JP2653754B2 - Mold opening / closing control method for molding machine - Google Patents

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 the opening and closing of a mold of a molding machine, and more particularly to a molding machine having a mold clamping cylinder for clamping a mold and an auxiliary cylinder for opening and closing the mold. In the mold opening and closing control method.

[0002]

2. Description of the Related Art Conventionally, as an opening / closing operation of a mold in a molding machine, for example, an injection molding machine, the mold is moved at a high speed by an auxiliary cylinder, and the mold is clamped at a position near the end of the high-speed moving region. It is known to shift to a mold clamping operation using a cylinder.

[0003] The former high-speed movement of the mold by the auxiliary cylinder is performed by using the position of the mold as a control factor to open-control the hydraulic oil pressure supplied to the auxiliary cylinder based on this information. The mold clamping operation by the mold clamping cylinder is such that after the mold reaches a predetermined position, the hydraulic oil is supplied to the mold clamping cylinder by a feedback signal such as mold speed information, position information, and mold clamping pressure. This is performed by performing closed control on the supplied servo valve.

[0004] By such a two-stage operation, the simple movement of the mold is performed at a high speed by the auxiliary cylinder, and the operation of the servo valve is performed at the time of mold clamping which requires the accuracy of position and pressure management. In addition, by performing high-precision control by closed control using an analog servo, the opening / closing time is minimized while securing the mold clamping accuracy of the mold.

[0005]

However, such a conventional technique has the following problems to be improved. That is, in the prior art, as shown in FIG. 1, first, the movement of a mold is started by supplying a set flow rate of hydraulic oil to an auxiliary cylinder, and the mold is moved by the hydraulic oil. The predetermined speed is set after a certain time has elapsed from the start of the supply. Then, when the mold is moved to a predetermined position, based on the position information, a pump for pumping hydraulic oil is controlled to be open,
The movement speed of the mold is reduced by reducing the supply amount of the hydraulic oil, and further, the supply amount of the hydraulic oil is kept constant at the time when the mold reaches a predetermined position. The speed is kept constant at low speed.

When the mold is further moved to a predetermined position (control switching point indicated by A in FIG. 1) in such a low speed state, the operation of moving the mold by the auxiliary cylinder is stopped, and The operation is shifted to the mold clamping operation by the mold clamping cylinder. Then, in this mold clamping operation, the servo valve for supplying the hydraulic oil to the mold clamping cylinder performs speed control by closed control by analog servo using the speed of the mold as a feedback signal, and thereafter, feeds back position information. Through position control by closed control as a signal, pressure control by closed control using the mold clamping pressure as a feedback signal is performed.

Here, the movement of the mold is performed by the open control as described before up to the control switching point A, and the servo valve is not operated. When the control switching point A is reached and closed control is started, since the control of the servo valve is control by analog servo, the operation start position (opening at the time of control start) of the servo valve is unknown. The control is started from the state of the opening degree 0. On the other hand, the mold is continuously moved at the speed even when the control switching point A is reached. In this state, when the supply of the hydraulic oil is switched from the auxiliary cylinder to the mold clamping cylinder, the servo valve is moved. Since the opening degree is 0, the supply of hydraulic oil to the mold closing cylinder does not match the moving speed of the mold described above, and as a result, the mold is rapidly decelerated, and the molding machine There is a problem that an impact is given.

In order to solve such a problem, it is conceivable to temporarily stop the movement of the mold as shown by B in FIG. The cycle becomes longer, which leads to a decrease in productivity.

Further, when the mold is opened, since the movement of the mold at the end of the mold opening is controlled by the open control of the auxiliary cylinder, there is a problem that the control accuracy of the stop position is low. The positional relationship with the unloader is not constant, which is an obstacle to its automation.

The present invention has been made in view of the above-mentioned conventional problems, and provides a mold opening / closing control method capable of reducing an impact force at a switching point between open control and closed control during opening / closing operation of a mold. It is another object of the present invention to provide a mold opening / closing control method for a molding machine that can accurately perform a stop position of a mold when the mold is opened.

[0011]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, the present invention provides a molding machine having a mold clamping cylinder for clamping a mold and an auxiliary cylinder for opening and closing the mold. A mold opening / closing control method, wherein a moving speed of a mold is detected during a mold opening / closing process by the opening control of the auxiliary cylinder, and a valve opening degree of a servo valve provided in parallel with the mold closing cylinder is determined. Adjustment is made in accordance with the moving speed, supply of hydraulic oil to the servo valve is stopped, and when the mold is moved to near the end of the mold opening / closing process, hydraulic oil is supplied to the servo valve. And the first half of the speed control by the servo valve is performed by open control. Then, the speed control by the servo valve is performed by using the speed information of the mold as a feedback signal. Characterized by closed control by a servo.

