JP2001225375A - Method and apparatus for controlling molding machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control a plurality of motors by one inverter and to reduce the capacity of the inverter. SOLUTION: The capacities of a main motor 1 and an auxiliary motor 2 are set up so that a necessary motor capacity during a maximum load is larger than the capacity of the main motor 1 in commercial rating operation and smaller than the total capacity of the main motor 1 and the auxiliary motor 2 in commercial rating operation. During a high load, the main motor 1 and the auxiliary motor 2 are operated in commercial rating, and during a low load, the main motor 1 or the auxiliary motor 2 is operated through a common inverter 4. Since the inverter 4 is used only during a low load, its capacity can be lower than a commercial rating motor capacity to reduce the cost of the inverter. By changing over motors in use, a plurality of motors can be controlled by one inverter.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a control apparatus and a control method for a molding machine driven by driving a hydraulic pump by a motor.

[0002]

2. Description of the Related Art An injection molding machine used for molding resin, rubber, or the like uses a hydraulic circuit for generating an extremely high pressure, and is driven by a hydraulic pump driven by a motor. In order to suppress power consumption due to useless driving of the motor and to suppress carbon dioxide generated from the hydraulic device and causing global warming, a power match circuit or the like is used. However, a power match circuit or the like is mainly used for a small injection molding machine. For example, it is difficult to use a large injection molding machine exceeding 500 t due to problems such as noise and responsiveness.

[0003] In recent years, therefore, a control device has been adopted which drives a plurality of motors using an inverter to reduce power consumption. As shown in FIG. 3, the control device includes a main circuit 201 that supplies power from the power supply unit 100 to the main motor 200, an auxiliary circuit 301 that supplies power from the power supply unit 100 to the auxiliary motor 300, and an inverter 40 that supplies power to the auxiliary motor 300.
0, and the auxiliary inverter circuit 3 for supplying power from the power supply unit 100 to the auxiliary motor 300 via another inverter 500.
The switches 203, 303, 204, and 304 are disposed in the main circuit 201, the auxiliary circuit 301, the main inverter circuit 202, and the auxiliary inverter circuit 302, respectively.

At the time of high load such as injection, the main circuit 201 and the auxiliary circuit 301 are turned on, and the main motor 200 is turned on.
Drive both the auxiliary motor 300 and the commercial rated capacity,
At the time of medium load such as pressure holding, the switches 203, 303, 2
By turning on / off the switches 04 and 304, at least one of the main motor 200 and the auxiliary motor 300 is driven via at least one of the inverter 400 and the inverter 500. When there is almost no load, at least one of the main motor 200 and the auxiliary motor 300 is stopped. By controlling in this manner, power consumption can be suppressed, and generation of carbon dioxide can also be suppressed.

[0005]

However, in the above-described conventional control device and control method, two inverters are required, and the capacity of each inverter needs to be a capacity corresponding to the capacity of each motor. For example, if the capacity of the main motor 200 is 45 kW, the inverter 4
00 needs to be 45 kW or more, and if the capacity of the auxiliary motor 300 is 22 kW, the inverter 500
Needs to be 22 kW or more.

However, in the case of injection molding or the like, a high load is applied for a very short time, but when the load is high, an inverter having a high capacity is used in accordance with the capacity of the motor, although the inverter is not used. There must be. In addition, although a high-capacity inverter is used, the inverter is used when the load is low, and there is a problem that there is much waste. The higher the capacity of the inverter, the more expensive it is. Further, since two inverters are used, the conventional control device becomes extremely expensive, and cost reduction is required.

The present invention has been made in view of such circumstances, and has as its object to control a plurality of motors with one inverter and reduce the capacity of the inverter.

[0008]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a control device of a molding machine according to the present invention is characterized in that a main motor and an auxiliary motor of a molding machine having a main motor and an auxiliary motor for driving a hydraulic pump are rotated. In a control device that controls the number of each, a main circuit that supplies power to the main motor from the power supply unit, an auxiliary circuit that supplies power to the auxiliary motor from the power supply unit, a main inverter circuit that supplies power to the main motor from the power supply unit via the inverter, An auxiliary inverter circuit that supplies power to the auxiliary motor from the power supply unit via an inverter, a main switch that turns the main circuit on and off, an auxiliary switch that turns the auxiliary circuit on and off, and a main inverter switch that turns the main inverter circuit on and off And a circuit part comprising an auxiliary inverter switch for turning on and off the auxiliary inverter circuit, and a main switch, an auxiliary switch, a main inverter switch, and an auxiliary input switch. More will control unit for controlling the ON-OFF of Tasuitchi is to control each main motor and the auxiliary motor using a single inverter.

