JPS6217953B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to a press machine equipped with a flywheel and a clutch that can be opened and closed between the flywheel and a crankshaft. This invention relates to an on/off operation control device for a motor of a press machine for the purpose of reducing power consumption.

(Prior Art) As a motor for rotating a flywheel of a press machine, an induction motor is mainly used, and a DC motor or the like is also used. In addition, the capacity of the electric motor is selected to have a rated horsepower output that is sufficient to recover even if the rotation of the flywheel decreases due to the workload of the press machine. Press machine is α before bottom dead center
A part of the stored energy of the flywheel is consumed by performing press work in the working angle range from 30° to the bottom dead center, and by the next cycle, the reduction in rotation due to energy consumption is restored and the consumed energy is recovered. are doing. However, once the electric motor of a press machine is started, it is continuously driven regardless of the size of the work load or the working situation, and power is continuously supplied to the electric motor.

(Problems to be Solved by the Invention) In press machines, as described above, energy consumption due to the work load and energy storage due to the electric motor are repeated. However, in reality, the ratio of energy consumption time due to work load to the total operating time is extremely short (near the bottom dead center of the slide).
The electric motor is simply used to maintain the inertial rotation of the flywheel. After the flywheel reaches its rated rotation, the flywheel uses a large amount of inertial rotational energy, so the load on the motor to replenish the consumed energy is small and the current used is small, reducing the efficiency and power factor of the motor. ing. However, electric motors are driven continuously and constantly consume power, resulting in an enormous total power consumption, which is not economical in these days when energy conservation is an issue. In addition, even if you turn on the electric motor and rotate the flywheel to start work, if it takes a lot of time to set up the mold position etc., it will take a long time to turn on the clutch for press work. During this period, the electric motor continues to rotate. In such a case of idle operation, the power consumption of the electric motor becomes enormous and is not economical.

(Means for Solving the Problems) In view of the above-mentioned conventional problems, it is an object of the present invention to provide an operation control device that reduces the power consumption of the electric motor of a press machine.

The first feature of the present invention is that the rotational speed of the electric motor is constantly monitored, and when the rotational speed reaches a specified value, the motor power is automatically turned off, and when the rotational speed falls below the specified rotational speed, it is turned on. It can be turned on and off repeatedly during the slide cycle.

The second feature is that after the flywheel reaches its rated rotation, the flywheel has a large amount of inertial rotational energy, so it can easily bear the energy consumption due to the work load. Set the working angle range using a rotary cam switch, etc., turn off the motor power only during the time of the set angle, and turn it on at other angles.
It can be turned on and off repeatedly for each cycle.

A third feature is that after the motor is started, if the clutch is not turned on and the press operation is not started within a predetermined period of time, the motor is turned off.

The present invention is characterized in that it aims at reducing the power consumption of the electric motor by integrating the above-mentioned methods.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 shows an example in which an AC three-phase induction motor is used as the flywheel drive motor of a press machine, and FIG. 2 shows an example in which a DC motor is used.

In Fig. 1, IM indicates an induction motor connected to a 3-phase AC power supply (AC200V), a no-use breaker NFB is inserted in each power supply line, and each of the 2-phase power supply lines is
Switching circuits SCR1 and SCR2, which are two thyristors connected in antiparallel, and overcurrent detection heat elements TH-1 and TH-2 are connected in series. TG is a speed detection generator that outputs a low-voltage three-phase AC voltage according to the rotational speed of the electric motor IM, and the AC voltage is converted into a DC voltage by a diode bridge circuit 3D. VR1 is diode bridge circuit 3D and motor speed control circuit
It is a variable resistor for speed feedback inserted between ASR, and VR2 is a variable resistor for setting the specified rotational speed of the electric motor IM. Further, RS is a rotary cam switch (not shown) attached to the press crankshaft, and is used to control the on/off of the electric motor IM.When this switch RS is closed, an interface circuit IF1 configured by a photocoupler is operates to output an on signal for the motor IM, and when switch RS is opened, an off signal for the motor IM is output, and the on and off signals are input to the speed control circuit ASR. In addition, STR is a switch for starting the electric motor, and by turning it on, interface IF2 operates, outputting a starting signal for the electric motor and speed control circuit.
Entered into ASR. PH is speed control circuit
The firing angle of switching circuits SCR1 and SCR2 is set by a phase shifter provided at the output stage of ASR. A pulse amplifier PA is provided at the output stage of this phase shifter PH, and the switching circuit is controlled by this output.
The configuration is such that gate control of SCR1 and SCR2 is performed.

