JPH08207105A - Mold clamping device of injection molding machine - Google Patents

Abstract

PURPOSE: To safely stop a movable plate without using an accumulator being an emergency power source at the time of power failure by converting at least one of the opening and closing valves provided to the circuits communicating with the oil chambers of a plurality of cylinders from the oil pressure source in an oil pressure circuit from an 'open' state to a 'close' state at the time of power failure. CONSTITUTION: One terminal of a pilot circuit 25 is selectively allowed to communicate with an oil pressure source 9 and an oil tank 22 through a logic valve opening and closing controlling solenoid changeover valve 11 and the other terminal thereof is allowed to communicate with logic valves 12, 16 so as to open and close the circuit by the changeover of movable plate stopping solenoid changeover valves 20, 21 being circuit opening and closing valves and also allowed to communicate with logic valves 14, 18 so as to open and close the circuit by the changeover of movable plate stopping solenoid changeover valves 33, 34. If the solenoid changeover valves 20, 21, 33, 34 become an unexcited state by power failure, the logic valves 12, 14, 16, 18 become a 'close' state and, since the entrance and exit of pressure oil to the oil chambers 61a, 62a, 71a, 72a of respective cylinders is stopped, the movement of a movable plate is stopped.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold clamping device for an injection molding machine, which stops a movable plate moving at a high speed during a power failure.

[0002]

2. Description of the Related Art As shown in FIGS. 2 and 3, this type of mold clamping device includes a fixed plate 1, a plurality of parallel tie bars 3 and 4 having one end fixed to a movable plate 2, and a middle portion of each tie bar 3 and 4. The piston 5 provided at the position is slidably fitted to the inner diameter surface of the piston 5 and is integrally provided on the fixed plate 1.
A plurality of different C cylinders 6 and O cylinders 7 that mount the movable platen 2 together with the tie bars 3 and 4 such that the movable platen 2 can move forward and backward, and move the movable platen 2 at a high speed by a differential circuit. A mold clamping device of an injection molding machine having a hydraulic circuit 8 capable of selectively supplying pressure oil to the oil chambers of the C cylinder 6 and the O cylinder 7 is well known in the art. A hydraulic circuit as shown in FIG. 4 is provided.

In such a mold clamping device, when the movable platen 2 is moving at a high speed and the pump is stopped due to a power failure or the like, the movable platen 2 moves due to inertia and damages the mold and the like. There was a drawback that it would end up. For this reason, it has been customary to use an accumulator in the hydraulic circuit for controlling the mold clamping device as an emergency power source for stopping the movement of the movable platen 2 in the event of a power failure or failure of the hydraulic device.

The hydraulic circuit of this type of conventional apparatus will be described with reference to FIG. 4, in which the mold clamping C cylinders 61 and 62 and the mold opening O cylinders 71 and 72 are integrally fixed to each other, and the mold clamping, The mold-opening cylinders are arranged next to each other and of different types. The C cylinders 61 and 62 and the O cylinders 71 and 72 are pistons 5 having rods of tie bars 3 and 4 on their inner diameter surfaces.
Is slidably fitted.

The tie bars 3 and 4 are parallel to each other,
One end is fixed to a movable plate (not shown), and the other end penetrates the oil chambers of the C cylinders 61 and 62 and the O cylinders 71 and 72 to reach the outside. The tie bars 3 and 4 are each provided with the piston 5 in the middle thereof, and one end side and the other end side have different diameters with the piston 5 as a boundary.

A circuit 23 is connected to the mold clamping oil chambers 61a and 62a of the mold clamping C cylinders 61 and 62 through logic valves 12 and 14, respectively. The mold opening oil chamber 61b of the C cylinder 61 is connected to the circuit 23 via the logic valve 12, and a circuit 27 is provided between the oil chamber 61a and the oil chamber 61a to form a differential circuit. Further, the mold opening oil chamber 62b of the C cylinder 62 is connected to the circuit 23 through the logic valve 14, and a circuit 28 is provided between the oil chamber 62a and the oil chamber 62a to form a differential circuit.

