JPS6140174B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a mold opening/closing device for an injection molding machine or a die casting machine (hereinafter referred to as a molding machine).

The molding machine attaches a fixed die and a movable die to each of the fixed and movable dies, advances the movable die towards the fixed die via a hydraulic cylinder, presses the two dies in close contact, and presses the two dies in close contact. Molten resin or molten metal is injected into a mold, and then, after cooling, the movable die is moved back and the molded product is removed from the mold. When moving the moving die forward, it is sufficient to move it forward against the weight of the moving die and the moving mold attached to it, so the hydraulic pressure of the hydraulic cylinder does not need to be high. It needs to move forward at high speed. When the two molds are in close contact with each other, the pressing force must be high to counter the injection pressure of the resin or molten metal.

If we use one hydraulic cylinder for the molding machine,
In order to obtain a high pressing force during pressing, a large diameter cylinder is required, and in order to move this large cylinder forward at high speed when the moving die is advanced, a large hydraulic pump is required, which is not desirable from the point of view of energy saving. . For this reason, a two-cylinder system has been proposed in which a small cylinder is used when the moving die moves forward, and a large diameter cylinder is used when pressing the die. However, the conventional two-cylinder mold opening/closing device has drawbacks such as a complicated switching mechanism for the two cylinders, increasing costs, requiring a large amount of hydraulic oil, and making it difficult to increase speed.

The present invention eliminates such drawbacks, and an object of the present invention is to provide a mold opening/closing device for a molding machine that has a simple mechanism and high reliability.

The following is a first example showing the details of the present invention.
This will be explained using figures. Fixed die 11 is fixed mold 12
It is connected to a mold clamping cylinder 14 having a diameter D ₁ through tie bars 13 and placed on the upper part of a bed (not shown). A movable die 16 facing the fixed die 11 and having a movable mold 15 fixed thereto is movably supported by tie bars 13. On the left side of the diagram of the moving die 16 is a piston rod 1 with a diameter of D ₃ .
7 is fixed, and a small piston 18 with a diameter D ₄ is slidably inserted into the cylinder part provided on one side, and the piston rod 17 penetrates the cover 19 into the mold clamping cylinder 14 in a fluid-tight manner. I'm getting into it.

A large piston 20 is slidably inserted into the mold clamping cylinder 14, and one side of the large piston 20 has a diameter
It forms a shaft portion of D ₃ and is attached to the piston rod 17 via a bolt or the like, and has an axial hole 21 in the center, which hole 21 is connected to a diametric hole 22 . A boost cylinder 23 with a diameter D ₂ is provided which liquid-tightly penetrates the bottom surface of the mold clamping cylinder 14 and is movable in the axial direction.One side of the boost cylinder 23 has a small diameter D ₆ and is connected to the large piston 2.
The small piston 18 extends inside the axial hole 21 of 0, and the small piston 18 is fixed to the tip thereof. A cylinder having an inner diameter _D5 is formed at the center of the boost cylinder 23, and a boost ram 25 supported by a housing 24 fixed to one side of the mold clamping cylinder 14 is inserted therein. 26 to 28 are electromagnetic switching valves 29, 3
1 is a pump and 30 is a tank. Also 32, 33
is a relief valve. The diameters D ₁ to D ₅ described above have the relationship of D ₁ >D ₂ >D ₃ >D ₄ >D ₅ and the relationship of D ² ₅ +D ² ₃ >D ² ₂ .

