JPS644896B2 - - Google Patents

Description

Detailed Description of the Invention [Industrial Application Field] The present invention is directed to an injection molding machine, in particular, to a molding machine using electrically regenerated energy of an AC motor that drives each mechanism of a mold clamping section and a material injection section of an injection molding machine. This invention relates to an energy-saving injection molding machine that uses energy to heat materials.

[Prior Art] Conventionally, in injection molding machines that turn materials such as plastic into desired molded products, hydraulic drive sources have been mainly used as the drive source for driving each mechanism in the injection section that injects into the mold. It was hot.

Recently, the pressure inside molds for injection molding plastics and other materials has been controlled with high precision to eliminate non-uniformity of molded products, and also to eliminate oil smoke atmosphere to produce molded products without oil adhesion. Therefore, there is a tendency for electric servomechanisms to be used as a drive source for the purpose of further reducing maintenance of the drive unit.

The typical operation modes of injection molding machines are as follows:
It is done in stages.

Mold closing → Mold clamping → Injection → Holding pressure → Cooling (plasticization) → Mold loosening → Mold opening → Ejection Each of these eight operation modes has a different operating time, and the control content also depends on position, torque, and speed. This control is carried out. In the above operation process,
An AC motor (synchronous or induction motor) used as a drive source in an electric servomechanism is braked to stop rotation at a predetermined time, and performs a so-called regenerative operation that converts rotational energy into electrical energy. This regeneration operation is performed, for example, at the time of mold clamping, just before the end of injection, just before the end of mold opening, and at the time of ejection. In addition, the time required for one cycle of the 8-stage operation mode is about 15 to 30 seconds, and the AC motor used in the electric servo mechanism is required to operate with high frequency of start and stop operations. is also performed frequently.

[Problems to be Solved by the Invention] In the electric servo drive that repeatedly performs start and stop operations as described above, the electric energy generated during the regenerative operation of the AC motor used as the drive source is passed through the regenerative braking resistor, There is a method of quickly bringing the machine to a halt by consuming it as regenerative energy, but this method has the disadvantage of increasing power loss and reducing the operating efficiency of the injection molding machine. In addition, there is a method to improve operational efficiency by returning the electrical energy to the power supply as regenerative energy through the power supply line, but since the regenerative current contains high frequency components, it is not necessary to connect it in parallel to the power supply line. The drawback was that it had a negative effect on other electrical equipment.

Therefore, it has been a problem to effectively use the regenerated energy in order to improve the operating efficiency of the injection molding machine.

To solve this problem, the present invention provides an energy-saving injection molding machine that uses regenerated energy from an AC motor as material heating energy for the injection molding machine.

[Means for Solving the Problems] The configuration of the present invention for solving the above problems will be explained below using FIG. 1 corresponding to an embodiment. In the present invention, an AC motor 33 is used as a drive source, a heating cylinder 20 is provided, a molding material in the heating cylinder is heated and melted by a heater 19, an injection molding mechanism is driven by the AC motor 33, and the injection molding mechanism is driven by the AC motor 33. In an injection molding machine that injects and molds a melted molding material into a mold space 14, regenerative energy generated during regenerative operation of the AC motor 33 is stored and the regenerative energy is used as heating power for the heater 19. It is equipped with a power storage device 4 that supplies electricity.

[Operation of the Invention] According to the above-described means, the regenerative energy generated during the regenerative operation of the AC motor 33 used to drive the injection molding mechanism is stored in the power storage device 4, and the output power from the power storage device is transferred to the heater 19. Since the regenerated energy is used as material heating energy, the operating efficiency of the injection molding machine is improved.

[Example] Hereinafter, an example of the present invention will be described based on the drawings. In Fig. 1, 1 is the main part of the injection molding machine;
2 is an AC power supply; 3 is a power section of an electric servo mechanism that drives the main section 1; and 4 is a power storage device for storing power from the power section.

The main part 1 of the injection molding machine can be roughly divided into a mold clamping part 11.
The mold clamping part 11 consists of a female mold 12 fixed to the mechanism and a movable male mold 1.
It consists of 3. In the mold clamping part 11, the mold 12
By pressing the mold 13 (mold closing--mold clamping operation), a molten plastic material or the like is injected into the mold space 14 created between the two molds through the injection hole 15 to produce a molded product. and cooling of plastic materials,
After curing, the pressure on the mold 13 is released and the mold 13 is moved back by a predetermined distance (mold loosening - mold opening operation), the molded product is taken out from the mold 12, and then the mold is closed again as described above.
The mold clamping operation begins and the same operation is repeated.
The mold-closing and mold-clamping operations and mold-releasing and mold-opening operations described above are performed by an AC motor for driving the mold clamping section of an electric servo mechanism.

The injection section 16 includes a material input hopper 17, a material supply screw 18, a heating cylinder 20 equipped with a heater 19 consisting of heating elements 19a to 19c, a screw tip space 21 for storing the melted material, and a screw tip space 21 for storing the melted material. Injection hole (or nozzle) 2
Ranked from 2nd class onwards. In the injection section 16, the hopper 1
A small lump of plastic material or the like put into the space 7 is sent toward the space 21 by rotating the screw 18 by an AC motor for driving the injection part of an electric servo mechanism. Then, during the feeding process, it is heated by the heater 19 of the heating cylinder 20,
The plastic material is dissolved from solid to liquid and stored in the space 21. Note that the heating element 19a described above
The heating elements 19b and 19c are energized to keep the temperature of the heating cylinder 19 constant, and the heating elements 19b and 19c heat the heating cylinder 19 by receiving regenerative energy, which will be described later, from the power section, respectively, via the power storage device.