The control method of the molding machine according to the present invention has the following features.
In a control method for controlling a main motor and an auxiliary motor of a molding machine having a main motor and an auxiliary motor for driving a hydraulic pump, a required motor capacity at a maximum load is larger than a capacity at a time when the main motor is operated at a commercial rated operation. Set the capacity of the main motor and the auxiliary motor so that both the main motor and the auxiliary motor are smaller than the total capacity when both the main motor and the auxiliary motor are operated at the commercial rated operation. It is to control the capacity of the main motor or the auxiliary motor to be smaller than the capacity at the time of commercial rated operation by driving the main motor or the auxiliary motor through a common inverter at the time of load.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described by taking an example of controlling an injection molding machine, but the present invention is not limited to control of an injection molding machine. It goes without saying that the present invention can be applied to other molding methods. Further, the present invention can be applied to a case where the number of motors is two or more, and is also applicable to a case where a plurality of three or more motors are controlled using a plurality of inverters.

In injection molding, a mold clamping process, an injection process or a charge process requires an extremely high pressure.
A high load acts on the motor. Therefore, when such a process is performed using the control device and the control method of the present invention, the main circuit and the auxiliary circuit are turned on and the main inverter circuit and the auxiliary inverter circuit are turned on by the control of each switch by the control unit. Set to OFF. As a result, both the main motor and the auxiliary motor are rotated at high speed in commercial rated operation without passing through the inverter, and the hydraulic pump generates the maximum pressure.

The pressure-holding step can be performed at a lower pressure than that of the injection step, and the cooling step can be performed at a pressure low enough to hold the mold in a closed state. In the mold opening process or the ejecting process, the operation may be performed at a lower pressure. Therefore, in these strokes, the load on the motor is smaller than in the injection stroke and the like.

In the present invention, these steps can be performed by operating one of the main motor and the auxiliary motor at the commercial rated speed and stopping the other, or by rotating one motor at a low speed via an inverter. When only one of the main motor and the auxiliary motor is to be operated at the commercial rating, only one of the main circuit and the auxiliary circuit may be turned on. When one motor rotates at a low speed via an inverter, only one of the main inverter circuit and the auxiliary inverter circuit may be turned on, and only one of the main circuit and the auxiliary circuit may be turned on, or both may be turned on.
It can be turned off. Note that the target values of the rotation speeds of the main motor and the auxiliary motor by the above control differ depending on the molding conditions, so they need to be set by trial and error.

When controlling the number of rotations of the motor via the inverter, it does not make sense to control the motor on which a high load acts. Therefore, according to the control device and the control method of the present invention, when a high load is applied, the motor is driven by the commercial rated operation without the intervention of the inverter, so that the inverter is not required and the power consumption can be reduced. In addition, by stopping one of the motors according to the load, or performing one of the operations at the commercial rated operation and the other through the inverter, the power consumption can be reduced and the generation of carbon dioxide can be suppressed.

Further, since the inverter is used only when the load is low, the inverter capacity can be lower than the commercial rated capacity of the motor, so that the cost required for the inverter can be reduced. , The initial capital investment cost can be greatly reduced.

Further, at the time of no load, it is possible to save power by stopping and driving without using an inverter, rather than stopping and driving the motor by using an inverter, and in the present invention, it is possible to do so. Therefore, power consumption can be further reduced.

[0017]

The present invention will be described below in detail with reference to examples.

FIG. 1 is a block diagram of a power supply circuit of the control device according to the present embodiment. This control device controls a main motor 1 and an auxiliary motor 2 for driving a hydraulic pump of a 550 t large-sized injection molding machine. The power supply circuit includes a main circuit 10 for supplying power from the power supply unit 3 to the main motor 1. And an auxiliary circuit 20 for supplying power from the power supply unit 3 to the auxiliary motor. The main circuit 10 includes a main switch 11 for turning the main circuit 10 on and off, and the auxiliary circuit 20 includes an auxiliary switch for turning the auxiliary circuit 20 on and off. 21 are provided.

An inverter 4 is connected in parallel with the main circuit 10 and the auxiliary circuit 20, and before and after the inverter 4,
A first switch 12 and a second switch 13 for turning on and off the connection with the main circuit 10 are provided, and a third switch 22 and a fourth switch 23 for turning on and off the connection with the auxiliary circuit 20 are provided, respectively. Further, a control unit 5 for independently controlling the first switch 12, the second switch 13, the third switch 22, and the fourth switch 23 is provided.

The rated capacity when the main motor 1 is operated at the commercial rated operation is 45 kW, and the rated capacity when the auxiliary motor 2 is operated at the commercial rated operation is 22 kW. The inverter 4 has a low capacity of 22 kW.

A method for controlling a 550 t large injection molding machine using the control device of this embodiment will be described with reference to FIGS. First, a state in which the empty mold is opened after the previous molding is completed will be described. In this state, the main motor 1 is in a stopped state, the third switch 22 and the fourth switch 23 are turned off, the auxiliary switch 21 is turned on,
The auxiliary motor 2 is operated at the commercial rating without passing through the inverter 4.

