JPH10151650A - Control of mold clamping apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily alter mold clamping force and to control mold clamping force during molding. SOLUTION: The position of a movable platen 12 is detected by a position detector 41 while the movable platen 12 is allowed to advance and, when an electromotor is driven on the basis of the difference between the detected position of the movable platen 12 and the position set by a position setting device and a fixed mold 15 and a movable mold 16 are brought to a contact state to complete mold clamping, a current is supplied to an electromagnet 18 to generate mold clamping force and the mold clamping force is detected by a load detector 40 and the current supplied to the electromagnet 18 is controlled on the basis of the difference between the detected mold clamping force and the mold clamping force set by a mold clamping force setting 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 mold clamping device.

[0002]

2. Description of the Related Art Conventionally, in an injection molding machine, a molded product can be obtained by injecting a resin from an injection nozzle of an injection device, filling the resin into a cavity space of a mold device, and solidifying the resin. Has become. The mold device includes a fixed mold, a movable mold disposed to be able to advance and retreat with respect to the fixed mold, and moving the movable mold to close, close, and clamp the mold device. It has a mold clamping device for opening the mold.

[0003] The mold clamping apparatus includes a hydraulic mold clamping apparatus driven by supplying oil to a hydraulic cylinder and an electric mold clamping apparatus driven by an electric motor. Tightening devices are increasingly being used because they are not only highly controllable, but also clean and energy efficient. In this case, the electric motor is driven to rotate the ball screw to generate a thrust, and the thrust is expanded by a toggle mechanism to generate a large mold clamping force.

[0004]

However, in the conventional electric type mold clamping device, a toggle mechanism is used, so that it is difficult to change the mold clamping force due to the characteristics of the toggle mechanism. In addition, the responsiveness and stability are reduced, and the mold clamping force cannot be controlled during molding. Therefore, there has been provided a mold clamping device that can directly use a thrust generated by a ball screw as a mold clamping force. In this case, since the torque of the electric motor is proportional to the mold clamping force, the mold clamping force can be controlled during molding.

However, in order to generate the mold clamping force, it is necessary to constantly supply a current to the motor, and the power consumption and heat generation of the motor increase. Therefore, it is necessary to increase the rated output of the electric motor, which increases the cost of the mold clamping device. The present invention solves the problems of the conventional mold clamping device, can easily change the mold clamping force, can control the mold clamping force during molding, and reduce the rated output of the electric motor. An object of the present invention is to provide a method of controlling a mold clamping device which can be reduced in size and cost of the mold clamping device.

[0006]

For this purpose, in the control method of the mold clamping apparatus according to the present invention, the position of the movable platen is detected by a position detector while the movable platen is advanced, and the detected position of the movable platen is determined. The motor is driven based on the difference from the position command set by the position setting device, and when the fixed mold and the movable mold come into contact and mold closing is completed, current is supplied to the electromagnet to generate mold clamping force. And
The mold clamping force is detected by a load detector, and a current supplied to the electromagnet is controlled based on a difference between the detected mold clamping force and a mold clamping force command set by the mold clamping force setting device.

[0007]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a diagram showing a mold opening state of the mold clamping device according to the embodiment of the present invention, and FIG. 2 is a diagram showing a mold clamping state of the mold clamping device according to the embodiment of the present invention. In the figure, reference numeral 11 denotes a fixed platen, a rear platen 13 is disposed at a predetermined distance from the fixed platen 11, and four tie bars 14 (in the figure, four tie bars 14) are provided between the fixed platen 11 and the rear platen 13.
Only two tie bars 14 are shown. ) Is erected. The movable platen 12 is disposed so as to be movable forward and backward along the tie bar 14 so as to face the fixed platen 11. In this case, a position sensor 41a is provided on the movable platen 12, and a detected bar 41b is provided on the rear platen 13, and the mark on the detected bar 41b is read by the position sensor 41a. The position can be detected. The position sensor 41 is composed of the position sensor 41a and the detected bar 41b.

In the present embodiment, a position sensor 41a is provided on the movable platen 12, and a detection bar 41b is provided on the rear platen 13. However, the position sensor 41a is provided on the movable platen 12. Alternatively, the detection bar 41b may be provided on the fixed platen 11 to detect the position of the movable platen 12 with respect to the fixed platen 11.