At the moment when a predetermined amount of plastic material is stored in the screw tip space 21 and the mold clamping operation is completed, the screw 18 is moved by a predetermined distance in the direction of the space 21 using the injection unit driving electric motor (injection operation ), the melted material in the space 21 is filled into the mold space 14 of the mold clamping part 11 through the injection hole 22.

The power section 3 of the electric servo mechanism includes a rectifier 31 that full-wave rectifies the output voltage of the three-phase AC power supply 2 and outputs a DC voltage E, and a rectifier 31 that outputs a DC voltage E by full-wave rectification of the output voltage of the three-phase AC power supply 2. An inverter circuit 3 that converts into a three-phase AC voltage and outputs it.
2. An AC motor 33 that is driven by the output of the inverter circuit to drive the injection part 16, a capacitor 34 connected in parallel to the output end of the rectifier 31, and a connection between the positive voltage output side of the rectifier 31 and the positive voltage output terminal 36. It consists of a transistor 35 connected between them, a negative voltage output terminal 37, and the like.

In this power section 3, the DC voltage E from the rectifier 31 is converted into a three-phase AC voltage having a variable frequency by an inverter circuit 32, and an AC motor 33 is driven by this three-phase AC voltage. When this AC motor is brought from an operating state to a stopped state, rotational energy of the motor and a load connected to the motor is converted into electrical energy. This electrical energy is stored in the capacitor 34, and the DC voltage E becomes high. This DC voltage E is boosted to the inverter circuit 3.
If the voltage exceeds the withstand voltage of, for example, a transistor forming part 2, an accident may occur in which the transistor is damaged. Therefore, in order to suppress the increase in the DC voltage E to a predetermined value, the transistor 35 is changed from an open state to a closed state by a control means (not shown), and the electric energy is outputted from the output terminals 36 and 37 as regenerative energy. The DC voltage E is kept below a predetermined voltage value.

The power storage device 4 includes diodes 41 and 44, a chain 42, a capacitor 43, and a capacitor 43 connected as shown in the figure.
It consists of input terminals P ₁ and N ₁ and output terminals P ₂ and N ₂ . This power storage device 4 has input terminals P ₁ ,
When a voltage is applied to _N1 from the power section 3 by the closing operation of the transistor 35, the diode 41
The current value flowing through the chain yoke 42 is suppressed, and regenerative energy is stored in the capacitor 43. The diode 44 bypasses the voltage generated in the choke 42 when the current flowing through the choke 42 is interrupted, thereby preventing the generation of abnormal voltage. capacitor 4
The regenerative energy stored in 3 is output terminal P ₂ ,
By energizing the heating element 19b of the injection section 16 through _N2 , the energy is converted into heating energy for melting the plastic material. The heating elements 19b and 19c of the injection section 16 are shown as two, assuming that one AC motor to be braked is used for driving the mold clamping section 11 and one for driving the injection section 16, respectively. Furthermore, the power section 3 of the electric servo mechanism is connected to the injection section 1.
This figure shows what is used to drive the mold clamping part 1.
Although not shown in the figure, a device similar to No. 1 is used to supply the regenerated energy to the heating element 19c via the power storage device.

As explained above, according to this embodiment, when an AC motor of an electric servo mechanism is used to drive the injection section 16 and mold clamping section 11 of an injection molding machine, the regenerative energy generated by the regenerative operation of the motor is Since the heating energy is used to heat and melt the plastic material for injection molding, power loss can be reduced and the operating efficiency of the injection molding machine can be improved.

Next, a modification of the power storage device 4 used in the above embodiment is shown in FIG. 2. In the figure, a power storage device 4b of this modification has a circuit that is almost the same as the power storage device 4 of FIG _.
Equipped with _N3 .

In the device shown in FIG. 2, the AC voltage e is transferred to the isolation transformer 5
By converting the regenerative energy into a DC voltage in the rectifier circuit 52 and applying it to the input terminals P ₃ and N ₃ through the input terminal 1, a certain value of heating energy can be generated even if regenerative energy is not applied to the input terminals P ₁ and N ₁ . can be applied as a bias.

In the embodiment shown in FIG. 1, one set of inverter circuit 32 and AC motor 33 are provided on the output side of the rectifier 31, but if the rectifier 31 is shared and multiple sets of inverter circuits and AC motors are installed together, ,
The regenerative energy from each AC motor may be converted into heating energy via one power storage device 4.

[Effects of the Invention] As explained above, the injection molding machine of the present invention has the following effects:
The regenerative energy generated during the regenerative operation of the AC motor used to drive the injection molding mechanism that performs the mold clamping operation and the injection operation is stored in the power storage device, and the regenerative energy is used as heating energy to melt the molding material. It is possible to reduce power loss and improve the operating efficiency of the injection molding machine without adversely affecting other electrical devices connected in parallel to the same power source.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing an embodiment of the injection molding machine of the present invention, and FIG. 2 is a circuit diagram showing a modification of the power storage device used in the embodiment of FIG. 1... Main parts of the injection molding machine, 11... Mold clamping part,
14... Mold space, 16... Injection part, 18... Screw, 19... Heater, 19a to 19c...
Heating element, 20... Heating tube, 3... Power section of electric servo mechanism, 33... AC motor, 4, 4b...
Power storage device.

Claims (1)

[Claims] 1. An AC motor is used as a drive source, and a heating cylinder is provided, the molding material in the heating cylinder is heated and melted by the heater, the injection molding mechanism is driven by the AC motor, and the melted molding material is put into a mold. An injection molding machine that performs injection molding by injecting into the fuel cell, characterized in that the injection molding machine is equipped with a power storage device that stores regenerative energy generated during regenerative operation of the AC motor and supplies the regenerative energy to the heater as heating power. Molding machine.