JPH11198202A - Method for controlling movable board of electric injection molding machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To release mold clamping reaction force safely by loosening a movable plate to a mold touch position or an optional position which does not receive the mold clamping reaction force when an operation mode is changed over from on to off although a servo-motor for opening/closing a mold is receiving the reaction force of a mold clamping mechanism. SOLUTION: When an operation mode 'off' is input (S1), it is judged whether a mold board position is before a mold touch position or not (S2), when the position is in front of the touch position, it is judged that the reaction force of mold clamping force is received, and the mold board is retracted to the touch position (position which does not receive the reaction force) (S3). After that, the control of a servo-motor is made free (S4). When the mold board is behind the touch position (S2), the control of the servo-motor is made free at the position (540. In this way, a spring back phenomenon can be prevented when the operation mode is turned off without using a brake circuit and device.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling a movable plate of an electric injection molding machine in which a mold opening and closing mechanism is driven and controlled by a servomotor.

[0002]

2. Description of the Related Art The structure of a mold opening / closing device of a conventional electric injection molding machine will be described.

In FIG. 2, reference numeral 1 denotes a fixed plate, and a movable plate 2 is disposed opposite to the fixed plate 1, and a mold clamping housing 3 is disposed on the left side of the movable plate 2 in the drawing. . A fixed die 4 is fixed to the fixed platen 1, and a movable die 5 is fixed to the movable platen 2. A cavity 6 is formed between the fixed mold 4 and the movable mold 5. The fixed mold 4 has a sprue 7 serving as a resin passage, and the resin is injected and filled into the cavity 6 from the injection nozzle 8 via the sprue 7. A tie bar 9 is disposed through the fixed platen 1, the movable platen 2 and the mold clamping housing 3, and the position of the mold clamping housing 3 with respect to the fixed platen 1 is determined by tie bar nuts 10 screwed to both ends of the tie bar 9. .

[0004] A toggle device 12 connected to a crosshead 11 for moving the movable platen 2 back and forth is connected to the mold clamping housing 3 and the movable platen 2.

A ball nut 13 is fixed to the crosshead 11, and a ball screw 14 screwed to the ball nut 13 is fixed to the mold clamping housing 3 in a rotatable state. A pulley 15 is attached to an end of the ball screw 14 opposite to the crosshead 11. Also,
A servo motor 16 is fixed to the mold clamping housing 3, and a pulley 17 attached to the motor shaft is connected to a pulley 15 attached to the ball screw 14 by a timing belt 18.

When the servo motor 16 rotates,
The ball screw 14 rotates, the ball nut 13 and the crosshead 11 move integrally, and the movable platen 2 moves via the toggle device 12 to transmit the pressing force.

A driving device for the servo motor 16 includes a rotation detector 19 for detecting the position of the crosshead 11 attached to the servo motor 16, and a rotation detector 19 based on the position signal.
And a control device 21 for supplying a control current to the servomotor 16 via a driver amplifier.

When the operation mode switching is selected while the mold opening / closing device of the above-described electric injection molding machine is in a mold-clamped state, servo free or servo lock is usually performed on the spot.

[0009]

When the operation mode switching is selected and the control mode of the servomotor at that time is set to free, the movable platen moves in the mold opening direction due to the reaction force of the mold clamping mechanism. (Spring back phenomenon).

If the operation mode is erroneously selected while the mold is being clamped, such as during setup, the mold board is opened against the operator's will.

In order to prevent this phenomenon, the reaction force of the mold clamping mechanism is canceled by position control or a brake device on the spot. However, performing position control is not advisable in terms of safety. This is because the operation mode is turned off, but a current is applied to the servomotor for position control. Therefore, if the position control command is changed due to some abnormality of the device, it is not safe. Further, incorporating a brake device into an injection machine is not advantageous in terms of manufacturing cost.