A fixed mold 15 is fixed to the fixed platen 11 and a movable mold 16 is fixed to the movable platen 12. The fixed mold 15 and the movable mold 16 are moved as the movable platen 12 advances and retreats. Are brought into and out of contact with each other. In addition,
When the fixed mold 15 and the movable mold 16 are brought into contact with each other, a cavity space (not shown) is formed between the fixed mold 15 and the movable mold 16, and the cavity space is filled with resin as the resin is injected. .

An electromagnet 18 is fixed to the rear surface (left side in the figure) of the rear platen 13. The electromagnet 18 includes an electromagnetic laminated steel sheet 19, an electromagnet frame 20 for fixing the electromagnetic laminated steel sheet 19 to the rear platen 13, and a magnetomotive force. From the coil 21 that generates And the electromagnet 18
The suction plate 22 is disposed so as to be movable along the rail 51. The suction plate 22 includes an electromagnetic laminated steel plate 52 and an adsorption plate frame 23 that supports the electromagnetic laminated steel plate 52. In addition, 54 is a linear guide.

In the present embodiment, the rear platen 1
The electromagnet 18 is fixed to the back of the rear plate 3 and the suction plate 22 is movably disposed.
2 can be fixed and the electromagnet 18 can be disposed movably. The suction plate 22 has a cylindrical pressure piston 1.
7 is fixed at the rear end (left end in the figure), and the pressurizing piston 17 extends toward the fixed platen 11, and the electromagnet 1
8 and the rear platen 13, and the front end (right end in the figure) is fixed to the movable platen 12 via the load detector 40. Therefore, as the suction plate 22 moves, the movable platen 12 also moves forward and backward. Further, after the mold closing is completed, when the mold is closed, the load detector 40 is closed.
Thus, the mold clamping force can be detected.

A mold thickness adjusting nut 24 is disposed between the suction plate frame 23 and the pressure piston 17, and the mold thickness adjustment nut 24 is rotatably supported by the suction plate frame 23. Further, in the axial direction (the mold opening and closing direction), it is restrained by the suction plate frame 23 and is moved forward and backward together. The mold thickness adjusting nut 24 and the pressurizing piston 17 are screwed together, and by rotating the mold thickness adjusting nut 24 via the gear 25, the position of the suction plate 22 with respect to the pressurizing piston 17 is changed. Can be adjusted. Therefore, the gap between the electromagnet 18 and the attraction plate 22 can be set to an optimum value in accordance with the thickness of the fixed mold 15 and the movable mold 16, and a sufficiently large mold clamping force can be generated.

When a current is supplied to the coil 21, the attraction plate 22 is moved by the attraction force of the electromagnet 18 to the electromagnet 1
Sucked in 8. In this case, since the electromagnet 18 is provided with the electromagnetic laminated steel plate 19 and the suction plate 22 is provided with the electromagnetic laminated steel plate 52, the responsiveness and stability of the mold clamping device at the time of suction can be improved. The pressurizing piston 17
A ball nut 56 is fixed to the inner periphery of the rear end, and the ball nut 56 and the ball screw 26 are screwed together. The ball nut 56 and the ball screw 26 constitute a movement direction changing means. In this case, the ball screw 26 is generated by a servomotor 27 as an electric motor.
Is transmitted to the pressure piston 17 after being converted into a linear motion by the motion direction converting means. For this purpose, the rear end of the ball screw 26 is
8 and rotatably supported by the molding machine frame 29 and connected to the servomotor 27. The front end of the ball screw 26 is
Is allowed to enter. Further, a rotation angle detector 42 is connected to a motor shaft (not shown) of the servo motor 27, so that the rotation angle of the servo motor 27 can be detected by the rotation angle detector 42.

In the present embodiment, the ball screw 26 and the servomotor 27 are directly connected, but may be connected via a not-shown pulley, belt, or the like. A control device (not shown) is provided in the mold clamping device having the above configuration, and the control device can perform mold opening / closing control and mold clamping force control. In the mold opening / closing control, the movable mold 16 is moved forward (moved to the right in the figure) from the mold opening limit position shown in FIG. The position control and speed control of the movable platen 12 are performed. Also,
In the mold clamping force control, as shown in FIG. 2, after the movable mold 16 comes into contact with the fixed mold 15, the fixed mold 15 is continuously pressed, and during the mold clamping until the mold opening is started,
A mold clamping force is generated and adjusted.

To this end, the control device is provided with a mold opening / closing control section and a mold clamping force control section. FIG. 3 is a block diagram of a mold opening / closing control unit of the control device according to the embodiment of the present invention. In the figure, 27 is a servomotor, 41 is a position detector, 43 is a position setting device, 44 is a servo controller, 6
1 is a subtractor.

