JPH11129037A - Safety circuit of press die cushion - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the safety circuit of the press die cushion to prevent an inadvertent lifting of a pad. SOLUTION: The circuit comprises; an air operate type No.1 master valve 6 to be controlled by a pressure in a cushion cylinder 2, a single SOL type solenoid valve 19 to forcefully open the No.1 master valve 6 by a factory air when the die cushion is used, single SOL type solenoid valves 3, 14 to switch and control an air supplying valve 10 and an exhaust valve 12, pilot operate type No.2 master valves 15, 16 having an inverse direction position, a single SOL type solenoid valve 17 to control a locking valve 18 which controls a locking cylinder 3, and spring return type No.3 master valves 25, 26 which actuates the switch control SOL type solenoid valves 13, 14 open at the time of air feeding position 131 , 141 and close at exhaust positions 132 , 142 .

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a safety circuit for a press die cushion for preventing a pad from being inadvertently raised.

[0002]

2. Description of the Related Art Conventionally, as this kind of safety circuit, for example, a circuit described in Japanese Patent Application Laid-Open No. HEI 8-19822 is known.

[0003] The safety circuit disclosed in the above publication is a press die cushion provided with a pad elastically supported by a cushion cylinder and a locking circuit for locking the pad.
An on-off valve that is mechanically turned on when the pad is near the lower limit position while using an L-type solenoid valve, a solenoid valve that is shut off when the power is turned on and communicates with the power off, and these on-off valves and solenoid valves The exhaust valve, which is switched to the exhaust side by the pilot pressure supplied via the, is connected to the air supply circuit of the cushion cylinder. Since the state of the solenoid valve is maintained at that position, the pad does not move up and down carelessly.

[0004]

However, in the above-mentioned conventional safety circuit, the position of the cam valve mounted on the bed is turned on and off by the cam plate mounted on the pad. When the contact part wears out, the cam valve does not turn on and off because of the structure of mechanically operating the cam plate by contacting the cam plate with the cam valve.In order to operate the safety circuit stably for a long period of time, There is a problem in that it is necessary to perform a proper wear check and an operation timing check, and it takes time and effort for maintenance management.

Further, since a large-diameter exhaust valve controlled by a cam valve is required between the cushion cylinder and the air tank in addition to the main exhaust valve, there is a problem that the apparatus becomes expensive. SUMMARY OF THE INVENTION The present invention has been made to solve such a conventional problem, and an object thereof is to provide a safety circuit for a press die cushion in which a pad does not move up and down against a worker's intention at a low cost with a simple configuration. It is assumed that.

[0006]

In order to achieve the above object, the present invention is directed to a press die cushion having a pad elastically supported by a cushion cylinder and a locking cylinder for locking the pad. A first air operated type master valve provided between an air tank for supplying air to the cushion cylinder and a factory air line and opened when the pressure in the cushion cylinder is high and closed when the pressure in the cushion cylinder is low; Switching control of a single SOL type solenoid valve forcibly opening the first master valve with factory air when using a cushion, and switching between an air supply valve and an exhaust valve provided in a pipe connecting between the cushion cylinder and the air tank SOL type solenoid valves, and a solenoid valve provided between these solenoid valves and the supply / exhaust valve. And a pilot operated type second master valve having a position opposite to that of the solenoid valve, and a pilot valve of the locking valve which is connected to the air cylinder circuit side of the locking valve for controlling the locking cylinder and is opened when the power is turned off. Is introduced between the solenoid valve and the second master valve, and the solenoid valve is provided between the solenoid valve and the second master valve, and is opened when the solenoid valves of both SOL types are in the air supply position. It is constituted by a third master valve of a spring return type that operates so as to be closed when in the exhaust position.

According to the above configuration, when the power is turned off due to a power failure or the like while the pad is locked near the lower limit position by the locking circuit, the single SOL type solenoid valve is opened and the pilot air of the locking valve is released by the single SOL. To the second master valve via a solenoid valve of the type and the open third master valve, the second master valve is switched to the exhaust side and the air in the cushion cylinder is exhausted through the exhaust valve. Even if the locking by the locking cylinder is released due to oil leakage or the like, the pad does not inadvertently rise, whereby the mold is pushed up by the pad and interferes with the work transfer device or the like stopped upward. Therefore, such damage can be prevented beforehand.

Further, even if a power failure or the like occurs when an operator intentionally switches the electromagnetic valve to the exhaust position to lower the pad while the pad is locked at the lower limit position, the power supply may be stopped. When the solenoid valve is switched to the exhaust position, the third master valve is closed, so that the air of the locking cylinder is not supplied to the second master valve. Since it does not rise, work safety can be improved.