[0012]

According to the method for controlling the opening and closing of the mold of the molding machine according to the present invention, the moving speed of the mold moved by the auxiliary cylinder is detected at the time of closing the mold, and the valve opening degree corresponding to the moving speed is detected. Hydraulic oil is supplied to the mold closing cylinder via the servo valve when the operation of moving the mold by the auxiliary cylinder is completed. At this time, since the servo valve has a valve opening corresponding to the moving speed of the mold, the amount of hydraulic oil supplied to the mold closing cylinder is adjusted to an amount corresponding to the moving speed of the mold. Thus, the change in the moving speed of the mold is suppressed. Therefore, the smooth movement of the mold is continuously performed, and the impact on the mold and other components of the molding machine is suppressed.

Further, for a while after the supply of the hydraulic oil to the mold clamping cylinder is performed, the control of the servo valve for adjusting the supply amount of the hydraulic oil is performed as an open control. Or position, or mold clamping is performed by closed control using the mold clamping pressure as a feedback signal, so that during the open control, fluctuations in pressure of hydraulic oil supplied to the mold clamping cylinder are suppressed, and closed control is performed. Is performed with high accuracy.

Further, since the servo valve is controlled by digital servo, the opening of the servo valve is uniquely detected. Therefore, the opening degree is adjusted with high accuracy, and from this point also, the impact at the time of shifting from the above-described open control to closed control is reduced.

On the other hand, at the time of opening the mold, after the mold clamping cylinder is depressurized by the servo valve, the supply of hydraulic oil to the auxiliary cylinder is performed by open control, and the mold moves in the opening direction. Let me do. And
When the mold is moved to the vicinity of the stop position, the opening of the servo valve is adjusted to supply the amount of hydraulic oil corresponding to the moving speed to the mold clamping cylinder, and the mold is moved to a predetermined position. At this point, the hydraulic oil is supplied from the servo valve to the mold clamping cylinder, and the servo valve is closed-controlled, whereby the die is position-controlled with high precision and stopped at a predetermined position. .

[0016]

An embodiment of the present invention will be described below.
First, prior to the description of the method of the present invention, an example of a mold clamping device capable of effectively implementing the present invention will be described. In FIG.
Reference numeral 1 denotes a mold clamping device of a molding machine to which the present invention is applied. The mold clamping device 1 opens and closes a movable platen 2 to which a movable mold (not shown) is attached. A mold clamping ram 3 fixed to the panel 2 and the mold clamping ram 3
Are inserted, and a pair of hydraulic chambers 5a and 5b are formed by a first piston 4 provided at a substantially intermediate portion thereof.
And an auxiliary cylinder in which a pair of hydraulic chambers 7a and 7b are formed by a second piston 6 provided at the other end of the clamping ram 3 while the clamping ram 3 is inserted therethrough. 7, a servo valve 8 for controlling hydraulic oil supplied to the mold clamping cylinder 5, a bypass valve 9 for communicating and shutting off both hydraulic chambers 5 a and 5 b of the mold clamping cylinder 5, and a servo valve 8. A check valve 11 interposed between a P port and a tank 10, a mold on-off valve 12 for controlling hydraulic oil supplied to the auxiliary cylinder 7, and a digital servo control for controlling the servo valve 8 The device 13 is schematically configured.

The digital servo controller 13 detects the clamping force by detecting the pressure in both hydraulic chambers 5a and 5b of the clamping cylinder 5 with a differential amplifier 14,
The output of the differential amplifier 14 is transmitted to the digital servo operation processing unit 24 via the A / D converter 15. And
The position information obtained by the position detector 17 of the movable platen 2 and the speed information obtained by the speed converter 18 are also transmitted to the digital servo arithmetic processing unit 24. Furthermore, a pressure command 2 started by a main controller (not shown)
5. The speed command 26, the position command 27, and the control mode command 28 are also transmitted to the digital servo calculation processing unit 24. Thus, according to each control mode, the operation amount without any deviation from the command value is calculated by a predetermined algorithm, and the calculation result is supplied to the control amplifier 23 via the D / A converter 22 and amplified. This is supplied to the servo valve 8 as an operation amount.

Next, the method of controlling the opening and closing of the mold according to the present embodiment will be described together with the operation of the mold clamping device 1 thus configured.