The position setting device 43 sets and outputs position commands for closing and opening the mold based on the mold opening position and the set speed set by the operator. Then, the subtractor 61 obtains a difference between the position of the movable platen 12 (FIG. 1) detected by the position detector 41 and the position command, and outputs the difference to the servo controller 44.
The servo controller 44 drives the servomotor 27 in accordance with the difference, rotates the ball screw 26, and moves the movable platen 12 to a target position corresponding to the position command. In this manner, the mold opening / closing control section can perform feedback control of the position of the movable platen 12.

FIG. 4 is a block diagram of a mold clamping force control unit of the control device according to the embodiment of the present invention. In the figure, 1
8 is an electromagnet, 40 is a load detector, 45 is a mold clamping force setting device,
46 is an electromagnet controller, and 62 is a subtractor. The mold clamping force setting device 45 sets and outputs a mold clamping force command based on the mold clamping force and the operation time set by the operator. Then, the subtracter 62 obtains a difference between the mold clamping force detected by the load detector 40 and the mold clamping force command, and outputs the difference to the electromagnet controller 46. The electromagnet controller 46 controls the electromagnet 18 in accordance with the difference.
To generate a target mold clamping force corresponding to the mold clamping force command. As described above, the mold clamping force control section can perform feedback control of the mold clamping force.

Next, the operation of the mold clamping device having the above configuration will be described. In the state of FIG. 1, a mold clamping signal is generated by the control device, and the mold opening / closing control unit is activated,
The position setting device 43 outputs a position command at the time of closing the mold based on the mold closing position and the set speed set by the operator. Further, the subtractor 61 obtains a difference between the position of the movable platen 12 detected by the position detector 41 and the position command, and outputs the difference to the servo controller 44.

Then, the servo controller 44 drives the servo motor 27 in the positive direction in accordance with the difference,
When the ball screw 26 is rotated forward, the ball nut 56 screwed with the ball screw 26 is advanced, and with the advance of the ball nut 56, the pressurizing piston 17 and the suction plate 22 are advanced. The movable platen 12 is advanced, and the mold is closed. Subsequently, as shown in FIG. 2, when the fixed mold 15 and the movable mold 16 come into contact with each other, the mold closing is completed, the difference becomes zero, the servomotor 27 is stopped, and the movable platen 12 is also stopped. Let me do. The force required for closing the mold is sufficiently smaller than the mold clamping force. When the fixed mold 15 and the movable mold 16 come into contact with each other, the movable mold 16 is decelerated so that the fixed mold 15 and the movable mold 16 are not damaged.

In the present embodiment, the position detector 41
Thus, the position of the movable platen 12 is detected, and the mold opening / closing control is performed based on the detected position and the position command. The rotation angle detector 42 provided in the servomotor 27 detects the rotation angle. It is also possible to perform mold opening / closing control based on the detected rotation angle and the detected angle command.

When the mold closing is completed, the pressurizing piston 17 is moved by the mold thickness adjusting nut 24 so that a constant gap is formed between the electromagnet 18 and the attraction plate 22.
Is adjusted in advance. Next, when the mold closing is completed and the gap between the movable mold 16 and the fixed mold 15 enters a certain range at the contact position, the mold clamping force control unit is activated, and the mold clamping force setting is performed. Table 45
Outputs a mold clamping force command based on the mold clamping force and the operation time set by the operator. Further, the subtractor 6
In 2, the difference between the mold clamping force detected by the load detector 40 and the mold clamping force command is obtained, and the difference is output to the electromagnet controller 46.

The electromagnet controller 46 controls the current supplied to the electromagnet 18 in accordance with the difference, generates an attractive force by the electromagnet 18, and
Aspirate 2. The attractive force of the electromagnet 18 is
2. The suction plate frame 23, the mold thickness adjusting nut 24, the pressurizing piston 17, and the movable platen 12 are sequentially transmitted to form a mold clamping force, and the movable mold 16 is fixed to the fixed mold 1 by the mold clamping force.
5 and the mold is clamped. This state is maintained until the mold is opened.

In this case, the mold clamping force can be changed during molding by changing the value of the current supplied to the coil 21. Since the mold clamping force is received by the pressurizing piston 17 and is not applied to the ball screw 26, the ball screw 26 can be made as strong as necessary for closing the mold. Therefore, the cost of the mold clamping device can be reduced, and the durability can be improved.