On the other hand, a circuit 24 is connected to the mold opening oil chambers 71b and 72b of the mold opening O cylinders 71 and 72, respectively. The circuit 24 is connected to the mold clamping oil chamber 71a of the O cylinder 71 through the logic valve 16 and the oil chamber 7a.
A circuit 29 forming a differential circuit is provided between the circuit 29 and 1b. A circuit 24 is connected to the mold clamping oil chamber 72a of the O cylinder 72 through the logic valve 18, and a circuit 30 that forms a differential circuit with the oil chamber 72b is provided.

One end of the circuit 23 is selectively connected to the hydraulic power source 9 and the oil tank 22 via the electromagnetic switching valve 10.
The other end is connected to the mold clamping oil chambers 61a and 62a of the C cylinders 61 and 62 through the logic valves 12 and 14 as described above, and the O cylinders 71 and 72 are connected to the control logic valves 17 and 19 respectively. They are connected to the logic valves 16 and 18, respectively.

Further, the circuit 24 has one end which is the electromagnetic switching valve 1
0 is selectively connected to the oil pressure source 9 and the oil tank 22, and the other end is connected to the mold opening oil chambers 71b and 72b of the O cylinders 71 and 72 as described above, and the mold clamping C cylinder is used. Logic valve 1 for controlling 61 and 62
3 and 15 through the logic valves 16 and 1 respectively
Connected to 8.

The logic valves 12 and 16 are controlled to open and close their circuits by switching the electromagnetic switching valves 20 and 21 for stopping the movable plate, respectively. When the electromagnetic switching valves 20 and 21 are excited, the electromagnetic valves for controlling the opening and closing of the logic valves are controlled. By switching the switching valve 11, the switching circuit 11 communicates with the pilot circuit 25 that communicates with the hydraulic pressure source 9 and the oil tank 22, and the pilot circuit 25 causes the hydraulic pressure source 9 to communicate.
When the pilot valves 25 communicate with the oil tank 22, the logic valves 12 and 16 respectively open their circuits when they communicate with the oil tank 22. When the electromagnetic switching valves 20 and 21 are de-excited, the pressure oils from the accumulators 31 and 32 act on the logic valves 12 and 16, respectively.
2 and 16 are in the "closed" state. The logic valves 14 and 18 are in communication with the pilot circuit 25,
As with the logic valves 12 and 16 described above, by switching the solenoid control valve 11 for opening / closing control, the hydraulic pressure source 9
It also communicates with the oil tank 22.

The logic valves 13, 15, 17 and 19 are connected to a pilot circuit 26 which is connected to the hydraulic power source 9 and the oil tank 22 by switching the logic valve opening / closing control electromagnetic switching valve 11. Therefore, when the logic valve opening / closing control electromagnetic switching valve 11 is set to the b position, the pressure oil from the hydraulic pressure source 9 is guided to the pilot circuit 26, and the logic valves 13 and 1 are connected.
5, 17, and 19 are in the "closed" state. Further, at that time, since the circuit 25 is connected to the oil tank 22, the logic valves 14 and 18 are in the “open” state, and the logic valves 12 and 1
6 is in the "open" state when the electromagnetic switching valves 20 and 21 are excited.

The electromagnetic switching valve 11 for logic valve opening / closing control is a
At the position, the pressure oil from the hydraulic pressure source 9 is introduced to the circuit 25,
Since the circuit 26 is connected to the oil tank 22, the logic valve 1
4 and 18 are in the "closed" state, and the logic valves 12 and 16 are also in the "closed" state when the electromagnetic switching valves 20 and 21 are excited.
It becomes a state.

The structure is as described above. Next, the operation thereof will be described. First, when the mold is clamped, the mold opening / closing control electromagnetic switching valve 10 is in the a position and the logic valve opening / closing control electromagnetic switching valve 11 is in the b position. At the position, the electromagnetic switching valves 20 and 21 are excited respectively, and the pressure oil from the hydraulic pressure source 9 is applied to the circuit 23.
When acting on the mold clamping C cylinders 61 and 62,
Pressure oil acts on the pilot circuit 26 of the logic valves 13, 15, 17 and 19 to cause the valves 13, 15, 17 and 1 to operate.
9 is in the "closed" state, and the pilot circuits 25 of the logic valves 12, 14, 16 and 18 are connected to the oil tank 22 via the electromagnetic switching valve 11 and are in the "open" state. The oil acts on the oil chamber 61a and the oil chamber 62a of the C cylinder 62 from the circuit 23.