Further, since the master valve is turned on and off by the pilot air, it requires no work such as position adjustment and a malfunction due to abrasion as compared with a conventional cam which mechanically turns the valve on and off. Because there is no need to worry about this, and because it can be configured with only a plurality of master valves and pilot lines, the equipment is simple and there is no need to provide a large-diameter exhaust valve separately from the main exhaust valve. it can.

[0010]

Embodiments of the present invention will be described in detail with reference to the drawings. In FIG. 1, reference numeral 1 denotes a pad constituting a die cushion device, 2 denotes a cushion cylinder formed by an air cylinder which elastically supports the pad 1 from below, and 3 denotes a locking cylinder formed by a hydraulic cylinder which locks the pad 1 near its lower limit. 5 is a factory airline, and the air of this factory airline 5 is a factory airline 5
Is supplied to an automatic pressure regulating circuit 7 via a pilot operated type first master valve 6 which opens and closes the valve.

The automatic pressure regulating circuit 7 comprises a factory air line 5
The automatic pressure regulating circuit 7 is connected in parallel with a manual pressure regulating circuit 8 so that the pressure can be manually regulated when the circuit 7 fails. The air regulated by the pressure circuits 7 and 8 is supplied to the air tank 9 and then supplied to the cushion cylinder 2 via the air supply valve 10 and the conduit 11, and is supplied to the conduit 11. Is connected to an exhaust valve 12 for discharging air from the cushion cylinder 2.

The pressure in the cushion cylinder 2 is
By the pilot pipeline 11a branched from the pipeline 11,
The first master valve 6 is supplied to the first master valve 6 as pilot air. When the pressure in the cushion cylinder 2 is high, the first master valve 6 is opened, and when the pressure is low, the first master valve 6 is closed. Between the factory air lines 5, a single SOL type solenoid valve 19 for forcibly opening the first master valve 6 by the factory air when the die cushion device is used is connected.

On the other hand, the air supply valve 10 and the exhaust valve 12 are constituted by pilot operated type switching valves which are switched by air pilot air.
Opening / closing control is performed by L-type solenoid valves 13 and 14, and a position opposite to the solenoid valves 13 and 14 is provided between the supply / exhaust valves 10 and 12 and the solenoid valves 13 and 14. The second master valves 15 and 16 are interposed.

The second master valves 15 and 16 are composed of double pilot operated type switching valves which are switched and controlled by pilot air supplied to both ends thereof. spring There is introduced, at the other end is opened when the solenoid valve 13, 14 is switched to the air supply position ₁₃ 1, 14 _1, which is closed when it is switched to the exhaust position ₁₃ 2, 14 ₂ Return type third master valve 2
Air is introduced from the locking circuit 20 through the solenoid valve 17 of a single SOL type which is closed when the power is turned on and is opened when the power is turned off.

The locking circuit 20 has a locking valve 18 connected to each of the locking cylinders 3 provided below the cushion cylinder 2. These locking valve 18 is turned on by the pilot air supplied through the electromagnetic valve 22 from the air tank 21, are turned off, while the upper chamber 3 ₁ and the lower chamber 3 ₂ locking cylinder 3 so as to be communicated with, interrupted ing.

The other air cylinder 18a of the locking valve 18 and the other ends of the second master valves 15 and 16 are connected via a solenoid valve 17 and third master valves 25 and 26, respectively. When the solenoid valve 17 is opened when 25 and 26 are open, the air cylinder 18a
The air inside is the second master valve 1 as pilot air.
It flows into the other end side of 5,16.

Next, the operation will be described. To operate the press, a power switch (not shown) is turned on.
If the pad 1 has been left for a long time in the upper limit position, the pad 1 has been lowered to the lower limit position due to air leakage. When air is supplied to the cushion cylinder 2 in this state, the pad 1 rises rapidly. Dangerous. However, in the present invention, when the air pressure in the cushion cylinder 2 is low,
The first provided between the factory air line 5 and the air tank 9
Since the master valve 6 is in the closed state, the air in the factory air line 5 is not supplied to the air tank 9 side, thereby preventing the pad 1 from being inadvertently raised.

Next, when using the die cushion device, the solenoid valve 19 is turned on. As a result, the air of the factory air line 5 is supplied to the first master valve 6 via the solenoid valve 19.
The first master valve 6 is forcibly opened, and the air in the factory air line 5 is adjusted to a specified pressure by the automatic pressure adjusting circuit 7 and then supplied to the air tank 9. Then, the pad 1 is supplied to the cushion cylinder 2 through the opened air supply valve 10 and the pipe line 11, and the pad 1 is raised to the upper limit position by the cushion pressure of the cushion cylinder 2.

Next, when press work is started in this state,
As the molding proceeds, the pad 1 is pushed down to reach the lower limit position, and then the slide (not shown) rises. However, after the pad 1 is temporarily locked near the lower limit position by the locking cylinder 3, the locking valve 18
Opening with a, for the oil of the upper chamber 3 ₁ flows into the lower chamber 3 ₂ side, raised to the upper limit position by the cushioning action of the cushion cylinder 2, to end the molding process.