Further, since the mold clamping force is generated solely by the attraction force of the electromagnet 18, even if torque ripple occurs in the servomotor 27, the mold clamping force does not fluctuate. Further, at the time of mold clamping, no current is supplied to the servomotor 27 and the servomotor 27 is stopped, so that the power consumption and the heat generation of the servomotor 27 can be reduced. As a result, the rated output of the servomotor 27 can be reduced, and the cost of the mold clamping device can be reduced.

Subsequently, when a resin is filled in a cavity space (not shown), the resin is cooled and solidified, a mold opening signal is generated by the control device, and the mold clamping force setting device 45 operates within a time set by the operator. The mold clamping force before opening is 0
A mold clamping force command is output such that Further, the subtractor 62 calculates a difference between the mold clamping force detected by the load detector 40 and the mold clamping force command, and outputs the difference to the electromagnet controller 46.

Then, the electromagnet controller 46 controls the current supplied to the electromagnet 18 in accordance with the difference, makes the attraction force zero, and releases the suction plate 22. As a result, the mold clamping force also becomes zero. When the mold clamping force falls below a certain value, the mold opening / closing control section is activated, and the position setting device 4
Reference numeral 3 outputs a position command when the mold is opened based on the mold opening position and the set speed set by the operator. Also,
In the subtractor 61, a difference between the position of the movable platen 12 detected by the position detector 41 and the position command is obtained, and the difference is output to the servo controller 44.

Then, the servo controller 44 drives the servo motor 27 in the reverse direction in accordance with the difference,
When the ball screw 26 is rotated in the reverse direction, the ball nut 56 screwed with the ball screw 26 is retracted, and with the retraction of the ball nut 56, the pressure piston 17 and the suction plate 22 are retracted (left in FIG. 1). 1), the movable platen 12 is further retracted, and as shown in FIG. 1, the fixed mold 15 and the movable mold 16 are separated, and the mold is opened.

The present invention is not limited to the above embodiment, but can be variously modified based on the gist of the present invention, and they are not excluded from the scope of the present invention.

[0029]

As described above in detail, according to the present invention, in the method of controlling the mold clamping device, the position of the movable platen is detected by the position detector while the movable platen is advanced, and the detected movable position is detected. The motor is driven based on the difference between the position of the platen and the position command set by the position setting device, and when the fixed mold and the movable mold come into contact and mold closing is completed, current is supplied to the electromagnet to form the mold. A clamping force is generated, and the mold clamping force is detected by a load detector and supplied to the electromagnet based on a difference between the detected mold clamping force and a mold clamping force command set by the mold clamping force setting device. Control the current flow.

In this case, when the mold is closed, the electric motor is driven and the movable platen is advanced. At this time, the position of the movable platen is detected by a position detector,
The electric motor is driven based on the difference between the detected position and the position command set by the position setting device, and when the fixed mold and the movable mold come into contact with each other, the mold closing ends. Next, a current is supplied to the electromagnet to generate a mold clamping force. At this time, the mold clamping force is detected by the load detector, and the current supplied to the electromagnet is controlled based on the difference between the detected mold clamping force and the mold clamping force command set by the mold clamping force setting device. Is done.

Therefore, by changing the value of the current supplied to the electromagnet, the mold clamping force can be changed during molding. Further, at the time of mold clamping, no current is supplied to the electric motor and the electric motor is stopped, so that the power consumption and the heat generation of the electric motor can be reduced. As a result, the rated output of the electric motor can be reduced, and the cost of the mold clamping device can be reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing a mold opening state of a mold clamping device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a mold clamping state of the mold clamping device according to the embodiment of the present invention.

FIG. 3 is a block diagram of a mold opening / closing control unit of the control device according to the embodiment of the present invention.

FIG. 4 is a block diagram of a mold clamping force control unit of the control device according to the embodiment of the present invention.

[Explanation of symbols]

 12 movable platen 15 fixed mold 16 movable mold 18 electromagnet 27 servo motor 40 load detector 41 position detector 43 position setting device 45 mold clamping force setting device

Claims (1)

[Claims] (A) detecting the position of a movable platen by a position detector while advancing the movable platen; (b)
Drive the motor based on the difference between the detected position of the movable platen and the position command set by the position setting device,
(C) When the fixed mold and the movable mold come into contact with each other to close the mold, a current is supplied to the electromagnet to generate a mold clamping force, and the load detector detects the mold clamping force. d) A method of controlling a mold clamping device, comprising controlling a current supplied to an electromagnet based on a difference between a detected mold clamping force and a mold clamping force command set by a mold clamping force setting device.