JPS60131216A - Hydraulic driving mechanism for opening and closing mold for injection molding machine - Google Patents

Abstract

PURPOSE:To move a ram for an injection molding machine smoothly, and to improve the productivity of the injection molding machine by fittng an electromagnetic changeover valve smoothly moved immediately before a contact between the ram and a mold, etc. when the ram for the injection molding machine shifting at high speed is brought into contact with the mold, etc. CONSTITUTION:A ram 12 proceeds at high speed because compressed oil flows into a boosting cylinder 14 through a duct 21 and a boosting ram 13. Oil in an A chamber 15 in a mold clamping cylinder 11 is discharged into a tank 24 through a duct 18, a check valve 17, a duct 19, an A electromagnetic changeover valve 20 and a duct 23 because a relief valve 16 is closed at that time. The check valve 17 is closed and the pressure of oil in the A chamber 15 in the mold clamping cylinder 11 is elevated until the relief valve 16 is opened and the forward movement of the ram 12 is braked because a B electromagnetic changeover valve 29 is changed over to a position (a) by a limit switch immediately before the ram 12 is brought into contact with a mold. Accordingly, the ram 12 is brought smoothly into contact with the mold. The same applies to the case of the retreat of the ram.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical field to which the invention pertains] The present invention relates to a hydraulic drive mechanism used for opening and closing a mold of an injection molding machine.

Generally, when opening and closing the mold of an injection molding machine, a boost cylinder is used to advance the movable die plate tube fixed in front of the movable die at high speed, and when the movable die comes into contact with the fixed die fixed to the fixed die plate, pressurized oil is released. The boost cylinder was switched to the mold clamping cylinder to generate a powerful mold clamping force.

[゛Conventional technology゛]

When the main mold clamping ram moves forward, the movable mold is moving forward at high speed, so when it comes into contact with the fixed mold at its stroke limit, it generates an impact that can damage both molds. Immediately before contact with the mold, the pressure of the pressure oil supplied to the pist cylinder was lowered to reduce the amount of oil. Although this method was effective in preventing damage to both molds, it took time to raise the oil pressure again, lowering productivity. Similarly, when the ram retreats, the moving die plate suddenly stops at the stroke limit, which generates an impact that has an unfavorable effect on the injection molding machine. For this reason, the pressure of the supply pressure oil is lowered just before the stroke limit, which lowers productivity.

[Purpose of the invention]

The present invention eliminates these drawbacks, and its purpose is to:
When the ram is moving, the pressure of the supply pressure oil is not lowered just before the stroke limit, and when the ram is moving forward, both dies are brought into smooth contact, and then the pressure increases, and when the ram is retracting, the pressure is increased smoothly and in a short time. It is an object of the present invention to provide a hydraulic drive mechanism for opening and closing a mold of an injection molding machine, which increases productivity by stopping the machine.

[Key points of the invention]

The mold opening/closing hydraulic drive mechanism of the injection molding machine of the present invention includes an A electromagnetic switching valve that controls the forward and backward movement of the main ram moved by the boost ram, and an A electromagnetic switching valve that controls the forward and backward movement of the main ram that is moved by the boost ram. IJ-
7 valve, a pilot-operated check valve connected in parallel to the relief valve, and a B [i switching valve and It is characterized by consisting of.

[Embodiments of the invention]

The present invention will be explained below with reference to figures showing one embodiment. A movable die plate (not shown) is attached to the right side of the ram 120, which is slidably inserted in the mold clamping cylinder 11 in the left-right direction.

The boost ram 13 is liquid-tightly fixed to the left side member of the mold clamping cylinder 11, and its right side is slidably and liquid-tightly inserted into the ram 12.
is formed. The mold clamping cylinder 11 is formed with an A chamber 15 that discharges oil when the ram 12 advances (moves to the right in the figure). Conduit 18 to check valve 17
connected by.

A solenoid switching valve 2 is connected downstream of the check valve 17 via a conduit 19.
It is connected to the 00A boat side, and the B boat is connected to the boost ram 13 by a pipe line 21. Also A'gLWi
The P boat of the switching valve 20 is connected to a hydraulic power source (not shown) through a line 22, and the T port' is connected to a tank 24 through a line 23.

A pyro 1.7 tod circuit 27 connected to the vent circuit 25 of the relief valve 16 and the valve closing side oil chamber 26 of the check valve 17
is provided with a throttle valve 28 in the middle and connected to the B boat and A boat of the B solenoid valve 29, respectively, and the B'wL solenoid valve 29
The P boat is connected to the hydraulic power source by a pipe 30 branched from the pipe 22, and the T boat of the B electromagnetic switching valve 29 is connected to the tank 2.
Connected to 4. In addition, the B chamber 31 of the mold clamping cylinder 11
is connected to the tank 24 via a C electromagnetic switching valve 36 from a conduit 32 in the illustrated state, and the P port of the same boat 36 is connected to the conduit 22 by a conduit 37.

