JPH0410410B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a molding machine that allows pressing force to be set extremely accurately.

Conventionally, there is a known type in which a pressure receiving member is provided with a pressure member, the pressure member is pressed against the lower surface of the pressure receiving member by a hydraulic piston cylinder, and a formwork containing a molding material such as rubber is press-formed between these two members. It will be done. However, this pressurizing force is generally set by converting the pressure displayed on a pressure gauge interposed in the oil passage of the hydraulic piston cylinder. However, the value displayed on the pressure gauge includes the weight of the movable platen, the sliding resistance between the packing interposed in the piston cylinder and the piston, etc., so it is impossible to know the exact pressing force. is the current situation.

Therefore, this product can be used to detect the appropriate load when testing the appropriate load of new materials or products, or to set the minimum required pressure when molding with a core material that is easily damaged. becomes difficult.

In view of the current situation, it is an object of the present invention to provide a molding machine that can easily set an accurate pressurizing force. In a molding machine that pressure-forms a molding material such as rubber between these two members by pressing it against the bottom surface, the pressure receiving member is suspended from the machine frame via a spring, and the pressure receiving member is placed opposite to the top surface of the pressure receiving member. A load cell is provided that can set a set load, an upper limit load, and a lower limit load and generates a command signal when each load value is detected, and the upper and lower chambers of the hydraulic piston cylinder are connected to a hydraulic source via a four-way electromagnetic switching valve. At the same time, a return passage for returning hydraulic pressure to the tank is connected between the lower chamber and the four-way solenoid switching valve via an electromagnetic relief valve, and when the lift switch is turned on, the four-way solenoid switching valve is connected downward from the hydraulic source. The four-way electromagnetic switching valve, which has been switched to the switching position, is switched to the neutral position by the command signal of the load cell for detecting the set load, and is normally kept in the closed position. The relief valve that is maintained is switched to the open position by the command signal from the load cell for detecting the upper limit load, and the four-way electromagnetic switching valve, which was switched to the neutral position by the command signal from the load cell for detecting the lower limit load, is switched from the hydraulic source. It is configured to switch to a switching position where hydraulic pressure is supplied to the lower chamber.

An example of implementing the present invention will be explained with reference to the attached drawings.

In the drawing, 1 is a machine frame, 2 and 3 are a pressure member and a pressure receiving member supported by this, 4 is a hydraulic piston cylinder for driving the pressure member 2, and 5 and 5 are opposing sides of both members 2 and 3. A heating plate provided on the surface is shown, and the hydraulic piston cylinder 4 moves the pressure member 2 to the pressure receiving member 3.
There is no particular difference from the conventional method in that the molding material is press-molded or press-vulcanized by pressing the molding material into the mold a interposed between the two members 2 and 3.

In such a molding machine, the pressure receiving member 3 is supported by a plurality of support rods 6 that vertically penetrate the top plate 1a of the machine frame 1.
The hydraulic chambers 4a are suspended by a spring 7 interposed between the enlarged portion 6a at the upper end and the top plate 1a so as to offset their own weight, and are formed above and below the piston 8 inserted into the hydraulic piston cylinder 4. 4b is connected to a hydraulic power source 10 via a four-way electromagnetic switching valve 9, and an electromagnetic on-off valve 14 and a bypass passage 13 that bypasses this are interposed in an oil passage 11 connecting the four-way electromagnetic switching valve 9 and the lower hydraulic chamber 4b. , hydraulic power source 10
A throttle valve 12 is provided to throttle the amount of oil supplied to the lower chamber 4b side, and the oil passage 11 is connected to the throttle valve 12.
Also, on the chamber 4b side below the electromagnetic on-off valve 14,
A return passage 18 for returning hydraulic pressure is connected to a tank 17 connected to a hydraulic pressure source 10 via an electromagnetic relief valve 16.

Reference numeral 19 indicates a throttle valve interposed in the return passage 18. Three load cells 20a, 20b, and 20c are provided on the lower surface of the top plate 1a, which can set a set load, its upper limit load, and its lower limit load, and generate respective command signals when each load value is detected.

Next, the operation of this device will be explained using the sequence circuit shown in FIG. When closing the lift switch SW ₁ , the solenoid D of the four-way electromagnetic switching valve 9 is energized and the four-way electromagnetic switching valve 9 is connected to the piston cylinder 4.
The lower chamber 4b of the piston cylinder 4 is switched to a switching position where hydraulic pressure is supplied from the hydraulic source 10 to the lower chamber 4b of the piston cylinder 4. Therefore, the pressure member 2 is raised by the piston cylinder 4, and both members 2,
3. Push up the formwork a until it is pressed. Then, the pressure in the hydraulic circuit increases, closing the pressure switch SP interposed therein, and as a result, the solenoid A of the electromagnetic switching valve 14 is energized, and its excitation causes the electromagnetic switching valve 14 to close. Switch to
Therefore, the lower chamber 4b is supplied with a very small amount of hydraulic pressure via the throttle valve 12 interposed in the bypass passage 13. When the oil pressure exceeds the lower limit load value and further exceeds the set load value, the load cell 20
A and 20c generate respective command signals, and the signals close switches SW ₄ and then SW ₂ , and energize relays R ₃ and then R ₂ interposed therewith. For this reason, the b contacts r ₃ and r ₂ -1 are interposed in the solenoid D.
As a result, the solenoid D is deenergized and the four-way electromagnetic switching valve 9 automatically returns to the neutral position.
Therefore, the pressure increase in the lower chamber 4b is stopped. When the pressure in the hydraulic circuit reaches the upper limit load value due to changes in oil temperature, expansion or contraction due to temperature changes in the hot platen, or changes in the state of the molded product, a command signal is sent to the load cell 20b for detecting the upper limit load. and closes the switch SW ₃ to energize the relay R ₁ and close the contact r intervening in the solenoid B of the relief valve 16.
6 to the valve open position. Therefore, a part of the oil pressure in the lower chamber 4b escapes to the tank 17 side via the throttle valve 19, and the oil pressure decreases.