Next, the operation of the mold opening/closing device of the molding machine according to the present invention will be explained. When the movable die 16 moves forward (moves to the right in the figure), the electromagnetic switching valve 26 is energized and is in the right position, and the electromagnetic switching valve 27 is in the illustrated position with neither side AB energized, and the electromagnetic switching valve 28 is energized and in the left position. Therefore, the oil in the tank 30 is pressurized by the pump 29 and flows into the left chamber of the mold clamping cylinder 14 from the B port of the electromagnetic switching valve 26, and the electromagnetic switching valve 2 flows into the right chamber.
Pressure oil flows in from port B of 7. At the same time, it flows into the boost cylinder 23 via the boost ram 25. On the other hand, the oil in the tank 31 is operated by the pump 31 with hydraulic pressure independent of the pump 29, and acts on the small piston 18 through the electromagnetic switching valve 28. Note that when the movable die 16 is retracted, the large piston 20 and the boost cylinder 23 are separated from each other as shown in the figure, so the large piston 20 is in the relative position shown in the figure. moving die 16
If the hydraulic pressure is P, then the force to move it to the right is P× [π/4 (D ₁ ² − ^{D 2} ₆ + D ₅ ² )], and the force to move it to the left is P×
[π/4(D ₂ ² −D ₆ ² +D ₁ ² −D ₃ ² )].

Therefore, P×[π/4(D ₁ ² −D ₆ ² +D ₅ ² )]−P×[π
/4 (D ₂ ² - D ₆ ² ) + π/4 (D ₁ ² - D ₃ ² )]=P×π/4 (D ₅
² - D ₂ ² + D ₃ ² ) As described above, since D ₅ ² +D ₃ ² >D ₂ ² , the movable die 16 moves to the right, that is, moves forward. The amount of oil required at this time is the amount that flows into the diameter D ₅ of the boost cylinder 23, and since it is an extremely small amount that acts on the effective area π/4 (D ₅ ² − _{D 2} ² + D ₃ ² ), moves forward at high speed.

As the movable die 16 moves forward, when the movable die 16 comes into contact with a limit switch (not shown) or the like, the electromagnetic switching valve 28 is opened in response to the signal. Therefore, pressure oil acts on the left side surface of the small piston 18, causing the small piston 18 to move to the right along with the boost cylinder 23, and the boost cylinder 23 comes into contact with the large piston 20. At this point, the electromagnetic switching valve 26 remains unchanged and the b side of the electromagnetic switching valve 27 is energized, so pressure oil acts on the left side of the boost cylinder 23 and the large piston 20, and the right side of the large piston 20 is released into the tank 30. . As a result, the pressing force of the movable die 16 becomes P×[π/4 (D ₁ ² −D ₂ ² )+π/4D ₅ ² ], and the fixed mold 12 and the movable mold 15 are pressed with a great force and the molds are clamped. is completed.

Note that the b side of the electromagnetic switching valve 27 may be excited after an arbitrary delay time from the b side excitation timing of the electromagnetic switching valve 28.

When the movable die 16 is retracted, the electromagnetic switching valve 26 is energized, the a side of the electromagnetic switching valve 17 is energized, and the b side of the electromagnetic switching valve 28 is energized. As a result, the boost cylinder 23 moves to the left and separates from the large piston 20, pressure oil acts on both sides of the large piston 20, and the boost cylinder 23 is connected to the tank 30. Since D ₂ >D ₃ , the movable die 16 moves to the left, that is, moves backward, and at this time, the oil on the left side of the large piston 20 becomes a differential circuit that returns to the right side, so it moves backward at high speed.

FIG. 2 shows another embodiment of the present invention,
The only difference from FIG. 1 is the hydraulic circuit, such as the arrangement of the electromagnetic switching valve, and the mechanical parts are the same, so only the hydraulic circuit will be described. One side of the upper part of the electromagnetic switching valve 51 is connected to the left chamber of the mold clamping cylinder 14 via the check valve 52 to the boost ram 25, and the other side of the upper part is connected to the right side of the mold clamping cylinder 14 through the check valve 53. connected to the room. Note that the check valves 52 and 53 allow flow in the opposite direction when the pilot circuit is connected to the tank 30, and prevent flow in the reverse direction when pressure fluid is applied to the pilot circuit. One side of the lower part of the electromagnetic switching valve 51 is connected to the pump 29, and the other side of the lower part is connected to the tank 30. Solenoid switching valve 54
One side of the upper part is connected to the pilot circuit of the check valve 52, and the other side of the upper part is connected to the pilot circuit of the check valve 53.
One side of the lower part is connected to a pump 29, and the other side of the lower part is connected to a tank 30. Further, the connection of the electromagnetic switching valve 28 is the same as that shown in FIG.

