JPH0347172B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field to which the Invention Pertains] The present invention relates to an injection molding machine driven by an electric motor, and in particular, a rotary drive shaft used for mold opening/closing operation, injection operation, or screw rotation operation of an injection molding machine is directly connected to an electric motor. This invention relates to a structure in which the rotor of an electric motor is integrally attached.

[Prior art and its drawbacks]

The mold opening/closing operation or injection operation in conventional motor-driven injection molding machines converts the rotary motion of the electric motor into linear motion or approximate linear motion using ball screws and link mechanisms, and power transmission mechanisms such as gear trains, chains, and sprockets. is driven by. The same goes for the screw rotation drive, in which power is transmitted from the rotation of the electric motor to the screw drive shaft via a transmission mechanism such as a gear train or a chain sprocket.

Therefore, not only the mechanical structure becomes large, but also
This has the disadvantage that the rotational inertia of the drive system becomes large, reducing the responsiveness of not only starting and stopping operations but also acceleration and deceleration control. Furthermore, when using a clutch to connect and release the driving force, a brake to maintain the injection force and mold clamping force when the driving force is released, etc., the structure is not only complicated, but also the clutch There was also a decrease in accuracy due to angular deviation in the disassociation and reconnection operation, and a decrease in holding force due to slippage due to wear and tear on the brake, making it impossible to operate accurately according to the preset program.

[Purpose of the invention]

The present invention eliminates the above-mentioned drawbacks, makes the device smaller, reduces rotational inertia, improves control responsiveness, and controls the screw back pressure such as mold clamping force and injection force according to the programmed motor torque control. An object of the present invention is to provide an injection molding machine that can perform the following steps.

[Key points of the invention]

In an injection molding machine in which the rotational motion of an electric motor is converted into linear motion or approximate linear motion by a screw transmission mechanism or link mechanism, or is directly transmitted to the drive system as rotational motion, in order to achieve the above-mentioned purpose, mold opening/closing, A rotor of an electric motor is integrally coupled to the rotary drive shaft of at least one operating drive system for each operation such as injection and screw rotation, and mold clamping injection output and screw back during plasticization or after plasticization are completed. The injection molding machine was designed such that the pressure was mutually controlled throughout the operating range by programmed torque control of an electric motor.

〔Example〕

Next, one embodiment of the present invention will be described with reference to FIG. 1. Reference numeral 11 is a screw fitted into the heating cylinder 12 so as to be rotatable and movable back and forth. Said screw 11
is integrally attached to the drive shaft 13 with a key 14 and a split collar 15. The stator coil 1 16 is integrally connected to the rotor 17 by a ball screw, so that the stator coil 1 is integrally disposed on the injection bracket 18.
It is rotated by the rotational force generated in response to changes in the magnetic field due to the control of energization to 9. The injection bracket rotatably supports the screw 11 and has a built-in mechanism for moving the screw 11 back and forth and rotating it, and is fixed to a base (not shown). A nut 20 is engaged with the ball screw 16, and a nut 20 is engaged with the ball screw 16.
It moves forward and backward on the same screw 16 as it rotates. Reference numeral 21 denotes a thrust box in which the nut 20 and thrust bearing 22 are housed, and is designed to receive the thrust load caused by the screw 11 and the thrust load caused by the forward movement of the nut 20 (moving to the left in the figure). Therefore,
When the ball screw 16 rotates, the nut 20 meshed with the screw 16 advances and retreats on the ball screw 16. When the nut 20 moves forward, the screw 11 moves forward, and when the nut 20 moves backward (moves to the right in the figure), the thrust box 21 moves forward. is connected to the drive shaft 13 via the drive shaft 13.
The screw 11, which is integrally attached to the screw 11, is pulled back. 23 is thrust box 2
This is a guide shaft that prevents the rotation of the nut 20 and the thrust box 21 due to the rotation of the screw described later. 24 is a rotor integrally attached to the drive shaft 13, and a fixed coil 2 is integrally attached to the thrust box 21.
The screw 11 is rotated by generating a rotational force in response to changes in the magnetic field caused by controlling the energization of the screw 5. 26 is a fixed die plate, and 27 is a movable die plate, to which a fixed die 28 and a movable die 29 are attached, respectively, so that when both die 28 and 29 are joined at the die joint surface A, a die cavity is formed. It's getting old. 30 is the movable die plate 27
When the nut 31 engaged with the screw shaft 30 attached to the screw shaft rotates, the screw shaft 30, that is, the movable die plate 27 moves forward and backward, and the molds 28 and 29 move forward and backward.
It is designed to open and close.

A rotor 32 is integrally attached to the nut 31 and is rotated by controlling the supply of electricity to a stator coil 34 integrally attached to an end plate 33. 35 is a brake shoe for locking the outer periphery of the screw shaft 30; 36 is a wedge for pressing the brake shoe 35 against the outer periphery of the screw shaft 30; 37 is the wedge 36 for locking the brake shoe 35;
This is an electric or hydraulic cylinder unit for pressing or releasing.