First, when a mold clamping command is issued, the hydraulic pump is operated, and a driving signal is output to the mold opening / closing valve 12 to supply hydraulic oil to the auxiliary cylinder 7. At this time, the bypass valve 9 mounted on the mold clamping cylinder 5 is maintained in an ON state as shown in FIG. 3, and the two hydraulic chambers 5a and 5b of the mold clamping cylinder 5 are in communication with each other. The flow of hydraulic oil between the hydraulic chambers 5a and 5b is free, the movement of the first piston 4 is free, and the switching valve 29 is turned off to stop the supply of hydraulic oil to the servo valve 8. Have been. Thereby, the movable platen 2 is moved in the mold clamping direction.

When the movable platen 2 is moved by the auxiliary cylinder 7, the hydraulic pump is opened and the discharge amount of the hydraulic oil from the hydraulic pump is adjusted to a predetermined amount, as shown in FIG. As described above, after the movable platen 2 is rapidly accelerated, it is moved at a high speed at a predetermined speed (hereinafter, this region is referred to as a high-speed closed region).

When passing through such a high-speed closed area,
The discharge amount of the hydraulic pump is reduced based on the position signal from the position detector 17 so that the movable plate 2
Is decelerated to a predetermined speed, and is then moved by a predetermined distance at the decelerated predetermined speed (hereinafter, this area is referred to as a low-speed closed area).

Then, when the movable platen 2 reaches the low-speed closed region from the high-speed closed region, the speed of the movable platen 2 at this time is continuously changed by the speed converter 18 based on the signal from the position detector 17. The speed signal is output to the digital servo calculation processing unit 24, and the operation amount calculated by the digital servo calculation processing unit 24 is transmitted from the speed control unit 19 to the digital switch 21, D / A.
The opening degree of the servo valve 8 is output to the servo valve 8 through the converter 22 and the control amplifier 23 so that the servo valve 8 ensures the supply of the working oil amount corresponding to the speed of the movable platen 2. , Is continuously adjusted according to the deceleration state of the movable platen 2. Also at this time, the switching valve 29 is kept OFF, and the supply of the hydraulic oil to the servo valve 8 is not performed.

In this state, when the movable platen 2 continues to move and is moved to a predetermined position (ie, the control switching point A), the mold opening / closing valve 12 is closed, and the two hydraulic chambers 7a and 7b of the auxiliary cylinder 7 are closed. In addition to the communication with the tank 10, the bypass valve 9 is closed to shut off the communication between the two hydraulic chambers 5 a and 5 b of the mold clamping cylinder 5, and at the same time, the supply of hydraulic oil to the mold clamping cylinder 5 via the servo valve 8 is performed. When started, the speed control by the digital servo controller 13 is started.

Here, the amount of hydraulic oil supplied to the mold clamping cylinder 5 is determined by the opening of the servo valve 8.
Since the opening of the servo valve 8 is adjusted to an opening that secures the amount of hydraulic oil corresponding to the speed of the movable platen 2 and is in a standby state, the amount of hydraulic oil supplied to the mold closing cylinder 5 Is an amount that holds the moving speed of the movable platen 2. In addition, since the servo valve 8 is controlled by digital servo, the opening of the servo valve 8 is also accurately grasped, and the above-described opening adjustment is performed with high accuracy.

The opening of the servo valve 8 for supplying the hydraulic oil amount corresponding to the speed of the movable platen 2 can be obtained by the following three equations. The relationship between the flow rate of the working oil flowing through the servo valve 8 and the speed of the movable platen 2 is as follows: Q = Vf × S (1) Here, Q: servo valve flow rate corresponding to the current speed of the movable platen Vf; current speed of the movable platen S: pressure receiving area of the first piston 4 of the mold clamping cylinder 5 Also, the flow rate Q and the opening degree of the servo valve 8 Is given by: Q = CA × √ (2ΔP ÷ 2ρ) (2) However, C: flow rate counting of the servo valve 8 A: opening degree of the servo valve 8 ΔP: differential pressure of the servo valve 8 ρ: viscosity of hydraulic oil Therefore, A = (Vf × S) / ｛ C × √ (2ΔP ÷ 2ρ )｝ ・ ・ ・ ・ (3)

Such speed control is performed by open control by the open control unit 30 in the first half until the movable platen 2 reaches a predetermined position (this area is controlled by open control as shown in FIG. 3). Region O).
The provision of such an open control area O is for stabilizing the pressure fluctuation of the hydraulic oil supplied through the servo valve 8 because the pressure fluctuates in the initial stage of the supply. It is.