In addition, when the DC motor shown in Figure 2 is adopted, the rotation control of the DC motor DCM is controlled by the induction motor IM.
This is almost the same as in the case of . switching circuit
The SCR has a pure bridge configuration using six thyristors, and after converting to DC, a DC motor (DCM) is used.
is applied to In addition, DC motor DCM is generally
Since 100% control (not flowing more than the rated current) is used in most cases, unlike the case of induction motors, a current control circuit ACR is installed between the speed control circuit ASR and the phase shifter PH, and current transformation is applied to the two-phase power supply line. A controller CT is provided to detect the current in the case of a DC motor and input it to the current control circuit ACR via the rectifier 3DA. In addition, VR3
is a variable resistor for current feedback setting. Also, Tr
is a transformer that lowers the voltage to AC200V when the AC power source is 400V, and a rectifier 2D is installed on the secondary side of the transformer Tr, which supplies current to the field coil FC for speed control of the motor DCM. ing. The other configurations are the same as in FIG. 1.

Next, the operation of the present invention will be explained. The case of the circuit configuration shown in FIG. 1 will be explained, but the on/off control in the case of FIG. 2 is also the same, and the explanation will be omitted. 1st
We will explain the operation when the rotation speed of the motor is monitored and the motor power is turned off when the rotation speed reaches the specified speed. First, the specified rotational speed of the electric motor is set by variable resistor VR2, and
The variable resistor VR1 is set according to the value, and a specified motor rotation speed is set. In this case, the variable resistor
VR2 is set to a value equal to the AC input voltage at full firing.

The speed control circuit ASR is started by turning on the start switch STR, and the switching circuit SCR is activated by its output pulse signal.
1. SCR2 is gate-on controlled and motor IM is driven. When the motor IM reaches the specified rotation speed, that is, when the feedback voltage from the speed detection generator TG matches the voltage set by the variable resistor VR2, the gate pulse signal is set to zero and the switching circuits SCR1 and SCR2 are activated. off and turn off the motor power.

Next, when the motor IM drops below the specified rotation speed, turn on the power. During the cycle operation of the slide, switching circuits SCR1 and SCR2 are repeatedly turned on and off. In this way, in the case of the induction motor IM, the purpose can be achieved simply by comparing and monitoring the constant rotation speed, and once the variable resistor VR1
Once you set VR2, there is no need to make any adjustments after that.

Therefore, for example, when the operating energy consumption at the bottom dead center of the slide is small, the gate-on control time of the switching circuit is short, and the power consumption of the electric motor is small. In other words, the inertia of the flywheel can be used effectively. If energy consumption is large, the flywheel takes time to return to normal rotation, so the electric motor power is turned on before the slide reaches top dead center. When the specified rotation speed is reached, the switching circuit is turned off in the same manner as described above, and by repeating on and off operations, the motor can be driven in accordance with the workload, reducing power consumption of the motor. It is something that will be done.

Next, an explanation will be given of the second characteristic point, which is the case where the crank angle of the working angle range of the press machine is set and the electric motor power is turned off only during the time period corresponding to the set angle. A rotary cam switch installed on the press crankshaft adjusts the crank angle of the press work range.
RS (not shown). When the flywheel reaches its rated rotation and press work begins, the electric motor power is turned off during the above-mentioned set angle time.
It is controlled to be on except for the set angle band. That is, the press operation angle range is passed by turning off the electric motor power and consuming the inertial rotational energy of the flywheel, and the consumed energy is recovered in the remaining angle range. Although on/off control is repeated for each press cycle, the inertial rotational energy of the flywheel can be effectively used to reduce the power consumption of the electric motor.

Next, Figure 3 shows the third feature of the present invention, which is that if the clutch is not engaged within a predetermined time after the motor is started, the motor power is cut off to prevent dry running. It is something.