Meanwhile third master valve 25 is opened and the solenoid valve 13, 14 is switched to the air supply position ₁₃ 1, 14 _1, operations to close and is switched to an exhaust position ₁₃ 2, 14 ₂ while, because the state in which the pad 1 is rocking (this time the solenoid valve 13, 14 by locking the cylinder 3 during press molding is in the air supply position ₁₃ 1, 14 _1, third master valve 25 and 26 open When the power is turned off due to a power failure or the like, the solenoid valve 17 connected between the second master valves 15, 16 and the locking valve 18 is not energized, and the solenoid valve 17 is exhausted by the action of the spring 17a. is switched from position 17 ₁ to the communicating position 17 _2, whereby the air cylinder 18 of the locking valve 18 Some of the air being supplied is supplied as pilot air through the third master valve 25 and 26 are connecting positions 17 ₂ and opening of the solenoid valve 17 to the second master valve 15 and 16.

As a result, the second master valves 15 and 16 which have been switched to the air supply side are switched to the exhaust side, the air supply valve 10 is closed, the exhaust valve 12 is opened, and the air in the cushion cylinder 2 is opened. Is exhausted from the exhaust valve 12 and the pad 1 remains stopped at the lower limit position. Therefore, even if the oil in the locking cylinder 3 leaks and the locking is released, the pad 1 does not rise, It is possible to prevent a problem that the mold collides with the work transfer device stopped above the mold and the two are damaged.

On the other hand in a state in which the pad 1 is locking the lower limit position by the locking cylinder 3, the operator in order to intentionally lower the pad 1, switch the solenoid valves 13 and 14 to the exhaust position 13 _2, 14 ₂ In this case, the third master valves 25 and 26 are shut off.

[0023] Thus the power failure occurs in this state, even I switching solenoid valve 17 to the communicating position 17 _2, the air in the air cylinder 18a of the locking valve 18, the third
Since the second master valves 15 and 16 are not supplied to the second master valves 15 and 16 after being shut off by the master valves 25 and 26, the second master valves 15 and 16 are not switched, whereby the pad 1 rises against the intention of the operator. Work safety can be improved.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a safety circuit of a press die cushion according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Pad 2 ... Cushion cylinder 3 ... Locking cylinder 5 ... Factory air line 6 ... First master valve 9 ... Air tank 10 ... Air supply valve 12 ... Exhaust valve 13, 14 ... Solenoid valve 15, 16 ... Second master valve 17 ... Solenoid valve 18 ... Locking valve 19 ... Solenoid valve 20 ... Locking circuit 25, 26 ... Third master valve

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Kazuo Kubo, 5th Yokaichi-cho, Komatsu-shi, Ishikawa Prefecture Inside the Komatsu Plant of Komatsu Ltd. (72) Katsuhiro Takano 5th, Yokaichi-cho, Komatsu-shi, Ishikawa Co., Ltd. Komatsu Plant, Komatsu Plant (72) Inventor Yusuke Uedera, 5 Yokaichi Town, Komatsu City, Ishikawa Prefecture Komatsu Plant, Komatsu Plant

Claims (1)

[Claims] 1. A press die cushion comprising a pad 1 elastically supported by a cushion cylinder 2 and a locking cylinder 3 for locking the pad 1.
An air operated type first master valve provided between an air tank 9 for supplying air to the cushion cylinder 2 and the factory air line 5 and opened when the pressure in the cushion cylinder 2 is high and closed when the pressure in the cushion cylinder 2 is low. 6
And a solenoid valve 19 of a single SOL type forcibly opening the first master valve 6 with factory air when using a die cushion, and a supply line provided in a pipe line 11 connecting the cushion cylinder 2 and the air tank 9. Solenoid valves 13 and 1 of both SOL type for switching and controlling the air valve 10 and the exhaust valve 12
4, the solenoid valves 13, 14 and the supply / exhaust valves 10, 1
2 and a pilot operated type second master valve 15, 16 having a position opposite to the solenoid valves 13, 14 and a locking valve 18 for controlling the locking cylinder 3 connected to the air cylinder circuit side. A solenoid valve 17 of a single SOL type, which is opened when the power is turned off and introduces pilot air of a locking valve 18 to the second master valves 15 and 16;
The two SOL type solenoid valves 13, 1 are provided between the solenoid valve 17 and the second master valves 15, 16, and are both SOL type solenoid valves 13, 1.
4 is opened when the air supply position 13 ₁ , 14 ₁ ,
Safety circuit of the press die cushion, characterized by comprising a third master valve 25 and of the spring-return type which is operable for closing when the exhaust position 13 _2, 14 _2.