On the other hand, as described above, when the bypass valve 9 is closed, the pressure in the high-pressure side hydraulic chamber 5a decreases due to the inertial force of the first piston 4, and the movement of the hydraulic oil transiently stops. Although it becomes stable, in this embodiment, P
Since the check valve 11 is provided between the port and the tank 10, when the pressure fluctuates, the hydraulic oil flows from the tank 10 via the check valve 11 to the P of the servo valve 8.
By being sucked up to the port, the aforementioned pressure drop is suppressed, and the unstable movement of the hydraulic oil is stabilized at an early stage.

After passing through such an open control area O, the control is shifted to the speed control by the closed control, the switching valve 29 is opened, and the pressure oil is supplied to the servo valve 8. Therefore, the impact at the time of switching from the open control area O to the closed control area C is sufficiently mitigated by the operation of the servo valve 8 and the check valve 11, and all subsequent control is performed by the closed control. In the speed control by the closed control, the moving speed of the movable member 2 is calculated by the speed converter 18 based on the position signal from the position detector 17, and the moving speed is used as a feedback signal by the digital servo calculation processing unit 24. The digital servo arithmetic processing unit 24 compares the previously input speed command 26 with the feedback signal to generate a correction signal. Then, this correction signal is transmitted to the speed control unit 1.
9, output to the servo valve 8 via the digital switch 21, the D / A converter 22, and the control amplifier 23, whereby the movable member 2 is closed-controlled to a preset speed.

After such speed control is completed, the movable platen 2 is subjected to position control by closed control based on the position information from the position detector 17 and the position command 27 in the same manner as in the prior art. A / D from dynamic amplifier 14
The process is shifted to pressure control for controlling the mold clamping pressure and the like based on the mold clamping pressure information and the pressure command 25 input via the converter 15, and these control signals are transmitted to the position detector 17.
The signal is switched by the digital switch 21 based on the positional information from the servo valve 8 and output to the servo valve 8.

Next, the mold opening operation will be described. First, as shown in FIG. 4, the pressure of the hydraulic oil supplied to the mold clamping cylinder 5 is released from the mold clamping state by the closed controlled servo valve 8, and thereafter, the servo valve 8 is turned off. As a result, the bypass valve 9 is operated and the two hydraulic chambers 5 a and 5
b is communicated.

Next, the working oil adjusted to a predetermined amount by the open-controlled pump is supplied to the auxiliary cylinder 7, and the movable member 2 is moved at a low speed in the mold opening direction by the auxiliary cylinder 7. The region is shown as an initial mold opening region in FIG. 4), and when moved to a predetermined position, is moved at a high speed in the opening direction by increasing the supply amount of hydraulic oil from the pump. (This area is shown in FIG. 4 as a high speed mold open area). Through such a high-speed mold opening region, the movable platen 2 is its
Approaching the stop position, the supply amount of the hydraulic oil from the pump is reduced, so that the movable platen 2 is decelerated to a predetermined speed as shown in FIG.

When the low speed mold opening area is reached, the servo valve 8 controls the speed of the movable platen 2 based on the speed information of the movable platen 2 detected based on the signal from the position detector 17. The opening is adjusted to such an extent that the appropriate amount of hydraulic oil can be supplied to the mold clamping cylinder 5, and the standby state is established.

When the movable platen 2 reaches the predetermined position, the hydraulic chambers 7a and 7b of the auxiliary cylinder 7 are connected to the tank 10 by the mold opening / closing valve 12, and the hydraulic oil is supplied to the auxiliary cylinder 7 by the pump. Is stopped, the communication between the hydraulic chambers 5a and 5b of the mold clamping cylinder 5 by the bypass valve 9 is cut off, and the switching valve 29 is turned on. In this state, the servo valve 8 is turned on. The operation oil is supplied to the controller and the operation is shifted to the speed control by the servo valve 8.

At the time of shifting to such speed control, the opening degree of the servo valve 8 is set such that the supply of hydraulic oil corresponding to the speed of the movable platen 2 can be performed already, as in the case of mold clamping. Since the opening degree is adjusted, the moving speed of the mold clamping cylinder 5 operated by the hydraulic oil in the mold opening direction is made substantially equal to the moving speed of the movable platen 2. The impact on the movable platen 2 and the like is suppressed even at the time of shifting to speed control.

In the first half of the speed control by the servo valve 8, the open control is performed by the open control unit 30 in the same manner as at the time of the mold clamping described above (shown as an open control area O in FIG. 4). Then, the process is shifted to speed control by closed control (shown as a closed control area C in FIG. 4), and further, position control is performed under the closed control, and the movable platen 2 is stopped at a predetermined position. .