In FIG. 3, STR is a switch circuit inserted into the motor starting signal line, and corresponds to the starting switch in FIGS. 1 and 2. A motor automatic stop timer circuit TA is provided in parallel with this switch circuit STR, a normally closed contact TA-1 of the timer circuit TA is connected in series with the switch circuit STR, and a clutch of the press machine is connected in series with the timer circuit TA. The normally open contact STR-1 of the switch circuit STR is connected to the press clutch circuit PC, which keeps the power circuit closed when the power supply circuit is not turned on.
Furthermore, a start push button switch Sa and a stop push button switch Sb are connected in series with the normally closed contact TA-1, and are connected to a power supply line. In addition, TH-1
is a contact that opens when an overcurrent is detected, and when a DC motor is used, it jumps as shown by the broken line.

Next, the effect will be explained. According to the circuit shown in Figure 3,
The switch circuit STR is activated by closing the start push button switch Sa, and the switch STR
-1 is closed. As a result, the power supply line of the electric motor is turned on, and the electric motor (not shown) is started. At the same time, the timer circuit TA starts,
If the clutch is not engaged within the set time of the timer circuit TA, the normally closed contact TA-1 of the timer circuit TA will open after the set time has elapsed, and the motor power will be turned off.
The electric motor is stopped. The clutch circuit PC is provided to reset the timer circuit TA, and when the clutch circuit PC is turned on, the timer circuit TA is reset and the normally closed contacts that were open are reset.
TA-1 will be closed as before. Therefore, if the clutch is engaged within the set time of the timer circuit TA, the power to the motor remains on without being turned off, and the motor continues to drive. As described above, after starting the electric motor, if a predetermined period of time elapses without any press work being performed for setup work such as mold positioning, the electric motor power is automatically turned off, thereby reducing unnecessary power consumption of the electric motor.

In the above-mentioned embodiment, the operation of the electric motor was explained separately with regard to reducing power consumption, but these can be installed in parallel in one press machine having a flywheel. Further, although the description has been given using a press machine as an example, the present invention can be widely applied to devices having a flywheel such as a cutting machine.

(Effects of the Invention) As explained above, according to the present invention, the motor power source is turned on and off depending on the work load state, work situation, etc.
Since it is turned off, there is no waste in the use of the electric motor, and power consumption can be significantly reduced. Particularly, by effectively utilizing the inertial rotational energy of the flywheel, the effect of achieving energy savings in the electric motor is significant.

[Brief explanation of the drawing]

The attached drawings are for explaining one embodiment of the present invention, and Fig. 1 is a motor operation control circuit diagram when an induction motor is used as the drive source of the press machine, and Fig. 2 is a motor operation control circuit diagram when a DC motor is used as the drive source of the press machine. FIG. 3 is a partially omitted circuit diagram of the motor operation control circuit in which the motor power is turned off by measuring the time from when the motor is started until the clutch is engaged. NFB is a no-use breaker, SCR1, SCR
2 is a switch circuit, TH-1 and TH-2 are overcurrent detectors, IM is an induction motor, TG is a speed detector,
VR1 to VR3 are variable resistors, RS is a rotary cam switch, IF1 and IF2 are interface circuits,
STR is a start switch, ASR is a speed control circuit, PH is a phase shifter, PA is a pulse amplifier, 2
D, 3D, 3DA are rectifier circuits, SCR is a thyristor start switch circuit, FC is a field coil, CT is a current transformer, Tr is a transformer, Sa, Sb are push button switches, TA
is a timer circuit, and PC is a press clutch circuit.

Claims (1)

[Claims] 1. In a press machine equipped with a flywheel and a clutch that can be opened and closed between the flywheel and a crankshaft, a starting circuit for an electric motor for driving the rotation of the flywheel, and a speed setting circuit for setting a specified rotation speed of the electric motor are provided. , a speed detection circuit that detects the actual rotation speed of the motor; and a power supply control that turns off the power to the motor when the detected speed exceeds a set speed, and turns on the power to the motor when the detected speed falls below the set speed. an angle setting circuit for setting the working angle range of the press machine; and an angle setting circuit for setting the working angle range of the press machine; and when the flywheel reaches a specified rotation speed, the electric motor is turned off during the set angle time period, and the electric motor is turned off outside of the above time period. a power control circuit that turns on the power of the motor, a timer circuit that measures the time after the motor starts and sends an alarm when the set time elapses, and a timer circuit that turns off the power of the motor if the clutch is not engaged within the set time after the motor starts. 1. An on/off operation control device for a motor of a press machine, comprising a power supply control circuit for controlling the power supply.