Next, the operation of the embodiment described above will be explained. First, put the B solenoid switching valve 29 and the C solenoid valve 36 in the state shown in the figure.
When the iB switching valve 20 is switched to the chamber in position b, the pressure oil changes to P.
1 of pressure flows into the boost cylinder 14 through the line 21 and the boost ram 13, so the ram 12 moves forward at high speed. At this point, pressure oil is working in the vent circuit 25 of the IJ-) valve 16, so the relief valve 16 does not open, and the valve closing side oil chamber 26 of the check valve 17 is closed.
Since it is open to the check valve 17, the check valve 17 is open. Therefore, the oil in the A chamber 15 of the mold clamping cylinder 11 flows through the pipe line 18, the check valve 17, the pipe line 19, and the All! Magnetic switching valve 20
Then, as the ram 12 moves forward, it passes through the pipe 23 and is discharged into the tank 24 at zero pressure.

Then, just before the ram 12 moves further forward and the movable mold (not shown) comes into contact with the fixed mold (not shown), the B electromagnetic switching valve 29 is switched to the a position by a limit switch (not shown). By this switching, pressure oil acts on the valve closing side oil chamber 26 of the check valve 17, the valve body 33 is lowered, and the check valve 17 is closed. On the other hand, since the vent circuit 25 of the 1J IJ-F valve 16 is connected to the tank 24 via the B electromagnetic switching valve 29, the relief valve 16 can be relieved. As a result, since the check valve 17 is closed, the oil in the A chamber 15 of the mold clamping cylinder 11 that is discharged as the ram 12 moves forward passes through the relief valve 16. The pressure P2 becomes higher than the pressure P□ at which the valve 16 opens, and the forward speed of the ram 12 decreases. Here, the working area of the boost cylinder 14 is slightly larger than the working area of the A chamber 150, so the boost cylinder 1
The hydraulic pressure Pi of the chamber A 15 and the hydraulic pressure P2 of the chamber A 15 are almost balanced and provide an effective brake for the ram 12. Note that the magnitude of the brake force is determined by adjusting the relief valve 16. In this way, when the ram 12 moves forward at low speed and both molds come into contact, when the B electromagnetic switching valve 29 is switched again to the b position shown in the figure, the relief valve 16 is closed and the check valve 17 is closed so that the oil chamber 26 on the valve closing side is throttled. Since it is communicated with the tank 24 via the valve 28, it gradually opens and the hydraulic pressure P2 in the A chamber 15 gradually decreases, so that only the hydraulic pressure P1 in the boost cylinder chamber 14 acts.

At the same time as the B solenoid valve 29 is switched, the C solenoid valve 36 is also switched to the a position, and pressure oil acts on the B chamber 31 of the mold clamping cylinder 11, generating a strong mold clamping force.

If the relief valve is an electromagnetic proportional relief valve, the pressure gradient can be controlled, resulting in smoother control.

In the above description, the ram 12 is moved forward, but it is also possible to apply a brake to the ram 12 just before the backward limit when the ram 12 moves backward. When the ram 12 retreats, the pipe 1
Pressure oil flows into the pipe 8, and the pipe line 21 is connected to the tank. Therefore, at the downstream of the conduit 21, there is a +71J-
By installing the check valve 16 and the check valve 27, it is possible to apply a braking action to the ram 12 just before the ram 12 reaches its backward limit, as described above.

〔Effect of the invention〕

As explained above, the mold opening/closing hydraulic drive mechanism of the injection molding machine according to the present invention has a relief valve controlled by an electromagnetic switching valve and a pilot type check valve connected in parallel to the oil conduit that is discharged into the tank when the ram moves. Established. Therefore, when the ram is moving at high speed, the +71J-7 valve is closed and the check valve is open, so the oil flows into the tank through the check valve at pressure O, and the ram moves at high speed. On the other hand, when the ram reaches just before its stroke limit, the electromagnetic switching valve is switched, the check valve is closed, and the relief valve is enabled for relief, so the oil that returns to the tank becomes high enough to open the relief valve, applying a braking action to the ram. .

As a result, when the ram moves forward, the movable mold and the fixed mold come into smooth contact, and both molds are not damaged.

Further, even when the ram retreats, the ram and the moving die plate smoothly stop without generating an impact, which has the advantage of extending the life of the injection molding machine. In addition, in the above embodiment, the IJ-F valve was explained as having a vent control type, but it is not limited to this, and any type that performs the same action may be used. An electromagnetic proportional relief valve that controls pressure may also be used.

[Brief explanation of the drawing]

The figure is a mechanical diagram showing an embodiment of the present invention. 11... Mold clamping cylinder, 12... Ram, 13...
Boost ram, 16... Relief valve, 17... Check valve, 20... A electromagnetic switching valve, 28... B [ia
Switching valve, 9-

Claims (1)

[Claims] 1). A electromagnetic switching valve that controls the forward and backward movement of the main ram moved by the Poonu tram, and an oil pipe that is discharged into a tank by the movement of the main ram when the main ram moves forward or backward. A relief valve installed in the road, a pilot-operated check valve connected in parallel to the relief valve, a vent circuit of the relief valve, and an oil chamber on the valve closing side of the check valve are switched to a hydraulic source or tank. A mold opening/closing hydraulic drive mechanism for an injection molding machine consisting of a B electromagnetic switching valve and a B electromagnetic switching valve. 2) A mold opening/closing hydraulic drive mechanism for an injection molding machine according to claim 1, wherein the relief valve is an electromagnetic proportional relief valve.