JP4652224B2 - Servo power supply device for electric injection molding machine and control method for servo power supply device for electric injection molding machine - Google Patents

Description

  The present invention relates to a servo power supply device for an injection molding machine driven by a servo motor and a control method for the servo power supply device for an electric injection molding machine.

  The drive shaft of the electric injection molding machine driven by the servo motor is the injection shaft that injects molten resin into the mold, the screw rotation shaft for kneading and weighing the resin, the mold opening and closing shaft that opens and closes the mold, molding It consists of a projecting shaft that projects the product from the mold and is usually equipped with a 4-axis servo system (servo amplifier, servo motor).

  When designing a servo system, a relatively small machine can be designed more efficiently with a 200V servo system. However, as the size of electric injection molding machines increases, Since the capacity increases, the 400V system configuration is advantageous due to problems such as wire size.

  However, the injection shaft and screw rotation shaft that require a large output, such as an injection molding machine, must have a large capacity, but the mold opening / closing shaft and the protruding shaft have a large capacity even in a machine that does not have such a large capacity. It is necessary to design a servo system according to the thing, and it is necessary to make all the drive shafts 400V system.

  On the other hand, for small-capacity drive shafts, if you want to take advantage of the 200V system by design, or if you need to mix the 200V system due to parts management problems, use a transformer as shown in FIG. It was necessary to prepare a 200V system.

  Hereinafter, a description will be given with reference to FIG. The power supply 5 has a three-phase 400V, and a 400V DC voltage is supplied between P1 and N1 by a 400V class converter 10A. A servo system of 400V class is connected between P1 and N1, and as an example, an injection servo amplifier 1 and a servo motor 11, a screw rotating shaft servo amplifier 2 and a servo motor 12 are connected.

  On the other hand, the 200V system voltage obtained by the transformer 6 is supplied between P2 and N2 by the 200V class converter 10B. A servo system of 200V class is connected between P2 and N2, and as an example, a mold opening / closing servo amplifier 3 and a servo motor 13, and a protruding servo amplifier 4 and a servo motor 14 are connected. In addition, the following patent document 1 is known as related technology.

Japanese Patent Laid-Open No. 2001-232672

  As shown in FIG. 2, when a system in which a 400V system and a 200V system are mixed is to be configured, in the case of 400V power supply, a transformer 6 for newly generating a 200V system is required, and further a DC voltage is generated. In addition to the 400V converters 1 and 2, a 200V converters 3 and 4 are also required.

  As described above, if a system with both 400V and 200V systems is to be configured, it is essential to install a transformer to divide the power supply system, and a converter circuit is required for each power supply system. It becomes inefficient.

  The present invention has been made to solve the above-described problems in the prior art, and is an electric injection molding machine that is simple in configuration, low in cost, and can realize a highly efficient servo system. It is an object of the present invention to provide a servo power supply device and a control method for the servo power supply device of an electric injection molding machine.

  In order to solve the above-described problem, the servo power supply apparatus of the electric injection molding machine of the present invention forms an intermediate potential point of DC voltage by forming a smoothing capacitor in series between DC voltage lines of the servo power supply, A servo amplifier for driving a servo motor between the DC voltage lines, and between the high voltage side of the DC voltage line and the intermediate potential point, or between the low voltage side of the DC voltage line and the intermediate potential point; A servo amplifier for driving the servo motor is provided between the two.

  In the servo power supply device for the electric injection molding machine of the present invention, the servo power supply device includes a balancer circuit capable of changing the voltage at the intermediate potential point to an arbitrary voltage between the DC voltage lines and the intermediate potential point. The balancer circuit is constituted by a switching element and a coil.

  In the servo power supply apparatus for the electric injection molding machine according to the present invention, the balancer circuit detects the potential at the intermediate potential point and controls the switching element so that the voltage at the intermediate potential point becomes a predetermined voltage level. It is characterized by that.

  Further, in the servo power supply device of the electric injection molding machine according to the present invention, the balancer circuit changes the voltage of the intermediate potential point between the high voltage side of the DC voltage line and the intermediate potential point, or the The supply voltage to the servo amplifier installed between the low voltage side of the DC voltage line and the intermediate potential point is changed.