Further, in the mold opening / closing device of the toggle mechanism, if the mold clamping state is left for a long time, the grease of the sliding portion in the mold clamping state may cause the mold to be unable to be opened. bad.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem. Even when the mold opening / closing device is in a mold-clamped state, the reaction force of mold clamping can be safely reduced when the operation mode is turned off. An object of the present invention is to provide a movable board control method for an electric injection machine that can be released.

[0014]

The present invention has solved the above-mentioned problems as follows.

As described above, when the mold plate is normally stopped in the mold clamping state, the reaction force of the mold clamping mechanism is applied to the mold opening / closing servomotor. In this state, when the operation mode is turned off and the apparatus is stopped, the stopping force of the motor is released at the moment of the stop, and the mold plate moves in the opening direction. Therefore, when the operation mode is selected from the start to the end even though the mold opening / closing servomotor receives the reaction force of the mold clamping mechanism, the movable platen is moved to the mold touch position,
Alternatively, a mold loosening operation of loosening the movable platen is performed to an arbitrary position that does not receive the reaction force of the mold clamping force, thereby safely releasing the reaction force of the mold clamping. After the mold release operation, the servo motor is set in a free state or a position control state.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described together with embodiments with reference to the drawings.

FIG. 1 is a flowchart showing the operation of the movable plate of the mold opening and closing device of the electric injection molding machine according to the present invention.
The configuration of the mold opening / closing device is the same as the configuration shown in FIG.

As shown in FIG. 1, when the operation mode "OFF" is input (step 1), the mold platen position (movable platen position) is set.
Is determined to be before the mold touch position (step 2). If it is before the mold touch position, it is determined that a reaction force of the mold clamping force has been received, and the mold touch position (reaction force The mold plate is retracted to a position where it is not received (step 3). After the mold plate has retracted to the mold touch position, the control state of the servomotor is set to free (step 4). If the die plate is located after the die touch position in the step 2, the control state of the servomotor is set to free at that position (step 4). In the above embodiment, in step 4,
Although the servomotor is in a free state, the servomotor may be in a position control state.

[0019]

According to the movable plate control method of the present invention,
The springback phenomenon when the operation mode is switched off can be prevented without using a conventional brake circuit or device. Also, the servo motor control state after the mold loosening operation, even in the position control state, since the reaction force of the mold clamping mechanism has already been released, the motor control power is less than when the reaction force is generated. . Even if the power is turned off in this state, the mold board will not open unexpectedly, which is safe.

Further, the mold loosening operation is not a mold opening operation due to a natural phenomenon such as springback, but a mold opening operation to a position where a reaction force is released, so that the mold does not actually open.

[Brief description of the drawings]

FIG. 1 is a flowchart showing the operation of a movable plate of a mold opening and closing device of an electric injection molding machine according to the present invention.

FIG. 2 is an overall configuration diagram of a mold opening / closing device of an electric injection molding machine using the movable platen control method according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fixed board 2 Movable board 3 Mold clamping housing 4 Fixed mold 5 Movable mold 6 Cavity 11 Cross head 12 Toggle device 13 Ball nut 14 Ball screw 15, 17 Pulley 16 Servo motor 19 Rotation detector 20 Driver amplifier 21 Control device

Claims (3)

[Claims] 1. A method for controlling a movable platen of an electric injection molding machine in which a mold opening / closing mechanism is drive-controlled by a servomotor (16),
When the operation mode is selected from the start to the end even though the mold opening / closing servomotor (16) is receiving the reaction force of the mold clamping mechanism, the movable platen (2) is moved to the mold touch position or the mold clamping. A movable board control method for an electric injection molding machine, wherein the movable board is opened to a position where it is not subjected to a reaction force. 2. The method for controlling a movable platen of an electric injection molding machine according to claim 1, wherein the servomotor (16) is set in a free state after the movable platen (2) is opened. 3. The method for controlling a movable plate of an electric injection molding machine according to claim 1, wherein after opening the movable plate, the servomotor is brought into a position control state.