The first switch 12 and the second switch 1
3 is turned off, the main switch 11 is turned on, and the main motor 1 is also in commercial rated operation.

In this state, first, the mold is closed in the mold closing stroke, and the main motor 1 and the auxiliary motor 2 are each driven at the rated capacity. A mold clamping stroke and an injection stroke requiring pressure are performed.

In the pressure-holding step after the injection step, since the pressure is not so high, the third switch 22 and the fourth switch 23 are turned on and the auxiliary switch 21 is turned off.
As a result, the auxiliary motor 2 has a capacity of 7
Driven at kW. Since the main motor 1 is maintained at the commercial rated operation, the pressure-holding process is performed by the main motor 1 having a capacity of 45 kW and the auxiliary motor 2 having a capacity of 7 kW.

In the charging process after the pressure-holding process, the third switch 22 and the fourth switch 23 are turned off and the auxiliary switch 21 is turned off because it is necessary to increase the pressure again.
When it is turned ON, the auxiliary motor 2 is operated at the commercial rated value again without passing through the inverter 4. As a result, the hydraulic pump generates a maximum hydraulic pressure, and in that state, a charging process requiring a high pressure is performed.

Since the cooling process can be performed at a low pressure, the first switch 12 and the second switch 13 are turned on, and the main switch 11 is turned on.
Is turned off, the main motor 1 is operated at a capacity of 11 kW via the inverter 4, and the auxiliary switch 21 is
It is turned off and the auxiliary motor 2 is stopped. Therefore, the hydraulic pump is driven only by the main motor 1 driven at a capacity of 11 kW, and the mold is closed at a low pressure.

Since a higher pressure is required in the mold opening process after the molded product is cooled than in the cooling process, the first switch 12 and the second switch 13 are turned off, the main switch 11 is turned on, and the auxiliary motor 2 is turned on. Is stopped, the hydraulic pump is driven only by the commercial rated operation of the main motor 1, and the mold is opened. Since the process of ejecting the molded product requires a higher pressure than the process of opening the mold, the auxiliary switch 21 is turned on, and the auxiliary motor 2 is further operated at the commercial rated operation.

After the molded article is ejected, the process returns to the first mold closing stroke and the next molding cycle is performed.

That is, in the control device and the control method of this embodiment, the main motor 1 and the auxiliary motor 2 are alternately controlled by using one inverter 4. The inverter 4 has a low capacity. Therefore, the number of inverters can be reduced as compared with the related art, and a low-capacity inverter can be used, so that the cost required for the inverter can be extremely reduced.

Further, since the main motor 1 and the auxiliary motor 2 can be intermittently stopped and started without the intervention of the inverter 4,
Power consumption can be reduced as compared with the case where the operation is stopped and started via the inverter 4.

[0031]

According to the control device and the control method of the present invention, a plurality of motors can be driven by one low-capacity inverter, and the capital investment cost and power consumption can be greatly reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a power supply circuit of a control device according to an embodiment of the present invention.

FIG. 2 is a time chart illustrating a control method according to an embodiment of the present invention and illustrating a driving mode of a motor in injection molding.

FIG. 3 is a block diagram showing a power supply circuit of a conventional control device.

[Explanation of symbols]

1: Main motor 2: Auxiliary motor 3:
Power supply unit 4: Inverter 5: Control unit 10:
Main circuit 20: Auxiliary circuit

Claims (2)

[Claims] 1. A control device for controlling the rotational speeds of a main motor and an auxiliary motor of a molding machine having a main motor and an auxiliary motor for driving a hydraulic pump, respectively. Circuit, an auxiliary circuit for supplying power to the auxiliary motor from the power supply unit, a main inverter circuit for supplying power to the main motor from the power supply unit via the inverter, and an auxiliary inverter for supplying power to the auxiliary motor from the power supply unit via the inverter A circuit, a main switch for turning on and off the main circuit, and an auxiliary switch for turning on and off the auxiliary circuit;
A circuit portion including a main inverter switch for turning on and off the main inverter circuit and an auxiliary inverter switch for turning on and off the auxiliary inverter circuit; the main switch, the auxiliary switch, the main inverter switch, and the auxiliary inverter switch; A control device for a molding machine, comprising: a control unit for controlling ON / OFF of the main motor and the auxiliary motor using one inverter. 2. A control method for controlling a main motor and an auxiliary motor of a molding machine having a main motor and an auxiliary motor for driving a hydraulic pump, respectively. The capacities of the main motor and the auxiliary motor are set so as to be larger than the capacity at the time of rated operation and smaller than the total capacity of both the main motor and the auxiliary motor at the time of commercial rated operation. The main motor and the auxiliary motor were both operated at the commercial rated speed, and when the load was low, the capacity of the main motor or the auxiliary motor was operated at the commercial rated speed by driving the main motor or the auxiliary motor through a common inverter, respectively. A method for controlling a molding machine, wherein the capacity is controlled to be smaller than the capacity at the time.