When the oil pressure drops to the set load value, switch SW ₂ is opened to prevent the command signal from being sent to the load cell 20a for detecting the set load, and solenoid B of the relief valve 16 is activated.
Relief valve 1 intervenes to open its a contact r ₂ -2
6 returns to the closed position.

Also, if the oil pressure in the lower chamber 4b decreases for some reason and becomes lower than the lower limit load value, the load cell 20
When a loses the command signal, switch SW ₄ opens, relay R ₃ is demagnetized, and b contact r ₃ that intervenes in solenoid D of four-way electromagnetic switching valve 9 and solenoid A of electromagnetic switching valve 14 is closed. The four-way electromagnetic switching valve 9 is then switched to the switching position for supplying hydraulic pressure from the hydraulic source 10 to the lower chamber 4b, and the solenoid A of the electromagnetic switching valve 14 is energized to switch the solenoid A to the closed position. Therefore, a small amount of hydraulic pressure is supplied to the lower chamber 4b via the throttle valve 12.

This operation is repeated to keep the pressure in the lower chamber 4a constant. After completing the pressurization work, turn the down switch.
By closing SW ₅ , the solenoid C of the four-way electromagnetic switching valve 9 is energized, and hydraulic pressure is applied to the upper chamber 4a to switch the pressure member 2 to the switching position where hydraulic pressure is supplied from the hydraulic source 10 to the upper chamber 4a. lower it. Sho R ₆
indicates a relay interposed in parallel with the solenoid D, whose relay contact _r6 is interposed in parallel with switch _SW1 to self-hold the solenoid D until the pressurized load exceeds the set load value to the upper limit load value. .

Further, in FIG. 2 _{, R4} indicates a relay that intervenes in parallel with solenoid B, and the a contact _r4 of this relay _R4 intervenes in parallel with the contact _r1 to maintain the solenoid B in an energized state. In addition, _R5 indicates a relay inserted in parallel with the solenoid C, and its b contact _R5 intervenes with the solenoid D, so that when the solenoid C is operated, the solenoid D is not operated.

LS indicates a limit switch that opens when the pressure member 2, which is intervened by the solenoid C, is lowered.

In this way, according to the present invention, by suspending the pressure receiving member from the machine frame via the spring, the own weight of the pressure receiving member is offset, and when the pressure forming is performed by the pressure member, the own weight of the pressure receiving member is In addition to eliminating changes in oil pressure through the member, it is possible to set the set load, upper limit load, and lower limit load by facing the top surface of the pressure receiving member, and generates a command signal when each load value is detected. A load cell is provided, and the upper and lower chambers of the piston of the hydraulic piston cylinder are connected to a hydraulic power source via a four-way electromagnetic switching valve, and between the lower chamber and the four-way electromagnetic switching valve, a load cell is connected from the hydraulic source to the lower chamber side. A throttle valve that throttles the amount of oil to be supplied, and an electromagnetic on-off valve interposed in parallel with the throttle valve, and a tank that is connected to a hydraulic source via an electromagnetic relief valve between the throttle valve, the electromagnetic on-off valve, and a lower chamber. A return passage is connected to restore the hydraulic pressure, and the four-way electromagnetic switching valve is switched to the neutral position by the command signal from the load cell for detecting the set load, and the relief valve is switched to the closed position by the command signal from the load cell for detecting the upper limit load. Furthermore, in response to a command signal from the load cell for detecting the lower limit load, the four-way electromagnetic switching valve, which had been switched to the neutral position, is switched to the switching position where hydraulic pressure is supplied from the hydraulic source to the lower chamber, so that the pressurizing force can be reduced. This has the effect of allowing extremely accurate settings.

[Brief explanation of drawings]

In the drawings, FIG. 1 is a system diagram of one example of implementing the present invention, and FIG. 2 is a sequence circuit diagram. 2... Pressure member, 3... Pressure receiving member, 4... Hydraulic piston cylinder, 4a, 4b... Hydraulic chamber, 9...
...four-way electromagnetic switching valve, 10...hydraulic source, 14...electromagnetic switching valve, 17...tank, 18...return passage, 20a, 20b, 20c...load cell.

Claims (1)

[Claims] 1. In a molding machine that is equipped with a pressure receiving member and a pressure member, the pressure member is pressed against the lower surface of the pressure receiving member by a hydraulic piston cylinder, and a molding material such as rubber is formed between these two members under pressure. is suspended from the machine frame via a spring, and is placed opposite to the upper surface of the pressure receiving member to provide a load cell that can set a set load, an upper limit load, and a lower limit load, and generates a respective command signal when each load value is detected. Further, the upper and lower chambers of the hydraulic piston cylinder are connected to a hydraulic power source via a four-way electromagnetic switching valve, and the hydraulic pressure is returned to the tank via an electromagnetic relief valve between the lower chamber and the four-way electromagnetic switching valve. When the return passage is connected and the lift switch is turned on, the four-way solenoid switching valve is switched to the switching position where hydraulic pressure is supplied from the hydraulic source to the lower chamber. The command signal from the load cell for detecting the set load switches the relief valve to the neutral position, and the relief valve, which is normally kept in the closed position, is switched to the open position by the command signal from the load cell for detecting the upper limit load. A molding machine configured to switch a four-way electromagnetic switching valve, which has been switched to a neutral position, to a switching position where hydraulic pressure is supplied from a hydraulic source to a lower chamber in response to a command signal from a hydraulic pressure source.