[Effect]

The structure is as described above, and its operation will be explained next. When the stator coil 34 attached to the end plate 33 is energized, the nut 31 to which the rotor 32 is attached rotates.
The screw shaft 30, that is, the movable die plate 27 moves forward (rightward in the figure), and the molds 28 and 29 are joined at the mold joint surface A. At this time, the energization to the stator coil 34 is controlled so that both the molds 28 and 29 are clamped with a predetermined pressing force, and when the molds 28 and 29 are joined, the cylinder unit 37 is closed. By pushing the wedge 36, the brake shoe 35 locks the screw shaft 30. Therefore, even if the stator coil 34 is de-energized, the necessary mold clamping force is maintained and does not loosen.

On the other hand, on the injection side, the drive shaft 13 to which the rotor 24 is attached, that is, the screw 11, is rotated by controlling the energization of the stator coil 25 integrally attached to the thrust box 21, thereby melting the material supplied from the hopper. While transferring the inside of the heating cylinder 12, the screw 1 is
The measurement is accumulated in front of 1. During this time, Sukuriyu 11
is at the retraction limit position, and when the mold clamping described above is completed,
It now moves forward to inject the metered material. (Moving to the left in the figure.) This forward movement rotates the ball screw 16 by controlling the energization of the stator coil 19 attached to the injection bracket 18, and the screw 1
Nut 20 that meshes with 6, that is, the screw 1 connected to this
1 is pushed forward (to the left in the figure). Injection is performed as described above, and when the material in the cavity has cooled and solidified, the cylinder unit 3
7 pulls out the wedge 36, and the brake shoe 35 unlocks the screw shaft 30. Next, the stator coil 34 is energized in the opposite direction to that during mold clamping, the screw shaft 30 moves back, and the mold opens. be exposed.

〔effect〕

As explained above, the mold opening/closing, injection operation, screw rotation operation, etc. are driven by an electric motor, and the rotary drive shaft of the operating drive system is the rotor of the electric motor, so the device is compact and has low rotational inertia. Not only the start and stop of the operation, but also the acceleration and deceleration control have good responsiveness, and since there is no action to connect or disconnect the drive system using a clutch, etc., the control operation of the electric motor etc. is directly transmitted to each operating axis, improving accuracy. Can be highly controlled. Furthermore, since each electric motor etc. is used exclusively for each operation, even if the speed or operating force of operations such as injection and mold opening/closing is controlled by a program, each operation may be held by an electromagnetic brake or driven by a clutch. Since connection and dissociation of the system are not involved, each program can be realized with high precision.
Its reproducibility has also improved.

Although the above embodiment is an example in which the rotor of the electric motor is integrally incorporated into the drive shaft of the injection molding machine, a structure in which a commercially available electric motor is directly connected to the drive shaft may also be used.

[Brief explanation of drawings]

FIG. 1 is a diagram showing one embodiment of the present invention. 11... Screw, 13... Drive shaft, 16...
Ball screw, 17, 25, 32...Rotor, 18
... Injection bracket, 19, 25, 34 ... Stator coil, 20, 31 ... Nut, 21 ... Thrust box, 22 ... Thrust bearing, 2
6... Fixed die plate, 27... Moving die plate, 30... Screw shaft, 33... End plate, 35... Brake shoe.

Claims (1)

[Scope of Claims] 1. A fixed die plate 26 to which a fixed die is fixed and a movable die plate 27 to which a movable die is fixed are arranged facing each other, and an end plate 33 fixed to the rear of the movable die plate 27 is further provided. The movable die plate 27 is reciprocated by a screw shaft 30 provided on the end plate 33 side, and a screw is disposed on the back surface of the fixed die plate 26 to move toward and away from the screw shaft 16, and the nut 31 and the screw shaft 16
In an electric injection molding machine that is driven by an electric motor, a stator coil 34 is fixed to an end plate 33, a nut 31 that is screwed onto a screw shaft 30 is rotatably provided at a position concentric with the stator coil 34, and 3
A rotor 32 is fixed to the outer periphery of the screw 11.
is rotatably supported by an injection bracket 18, a drive shaft 13 is fixed to the end of the screw 11, a rotor 24 is fixed to the outer periphery of this drive shaft 13, and a stator is mounted concentrically with this rotor 24. A thrust box 21 with a fixed coil 25 is provided, the thrust box 21 supports the screw 11 so as to be movable in the axial direction, the thrust box 21 fixes a nut 20, and the screw shaft 16 is screwed into the nut 20. A motor-driven injection molding machine characterized in that a rotor 17 is fixed to the end of a screw shaft 16, and a stator coil 19 wound around the injection box 18 is fixed.