  The present invention also provides a servo amplifier for driving a servo motor between the DC voltage lines by forming a smoothing capacitor in series between the DC voltage lines of the servo power supply to form an intermediate potential point of the DC voltage. And a servo amplifier for driving a servo motor between the high voltage side of the DC voltage line and the intermediate potential point, or between the low voltage side of the DC voltage line and the intermediate potential point. In a control method for a servo power supply device of an injection molding machine, the balancer circuit includes a balancer circuit capable of changing the voltage of the intermediate potential point to an arbitrary voltage between the DC voltage lines and an intermediate potential point. By changing the voltage of the intermediate potential point, between the high voltage side of the DC voltage line and the intermediate potential point, or the low voltage side of the DC voltage line Serial and wherein varying the supply voltage to the installed servo amplifier between the intermediate potential point.

  In the control method of the servo power supply device for the electric injection molding machine of the present invention, the DC voltage line voltage is generated by a converter having a switching element, and the converter makes the DC voltage line voltage constant. It is characterized by controlling as follows.

  In the embodiment of the present invention, a PWM converter that generates a constant DC voltage from a 400V system power supply line is provided, and an intermediate potential of the capacitor is provided by connecting a capacitor in series to the DC voltage output (DC voltage line). Furthermore, by providing a small capacity step-up / down chopper circuit that freely controls the voltage of the intermediate potential, a 200V servo system is arranged between the intermediate potential point and the DC voltage output of the PWM converter as shown in FIG. Thus, it is possible to eliminate the transformer for dividing the power supply system and the converter circuit for the 200V system.

  A PWM converter that generates a constant DC voltage has a function of controlling the DC voltage to be constant, and the DC voltage is controlled to be constant with respect to fluctuations in supply voltage and load changes. A step-up / down chopper composed of a switching element (transistor, diode) and control coil is connected to the connection point of the capacitor connected in series between the DC voltage outputs, and the charge voltage of each capacitor connected in series can be freely adjusted. Can be controlled. Therefore, a 200V servo system is placed between the intermediate potential point and the DC voltage line, and even if the intermediate potential point fluctuates due to load supply, the chopper circuit is operated so as to control it, thereby securing a stable intermediate potential. Furthermore, since the stabilization of the DC voltage is ensured by the PWM converter, the 200V servo system can be arranged using the intermediate potential point and the DC voltage line.

  According to the present invention, since there is an intermediate potential point of DC voltage obtained by configuring a smoothing capacitor in series between the DC voltage lines of the servo power supply, one servo motor with a different voltage class is provided. Even when mixed in an injection molding machine, it can be configured in one power supply system, and there is an effect that it is not necessary to prepare two types of power supply systems having different voltage classes. Furthermore, by controlling the balancer circuit and varying the voltage at the intermediate potential point, it is possible to perform PWM control by changing the supply voltage to the servo amplifier arranged between the intermediate potential and the DC voltage line, The loss of the servo amplifier can be reduced by lowering the voltage, or the servo motor output can be increased by raising the voltage, and a highly efficient servo system can be realized.

Embodiments of the present invention will be described below.
FIG. 1 is a configuration diagram of a servo power supply device of an electric injection molding machine showing an embodiment of the present invention. Hereinafter, a description will be given based on FIG.

  A power supply 5 for supplying power to the servo power supply device has a three-phase 400 V and is connected to the PWM converter 10 through a coil L1. The PWM converter 10 controls the current flowing through the coil L <b> 1 in a sine wave shape, and controls so as to output a preset DC voltage between the lines P and N in a constant manner.

  Capacitors C1 and C2 are connected in series between the DC voltage output terminals P and N, and a connection point C of the capacitor is provided as an intermediate potential point of the DC voltage.

