JPS6222346Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improvement of the hydraulic circuit of a mold clamping cylinder in an injection molding machine.

Conventionally, in this type of hydraulic circuit, as shown in FIG. In addition, a safety door switching valve 14 was connected to the pilot pipe line on the mold clamping side and used as a dual electric and hydraulic safety circuit, but in this circuit, a solenoid switching valve 12 and a master valve 13
There was a drawback that the responsiveness was poor due to the overlapping of the two, and it took some time for the mold clamping cylinder to stop after switching the safety door switching valve 14 due to the operation of the safety door.

In addition, in order to improve responsiveness, the master valve 13 is omitted and the safety door switching valve 1 is connected directly to the mold clamping line of the solenoid switching valve 12, as shown in FIG.
4 is connected, and this circuit also has dual safety of hydraulic pressure (safety door valve) and electricity (solenoid switching valve), but in this circuit, the safety door switching valve 14 is always connected during mold opening/closing operation. Oil began to flow, and since it was not possible to flow a large amount of oil, it was not possible to open and close the mold at high speed, and currently the discharge rate is 50/min.
Can only be used on small aircraft.

In order to eliminate these drawbacks, the present invention eliminates the above drawbacks by simply adding one direct-acting solenoid switching valve to the embodiment shown in FIG. The present invention provides a hydraulic circuit for a mold clamping cylinder in an injection molding machine that improves the responsiveness of door operation.

The embodiment of the present invention will be explained with reference to FIG.
Reference numeral 1 designates a mold clamping cylinder, a safety door switching valve 3 is connected to the head side pipe 2, and pressure oil from a pump P is passed through the solenoid switching valve 4 and the safety door switching valve 3 to the head of the mold clamping cylinder 1. It is designed to be sent to the side. 5 is another solenoid switching valve connected to the rod side pipe 6 of the mold clamping cylinder 1, and is connected between the safety door switching valve 3 in the head side pipe 2 and the mold clamping cylinder 1 via a short circuit pipe 7. It's connected.

To explain the operation of the embodiment configured as described above, first, the safety door switching valve 3 is switched to the left of the illustrated position by closing the safety door valve (not shown), and then the solenoid switching valve The solenoid 4a of No. 4 is energized and switched to the right from the position shown in the figure, and pressurized oil from the pump P is sent to the mold clamping cylinder 1 to perform mold clamping. Also, at this time, the solenoid 5a of the solenoid switching valve 5 is energized to switch the solenoid switching valve 5 to the left from the illustrated position, and the oil in the rod side pipe 6 of the mold clamping cylinder 1 is transferred to the head via the short-circuit pipe 7. High-speed mold clamping is performed by merging the oil in the side pipe 2. At this time, since the pressure oil on both sides of the piston of the mold clamping cylinder 1 is balanced, the output of the mold clamping cylinder 1 is the product of the cross-sectional area of the piston rod and the hydraulic pressure, which is small, so the molds are brought into contact with a low output. Check for foreign objects between the molds. Thereafter, the solenoid switching valve 5 is set to the neutral position to cut off the flow of oil on the rod side, and main mold clamping is performed with a high output due to the product of the total piston area of the mold clamping cylinder 1 and the oil pressure.

Next, in the mold opening operation, when the safety door is closed (automatic operation), the solenoid 4b of the solenoid switching valve 4 and the solenoid 5b of the solenoid switching valve 5 are energized, and these solenoid switching valves 4,
5 to the left or right of the illustrated position, respectively, and open both valves 4 and 5 to the tank at the same time to perform high-speed mold opening. Furthermore, when the safety door is open (semi-automatic or manual operation), the oil on the head side is released into the tank via the safety door switching valve 3 and the solenoid switching valve 5, allowing high-speed mold opening.

As mentioned above, the present invention has a hydraulic circuit in which pressurized oil from a pump is sent to the mold clamping cylinder 1 through the solenoid switching valve 4 to perform mold clamping.
A safety door switching valve 3 is connected to the head side pipe line 2 of the mold clamping cylinder 1, and another solenoid switching valve 5 is connected to the rod side pipe line 6 of the mold clamping cylinder 1.
This is related to the hydraulic circuit of the mold clamping cylinder in an injection molding machine in which the solenoid switching valve 5 is connected to the head side pipe 2 via the short-circuit pipe 7. High-speed mold clamping is performed by merging the oil in the rod side pipes, and when the mold is opened, a large amount of oil generated due to the rod difference is transferred to the two solenoid switching valves 4 and 5, or the safety door switching valve 3 and the solenoid switching valve 5. At the same time, a large amount of oil can be released into the tank to perform high-speed mold opening through fully automatic, semi-automatic and manual operation. Moreover, electricity
It has a double hydraulic safety circuit and uses only a direct-acting solenoid switching valve, so the response is quick.Furthermore, a differential pressure circuit with a short-circuit pipe is used, so the low output allows temporary mold clamping of the mold. It has the advantage of increasing the effect of protecting the mold by performing the following steps.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention in comparison with a conventional embodiment; FIGS. 1 and 2 are circuit diagrams of the conventional embodiment, and FIG. 3 is a circuit diagram of the present invention. 1...Mold clamping cylinder, 2...Head side conduit,
3... Safety door switching valve, 4, 5... Solenoid switching valve, 6... Rod side pipe line, 7... Short circuit pipe line.

Claims (1)

[Scope of utility model registration request] In a hydraulic circuit that performs mold clamping by sending pressure oil from a pump to a mold clamping cylinder 1 via a solenoid switching valve 4, a safety door switching valve 3 is connected to a head side conduit 2 of the mold clamping cylinder 1. At the same time, another solenoid switching valve 5 is connected to the rod side pipe 6 of the mold clamping cylinder 1, and the solenoid switching valve 5 is connected to the head side pipe 2 via a short circuit pipe 7. Hydraulic circuit of mold clamping cylinder in molding machine.