Even during such a mold opening operation, the opening control is performed in the first half of the speed control by the servo valve 8, and after the pressure fluctuation of the working oil supplied to the mold clamping cylinder 5 is stabilized. The control is shifted to the closed control. Unstable movement of the hydraulic oil generated when the communication between the hydraulic chambers 5a and 5b of the mold closing cylinder 5 is interrupted by the bypass valve 9 is also caused by the hydraulic oil being transferred from the tank 10 to the servo valve 8 via the check valve 11. By being pumped to the P port, it is stabilized early. Therefore,
The impact when shifting from open control to closed control is sufficiently mitigated.

On the other hand, after the speed control is completed, the movable platen 2 is subjected to position control under closed control based on the position information from the position detector 17 and the position command signal. 2 is stopped at the correct position.

As a result, for example, the positioning with respect to another device such as a molded product take-out machine is reliably performed.

As described above, according to the present embodiment, the change in the moving speed at the switching point between the open control and the closed control when the movable platen 2 moves is suppressed, and the movement of the movable platen 2 when the mold is opened and closed is smooth. In addition, the unstable movement of the hydraulic oil due to the operation of the bypass valve 9 is stabilized at an early stage, and the impact on the movable platen 2 and other components is suppressed.

Further, when the mold is opened, the stop position of the movable platen 2 is controlled with high precision by performing position control in the final stage by closed control using a servo valve.

The shapes, dimensions, and the like of each component shown in the above embodiment are merely examples, and can be variously changed based on the type of molding machine to be applied, design requirements, and the like.

[0042]

As described above, the method for controlling the opening and closing of a molding machine according to the present invention comprises a molding cylinder having a mold clamping cylinder for clamping a mold and an auxiliary cylinder for opening and closing the mold. A mold opening / closing control method for a machine, wherein a mold moving speed is detected during a mold opening / closing process by open control of the auxiliary cylinder, and a valve opening of a servo valve attached to the mold clamping cylinder is determined by the metal mold. While adjusting according to the moving speed of the mold, supply of hydraulic oil to this servo valve is stopped, and when the mold is moved to near the end of the mold opening / closing process, the servo valve is stopped. While supplying hydraulic oil, the first half of the speed control by the servo valve is performed by open control, and then the speed control by the servo valve is performed by using the speed information of the mold as a feedback signal. Characterized in that the closed controlled by Jitarusabo, excellent effects as follows.

By adjusting the opening of the servo valve in accordance with the speed of the mold being moved by the auxiliary cylinder, the operation of moving the mold by the auxiliary cylinder and the operation of moving the mold by the mold clamping cylinder At the time of switching, the amount of hydraulic oil corresponding to the current mold speed can be immediately supplied to the mold clamping cylinder, whereby the change in the mold speed at the time of switching from the open control to the closed control can be achieved. And the impact on the mold or other constituent members when opening and closing the mold can be reduced.

In addition, since the control of the mold stop position of the mold clamping and the mold opening is performed by the closed control based on the position information of the mold, the control of the mold stop position in each can be performed with high accuracy. The positional relationship between the stationary mold and the movable mold when the movable mold is stopped, and the positional relationship between the mold and another device such as a product removal device can be controlled with high accuracy.

[Brief description of the drawings]

FIG. 1 is a timing chart of a mold closing operation in a conventional molding machine.

FIG. 2 is a schematic diagram showing an example of an apparatus for carrying out the present invention.

FIG. 3 is a timing chart of a mold closing operation for explaining one embodiment of the present invention.

FIG. 4 is a timing chart of a mold opening operation for explaining one embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 mold clamping device 2 movable plate (mold) 5 mold clamping cylinder 7 auxiliary cylinder 8 servo valve 11 check valve 12 mold on-off valve 13 digital servo controller 17 position detector

Claims (1)

(57) [Claims] 1. A method for controlling opening and closing of a mold in a molding machine comprising a mold clamping cylinder for clamping a mold and an auxiliary cylinder for opening and closing the mold, wherein the mold is opened and closed by open control of the auxiliary cylinder. During the process, while detecting the moving speed of the mold, the valve opening degree of the servo valve attached to the mold clamping cylinder is adjusted according to the moving speed of the mold, and the operation of the servo valve is performed. Oil supply is stopped, and when the mold is moved to near the end of the mold opening / closing process, hydraulic oil is supplied to the servo valve, and the first half of speed control by the servo valve is performed by open control. Performing a closed control by a digital servo on the speed control by the servo valve, using the speed information of the mold as a feedback signal. Mold opening and closing control method.