  A portion surrounded by a broken line is a balancer circuit 7. The balancer circuit 7 includes power transistors Tr1 and Tr2, flywheel diodes D1 and D2, a smoothing coil L2, and a chopper controller 8 that controls the operation of the power transistor. The chopper controller 8 detects the voltage of the intermediate potential point C. When the potential of C is higher than the predetermined intermediate voltage, the chopper controller 8 turns on the Tr2, and when lower than the intermediate potential, the chopper controller 8 turns on the Tr1. By controlling the power transistor so as to become, the potential of the intermediate potential point C is controlled to be kept at an arbitrary value.

  Normally, the potential at the intermediate potential point C is controlled to a half potential between P and N, but it is also operated as a balancer that changes the balance of the charge voltages of C1 and C2 as necessary.

  For a servo power supply having a DC voltage system (P, N, C) obtained by such a configuration, a 4-axis servo amplifier and motor for driving an injection molding machine are arranged as shown in FIG.

  Servo amplifiers (inverters) 1 ', 2' and servo motors 11, 12 having a voltage class of 400V class are arranged between P and N, which are 400V class DC voltages. Servo amplifiers (inverters) 3 'and 4' and servo motors 13 and 14 having a voltage class of 200V are arranged between P-C or C-N, which are 200V class DC voltage, respectively. .

It is a circuit diagram which shows embodiment of this invention. It is a circuit diagram which shows the prior art.

Explanation of symbols

  1 'to 4' servo amplifier (inverter), 5 power supply, 7 balancer circuit, 8 chopper controller, 10 PWM converter, 11-14 servo motor.

Claims (6)

By forming a smoothing capacitor in series between the DC voltage lines of the servo power supply, an intermediate potential point of the DC voltage is formed, and a servo amplifier for driving a servo motor is provided between the DC voltage lines, and the DC voltage Servo power supply of an electric injection molding machine comprising a servo amplifier for driving a servo motor between the high voltage side of the line and the intermediate potential point, or between the low voltage side of the DC voltage line and the intermediate potential point apparatus. In the servo power supply device of the electric injection molding machine according to claim 1,
A balancer circuit capable of changing the voltage at the intermediate potential point to an arbitrary voltage between the DC voltage lines and the intermediate potential point is provided, and the balancer circuit is configured by a switching element and a coil. Servo power supply for electric injection molding machine. In the servo power supply device of the electric injection molding machine according to claim 2,
The servo power supply apparatus for an electric injection molding machine, wherein the balancer circuit detects a potential at the intermediate potential point and controls a switching element so that a voltage at the intermediate potential point becomes a predetermined voltage level. In the servo power supply device of the electric injection molding machine according to claim 2 or claim 3,
When the balancer circuit changes the voltage of the intermediate potential point, it is between the high voltage side of the DC voltage line and the intermediate potential point, or between the low voltage side of the DC voltage line and the intermediate potential point. A servo power supply device for an electric injection molding machine, characterized in that a supply voltage to a servo amplifier installed in the motor is changed. A smoothing capacitor is formed in series between the DC voltage lines of the servo power supply to form an intermediate potential point of the DC voltage, and a servo amplifier for driving a servo motor is provided between the DC voltage lines, and the DC voltage Servo power supply of an electric injection molding machine comprising a servo amplifier for driving a servo motor between the high voltage side of the line and the intermediate potential point, or between the low voltage side of the DC voltage line and the intermediate potential point In the device control method,
A balancer circuit capable of changing the voltage at the intermediate potential point to an arbitrary voltage between the DC voltage lines and the intermediate potential point;
When the balancer circuit changes the voltage of the intermediate potential point, it is between the high voltage side of the DC voltage line and the intermediate potential point, or between the low voltage side of the DC voltage line and the intermediate potential point. A method for controlling a servo power supply device of an electric injection molding machine, wherein a supply voltage to a servo amplifier installed in the motor is changed. 6. The method of controlling a servo power supply apparatus for an electric injection molding machine according to claim 5 , wherein the voltage between the DC voltage lines is generated by a converter having a switching element, and the converter converts the voltage between the DC voltage lines. A control method for a servo power supply device of an electric injection molding machine, wherein control is performed so as to be constant.

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