On the other hand, the pressure oil in the oil chamber 61b is passed through the logic valve 12 by the formed differential circuit to the C cylinder 6
It joins the pressure oil from the oil source 9 acting on the first oil chamber 61a. Further, the pressure oil in the oil chamber 62b of the C cylinder 62 joins the pressure oil acting on the oil chamber 62a of the C cylinder 62 via the logic valve 14 by the differential circuit formed in the same manner. .

In the mold opening O cylinders 71 and 72, the pressure oil in the oil chambers 71b and 72b is pushed out as the movable platen 2 is moved by the C cylinders 61 and 62.
That is, when the pressure oil in the oil chamber 71b is pushed out, the oil chamber 71b
a becomes a negative pressure state, the pressure oil pushed out from the oil chamber 71b is sucked into the oil chamber 71a via the logic valve 16, and the surplus oil is passed through the circuit 23 and the electromagnetic switching valve 10 to the oil tank. Returned to 22.

Similarly, in the O cylinder 72, the oil chamber 72a is in a negative pressure state, and the pressure oil extruded from the oil chamber 72b is passed through the logic valve 18 to the oil chamber 7 of the O cylinder 72.
The excess oil is sucked into 2a and returned to the oil tank 22 via the circuit 23 and the electromagnetic switching valve 10. Therefore, the piston 5, that is, the movable platen 2 (not shown)
Is moved to the right side in the figure at high speed, and the mold is clamped.

When the mold clamping process is completed as described above, and the injection process subsequent to the mold clamping process is completed and the molded product formed in the mold is taken out, the electromagnetic switching valve 10 is activated when the mold opening process is started.
Is switched to the b position, and pressure oil acts on the pilot circuits 26 of the logic valves 13, 15, 17, and 19 to cause the valve 1 to operate.
3, 15, 17 and 19 are in the "closed" state, and the pilot circuits 25 of the logic valves 12 to 18 are connected to the oil tank 22 via the electromagnetic switching valve 11 and are in the "open" state. The pressure oil in the oil chamber 71 b of the O cylinder 71 and the oil chamber 72 of the O cylinder 72 are passed through the circuit 24.
acts on b.

As a result, the pressure oil in the oil chamber 71a pushes open the logic valve 16 by the formed differential circuit and joins the pressure oil acting on the oil chamber 71b of the O cylinder 71. Further, the pressure oil in the oil chamber 72a of the O cylinder 72 joins the pressure oil acting on the oil chamber 72b of the O cylinder 72 via the logic valve 18 by the differential circuit formed in the same manner. .

In the mold closing C cylinders 61 and 62, as the movable platen 2 is moved by the mold opening and closing O cylinders 71 and 72, the oil chambers 61b and 62b are in a negative pressure state, and the circuit 24 and the electromagnetic switching valve 10 are turned on. Through the oil tank 22
Is supposed to suck oil from. That is, when the pressure oil is sucked into the oil chamber 61b of the C cylinder 61, the pressure oil extruded from the oil chamber 61a joins the oil chamber 61b via the logic valve 12 by the formed differential circuit. , The excess oil is passed through the circuit 23 and the electromagnetic switching valve 10 to the oil tank 22.
To return to.

Similarly, in the C cylinder 62, the pressure oil extruded from the oil chamber 62a is formed by the differential circuit through the logic valve 14 to the oil chamber 62b of the C cylinder 62.
The excess oil is returned to the oil tank 22 through the circuit 23 and the electromagnetic switching valve 10 when being sucked into the oil tank 22. Therefore, the piston 5, that is, the movable platen 2 (not shown) is moved to the left side in the drawing at a high speed, and the mold opening is performed.

