signal HS is sent to the microcomputer.
MCPU is outputting.

And this thread trimming signal TRSM and constant speed hold signal
If HS does not reach the H level at the same time, the sewing machine will be operated at high speed, which will damage the thread trimming device and lead to unsafe operations such as breaking of the sewing machine needle.

So the thread trimming signal TRSM and gate AMD ₃
By connecting the constant speed holding signal HS to input 1 of AND gate AND ₃ , the output of AND gate AND ₃ will be at L level unless both signals go to H level. is held and the thread trimming signal TRS is not output.

Therefore, unsafe operations such as damage to the thread cutting device and breakage of the sewing machine needle as described above do not occur.

Also, this thread trimming signal TRSM is an AND gate.
The constant speed hold signal HS is input to input 1 of AND ₆ .
This AND gate is connected to input 2 of AND gate AND ₆ through INV ₃ .
When the inputs of AND ₆ both go to H level, the microcomputer is connected through its output OR gate OR ₁ .
Feedback is sent to the MCPU, and as mentioned above, the brakes are activated for a certain period of time and the alarm ARM is activated.

Next, the thread removal signal WPSM and the presser foot lifting signal
Normal operation for both KLTSM is for the sewing machine needle to stop at the upper position before outputting.

If the sewing machine rotates during the thread wiper operation, the thread wiper may come into contact with the sewing machine needle and cause an accident such as breaking the sewing machine needle, so such an operation must never be performed.

Therefore, when the thread removing signal WPSM is at the H level and the thread removing operation is to be performed, the clutch signal CLSM must be at the L level.

So thread removal signal WPSM and gate AND ₄
By connecting the clutch signal CLSM to the input 2 of the AND gate AND ₄ via the inverter INV ₂ , the thread removal signal WPSM is
When the clutch signal CLSM is at the H level and the clutch signal CLSM is at the H level, the output of the AND gate _AND4 is at the L level, and the thread removal signal WPS is not output.

In addition, by connecting the thread removal signal WPSM to the input 1 of the AND gate AND ₇ and the clutch signal CLSM to its input ₂ , when both inputs of the AND gate AND ₇ become H level, the AND gate
The output of AND ₇ is fed back to the interrupt signal INT of the microcomputer MCPU via the OR gate OR ₁ , and the brake is operated for a certain period of time to forcibly stop the sewing machine, as described above, and at the same time, the alarm ARM is activated to detect an abnormality. Notify the status.

On the other hand, when the presser foot is raised, the fabric cannot be fed by the feeding device installed in the sewing machine, which not only prevents sewing work but also causes problems such as thread tangling. When raising the sewing machine, the sewing machine must be in a stopped state.

Furthermore, before driving the sewing machine, it is necessary to lower the presser foot to make it ready for sewing.

Therefore, if this presser foot lifting signal KLTSM is connected to input 1 of AND gate AND ₅ , and clutch signal CLSM is connected to its input 2 via inverter INV ₂ , when both signals are at H level, the input of AND gate AND ₅ Since input 1 is at H level and input 2 is at L level, the output of AND gate AND ₅ is at L level, and the presser foot lifting signal KLTS is not output, and the presser foot does not operate.

In addition, the clutch signal CLSM and the presser foot lifting signal KLTSM are connected to inputs 1 and 2 of the AND gate _AND8 , so if both signals become H level at the same time,
The output of this AND gate _AND8 becomes H level, and is fed back to the microcomputer MCPU via the OR gate _OR1 in the same way as described above, and the brake is activated for a certain period of time and at the same time an alarm is activated.
Activate ARM.

The above explanation has been about individual abnormal phenomena, but the same applies even if several of these occur at the same time. In order to immediately stop the sewing machine by applying the brake and cancel other operation commands,
For example, even if an abnormal command signal is issued from the microcomputer, sufficient safety can be ensured.

As described above, in the present invention, when a thread trimming signal is issued from the microcomputer, the thread trimming signal is invalidated unless a signal instructing the sewing machine to run at a low speed is issued at the same time. Since the thread trimming mechanism is prevented from operating, unsafe operations such as the sewing machine needle and the thread trimming device coming into contact with each other or the sewing machine needle breaking and flying off can be prevented.

[Brief explanation of the drawing]

Fig. 1 is a mechanical diagram for explaining the configuration of an electric sewing machine, Fig. 2 is a block diagram of the power transmission mechanism shown in Fig. 1, Fig. 3 is a circuit diagram of the drive section in the conventional example, and Fig. 4 is the invention of the present invention. FIG. 3 is a circuit diagram of a control signal section in one embodiment of the device. MA...sewing machine body, MO...motor, CL...
Clutch coil, BR...brake coil,
MCPU...Microcomputer.

Claims (1)

[Scope of Claims] 1. A clutch mechanism for transmitting the rotational force of the motor to the sewing machine and driving it, a brake mechanism for applying braking force to the sewing machine, and stopping the needle of the sewing machine at a predetermined position. a thread trimming mechanism that automatically cuts the sewing thread after sewing is finished; a thread removal mechanism that removes threads cut by the thread trimming mechanism; and controls for controlling the operations of each of the mechanisms described above. In an electric sewing machine equipped with a device, the control device is configured at least in part by a microcomputer, and when a command signal for operating the thread trimming mechanism is output from the microcomputer, the control device simultaneously performs a command signal to operate the thread cutting mechanism. A safety device for an electric sewing machine, comprising a protection circuit that disables the operation signal of the thread trimming mechanism when a constant speed command signal for driving the sewing machine at a predetermined low speed is not issued.