The operation of the embodiment shown in FIG. 2 will be explained. When the movable die 16 moves forward, the electromagnetic switching valve 51 is energized on the a side, the electromagnetic switching valve 54 is on the b side, and the electromagnetic switching valve 28 is energized. As mentioned above, when the movable die retreats, the large piston 20 and the boost cylinder 23 are separated, so the hydraulic pressure is sent to the right side of the small piston 18 again, so the large piston 20 and the boost cylinder 23 are separated as shown in the figure. ing. In this state, the pressure oil from the pump 29 is sent to the boost cylinder 23 through the electromagnetic switching valve 51, and at the same time is sent to the left chamber of the mold clamping cylinder 14 through the check valve 52. One check valve 5 connected to the right chamber of the mold clamping cylinder 14
3 is closed because pressure oil is acting on the pilot circuit. Therefore, the oil in the right chamber of the mold clamping cylinder 14 flows into the left chamber through the hole 21, and the pressure oil sent between the boost cylinder 23 and the boost ram 25 causes the movable die 16 to move forward at high speed.

When the moving die 16 continues to move forward and comes into contact with a limit switch or the like, the electromagnetic switching valve 28 is deenergized, but the electromagnetic switching valve 51 remains unchanged. As a result, pressure oil flows into the left side of the small piston 18 and the boost cylinder 2
3 moves to the right and touches the large piston 20. At the same time, the electromagnetic switching valve 54 becomes neutral, and the pilot circuit of the check valve 53 is connected to the tank 30, so that the check valve 53 is connected to the tank 30.
open. That is, since the right chamber of the mold clamping cylinder 14 is connected to the tank 30, a large mold clamping force acts on the movable die 16.

When the movable die 16 is retracted, the electromagnetic switching valve 51 is
The solenoid switching valve 54 is on the a side and the solenoid switching valve 28 is on the a side.
b is excited. Therefore, the boost cylinder 23
moves to the left and leaves the large piston 20, pressure oil flows into the right chamber of the mold clamping cylinder 14 through the electromagnetic switching valve 51 and check valve 53, and the reverse valve connected to the left chamber of the mold clamping cylinder 14 Pressure oil acts on the pilot circuit of the check valve 52 to close the check valve 52. Therefore, the oil in the left chamber of the mold clamping cylinder 14 flows into the right chamber through the hole 21 at the center of the large piston 20, forming a differential circuit, so that the movable die 16 retreats at high speed.

As described above, the mold opening/closing device of the molding machine, etc. in the present invention uses a small-diameter boost cylinder to move forward at high speed when the die is moving forward, and after moving to the forward limit, a large piston is used to obtain a large mold clamping force. ,
Since the switching is performed by an electromagnetic switching valve, the mechanism is simple and the operation is reliable and highly reliable.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view including a hydraulic circuit according to one embodiment of the present invention, and FIG. 2 is a vertical cross-sectional view including a hydraulic circuit according to another embodiment of the present invention. 11...Fixed die, 12...Fixed mold, 14...
...Mold clamping cylinder, 15...Moving mold, 16...Moving die, 17...Piston rod, 18...Small piston, 20...Large piston, 21...Hole, 23
...boost cylinder, 25...boost ram.

Claims (1)

[Claims] 1. A fixed die to which a fixed mold is attached, a movable die to which a movable die is attached and moves forward or backward relative to the fixed die, and a piston rod fixed to the side of the movable die opposite to the fixed die and forming a cylinder at its end. a large piston fixed to the piston rod and sliding inside the clamping cylinder and having a hole in its center, and a large piston forming a cylinder in the center and moving through the bottom of the clamping cylinder and on one side thereof a boost cylinder inserted into the hole of the large piston, a small piston fixed to one end of the boost cylinder and sliding inside the cylinder of the piston rod, and a fixed boost ram inserted into the cylinder of the boost cylinder. A mold opening/closing device for a molding machine, wherein the movable die is advanced at high speed by the boost cylinder and boost ram when the movable die is advanced, and a large mold clamping force is generated by the large piston at the forward limit.