During the die opening / closing operation, when the supply of pressure oil from the hydraulic source is stopped due to a power failure or the like, the electromagnetic switching valve 20,
21 is non-excited, and the pressure oils stored in the accumulators 31 and 32 act on the logic valves 12 and 16 via the electromagnetic switching valves 20 and 21, respectively.
And 16 are in the “closed” state, the pressure oil does not flow into and out of the oil chambers 61a, 71a of the C cylinder 61 and the O cylinder 71, and the movable platen 2 stops its movement.

[0022]

By the way, an accumulator is required to stop the movable platen during movement as described above, which not only increases the installation space but also increases the cost, and further increases the high pressure. There was also a problem in gas handling and maintenance such as management. The object of the present invention is to eliminate the above-mentioned drawbacks, without using an accumulator as an emergency power source at the time of a power failure or a failure of a hydraulic system, the movable plate can be safely stopped, its installation space is small, and the cost is low. An object of the present invention is to provide a mold clamping device for an injection molding machine that does not have a maintenance problem.

[0023]

In order to achieve the above-mentioned object, the present invention provides a fixed plate for supporting a fixed mold, a movable plate for supporting a movable mold, and at least a fixed plate or a plurality of parallel plates fixed to the movable plate. A tie bar and a piston provided in the middle of each tie bar are slidably fitted to the inner diameter surface,
A plurality of different cylinders that are integrally provided on the fixed plate or the movable plate and that mount the movable plate so that it can move back and forth and that move the movable plate at a high speed by moving a part of the sliding stroke of the movable plate by a differential circuit; In a mold clamping device of an injection molding machine having a hydraulic circuit capable of selectively supplying pressure oil to the oil chamber, a circuit communicating from an oil pressure source provided in the oil pressure circuit to the oil chambers of a plurality of cylinders is provided. A mold clamping device for an injection molding machine is characterized in that at least one of the provided on-off valves is changed from an "open" state to a "closed" state in the event of a power failure to stop the movement of the movable plate.

[0024]

According to the present invention, there is no accumulator as an emergency power source at the time of power failure or failure of the hydraulic system, the installation space can be made small, and the movable plate can be stopped safely.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, one embodiment of the present invention will be described with reference to FIG. The present invention eliminates the accumulator from the conventional example,
One end of the pilot circuit 25 is selectively communicated with the hydraulic power source 9 and the oil tank 22 via the logic valve opening / closing control electromagnetic switching valve 11, and the other end is connected to the logic valves 12 and 16 which are circuit opening / closing valves. Solenoid switching valve 2 for stop
The circuit is opened and closed by switching 0 and 21 and the logic valves 14 and 18 are opened and closed by switching the electromagnetic switching valves 33 and 34 for stopping the movable plate. Since it does not exist, the description of its configuration and members will be omitted, and only its operation will be described.

First, during mold clamping, the electromagnetic switching valve 10 for mold opening / closing control is set to the a position, the electromagnetic switching valve 11 for logic valve opening / closing control is set to the b position, and the electromagnetic switching valves 20, 21, 33 and 34 for stopping the movable plate are excited. Then, when pressure oil from the hydraulic power source 9 is applied to the mold clamping C cylinders 61 and 62 via the circuit 23, the pilot circuits 25 of the logic valves 12, 14, 16 and 18 are operated via the electromagnetic switching valve 11. Oil tank 22
The hydraulic oil from the hydraulic source 9 acts on the oil chamber 61a of the C cylinder 61 and the oil chamber 62a of the C cylinder 62, and the oil chamber 6 of the C cylinder 61 is connected.
The pressure oil in 1b is the logic valve 1 by the formed differential circuit.
2 and joins the pressure oil from the oil source 9 acting on the oil chamber 61a. Further, the oil chamber 62b of the C cylinder 62
The pressure oil inside is also made to join with the pressure oil which acts on the oil chamber 62a of the C cylinder 62 via the logic valve 14 by the differential circuit formed similarly.

On the other hand, in the mold opening O cylinders 71 and 72, as the movable platen 2 is moved by the C cylinders 61 and 62, the pressure oil in the oil chambers 71b and 72b is pushed out.
That is, when the pressure oil in the oil chambers 71b and 72b is extruded, the oil chambers 71b and 72b are brought into a negative pressure state, and the pressure oil extruded from the oil chambers 71b and 72b is supplied to the logic valves 16 and 18, respectively. The excess oil is sucked into the oil chambers 71a, 72a via the circuit 23 and the excess oil is supplied to the circuit 23 and the electromagnetic switching valve 10.
It is returned to the oil tank 22 via. Therefore the piston 5,
That is, the movable platen 2 (not shown) is moved to the right side in the drawing at a high speed, and the mold is clamped.

In the meantime, the electromagnetic switching valves 20, 2 due to a power failure or the like.
If 1, 33 and 34 are not excited, the logic valve 12,
Since 14, 16 and 18 are in the "closed" state and no pressure oil flows in and out of the oil chambers 61a, 62a, 71a and 72a of each cylinder, the movable platen 2 stops its movement.

Similarly, when the mold is opened, the mold is opened as described in the conventional example, and the electromagnetic switching valves 20, 2 are opened due to a power failure or the like.
If 1, 33 and 34 are not excited, the logic valve 12,
14, 16 and 18 are in the "closed" state, and the movable platen 2 stops its movement.

In the above description, an example in which a plurality of electromagnetic switching valves for stopping the movable platen are provided respectively for the mold clamping cylinder and the mold opening has been described, but the invention is not limited to this, and the movable platen stop is provided for at least one cylinder. It is possible to stop the movable plate by providing an electromagnetic switching valve for use.

[0031]

As described above, the present invention eliminates the use of an accumulator as a power source for stopping the movable platen that is moving during a power failure, thus reducing the installation space of the entire apparatus and reducing the cost. Not only has it improved, but it has also been improved in terms of maintenance such as handling high-pressure gas.

[Brief description of drawings]

FIG. 1 is a hydraulic circuit diagram for controlling a mold clamping device according to the present invention.

FIG. 2 is a diagram illustrating a conventional mold clamping device.

FIG. 3 is a sectional view taken along line AA of FIG. 2;

FIG. 4 is a hydraulic circuit diagram for controlling a conventional mold clamping device.

[Explanation of symbols]

 1 Fixed plate 2 Movable plate 3 Tie bar 4 Tie bar 5 Piston 6 Cylinder for mold closing 7 Cylinder for mold closing 9 Cylinder for mold closing 9 Hydraulic source 10 Solenoid switching valve for mold opening / closing control 11 Logic valve Open / close control electromagnetic switching valve 12 Logic valve 13 Logic valve 14 Logic Valve 15 Logic valve 16 Logic valve 17 Logic valve 18 Logic valve 19 Logic valve 20 Moving plate stop electromagnetic switching valve 21 Moving plate stop electromagnetic switching valve 22 Oil tank 23 Circuit 24 circuit 25 Pilot circuit 26 Pilot circuit 27 circuit 28 Circuit 29 Circuit 30 Circuit 31 Accumulator 32 Accumulator 33 Electromagnetic switching valve for moving plate stop 34 Electromagnetic switching valve for moving plate stop 61 C-cylinder for mold clamping 62 C-cylinder for mold clamping 71 O-cylinder for mold opening 72 O-linda for mold opening

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Satoshi Okutani 2068-3 Ooka, Numazu City, Shizuoka Prefecture Numazu Works, Toshiba Machine Co., Ltd.

Claims (1)

[Claims] 1. A fixed plate for supporting a fixed die, a movable plate for supporting a movable die, at least a plurality of parallel tie bars fixed to the fixed plate or the movable plate, and a piston provided at an intermediate position of each tie bar. While being slidably fitted to the inner diameter surface, integrally provided on the fixed plate or the movable plate,
The movable plate is mounted so that it can move back and forth, and a plurality of different cylinders that move a part of the sliding stroke of the movable plate at high speed by a differential circuit, and pressure oil can be selectively supplied to the oil chamber of each cylinder. In a mold clamping device of an injection molding machine having a hydraulic circuit, at least one of the on-off valves provided in the circuit communicating with the oil chamber of each of the plurality of cylinders from the hydraulic source provided in the hydraulic circuit at the time of power failure A mold clamping device for an injection molding machine, characterized in that the movable platen is stopped from moving from the "open" state to the "closed" state.