JPH0352330B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an injection molding machine that is equipped with a mold opening/closing cylinder and a mold clamping cylinder and switches the moving speed of a movable mold from high speed to low speed when the mold closes. This invention relates to an injection molding machine in which a cylinder and a mold clamping cylinder are integrated to simplify the overall structure and reduce the size.

Generally, in an injection molding machine, in order to prevent the movable mold from colliding with the fixed mold during the mold closing operation, it is necessary to keep the moving speed and pressing force of the movable mold low at the end of mold closing.

However, it is not practical to move the movable mold at low speed throughout the entire mold closing stroke, as this will significantly increase the working time (cycle time). It is required to reduce the speed only.

For this purpose, a smaller mold opening/closing cylinder (booster cylinder) is attached in addition to the mold clamping cylinder, and when the mold is closed, the movable mold is moved at high speed by the mold opening/closing cylinder. Use a valve, etc. to supply hydraulic oil at a large flow rate into the mold clamping cylinder to prevent negative pressure inside the mold clamping cylinder, and to limit the amount of oil supplied to the mold opening/closing cylinder at the end of mold closing. to slow down the movement of the movable mold,
After that, a mold clamping cylinder is operated to clamp the mold under high pressure, which is often used.

However, in the above-mentioned conventional technology, the mold clamping cylinder and the mold opening/closing cylinder are separate bodies, which results in poor space utilization, resulting in a correspondingly larger device, and furthermore, it is necessary to replenish hydraulic oil to the mold clamping cylinder at a large flow rate. A prefill valve is required for this purpose, which has the disadvantage of complicating the structure and increasing costs.

An object of the present invention is to provide a structure in which a mold opening/closing cylinder and a mold clamping cylinder are integrated, in view of problems such as an increase in the size of the device and a complicated structure due to structural limitations of the injection molding machine based on the above-mentioned prior art. By this,
It is an object of the present invention to provide an excellent injection molding machine that eliminates the above-mentioned drawbacks and allows the device to be made smaller and has a simpler structure.

In accordance with the above object, the present invention has a structure in which a mold opening/closing cylinder and a mold clamping cylinder are integrally connected coaxially via a mold closing cylinder chamber, and one of the piston rods provided on both sides in the mold opening/closing cylinder By causing the piston rod of the mold clamping cylinder and the piston rod of the mold clamping piston of the mold clamping cylinder to protrude oppositely into the mold closing cylinder chamber, hydraulic oil is supplied into the mold closing cylinder chamber during high-speed mold closing.
The gist is that the mold opening/closing piston is moved separately from the mold clamping piston, so that the mold clamping piston does not need to be moved.

Next, embodiments of the present invention will be described below based on the drawings.

In FIG. 1, reference numeral 1 denotes a cylinder structure, which consists of a mold opening/closing cylinder 2 and a mold clamping cylinder 3, which are integrally connected on the same axis. A mold opening/closing piston 4 is installed inside the mold opening/closing cylinder 2, and the cylinder chamber is divided into a mold opening cylinder chamber 5 and a drain chamber 6.
Furthermore, inside the mold opening/closing cylinder 2, the drain chamber 6 is provided.
A closed cylinder chamber 8 is formed which is partitioned by a partition wall 7. A first piston rod 9 and a second piston rod 10 are provided on both sides of the mold opening/closing piston 4, and the first piston rod 9 is fixed to the movable mold plate 11, while the second piston rod 10 is fixed to the drawing wall 7. It projects into the mold-closing cylinder chamber 8 through the mold-closing cylinder chamber 8.

A mold-clamping piston 13 is housed inside the mold-clamping cylinder 3 and divides the cylinder chamber into a mold-clamping cylinder chamber 14 and a drain chamber 15, and its piston rod 16 protrudes into the mold-closing cylinder chamber 8. There is. The piston rod 16 and the second piston rod 10 of the mold opening/closing piston 4 are designed to abut each other at maximum mold opening. The pressure receiving area of the mold clamping piston 13 is larger than that of the first piston rod 10.

The mold opening cylinder chamber 5 of the mold opening/closing cylinder 22 communicates with a first electromagnetic switching valve 21 via an oil line 19 and a pipe 20, and the first switching valve 21 communicates with a first electromagnetic switching valve 21 through a pipe 22 and a pipe 20.
3, it is connected to a hydraulic power source P and an oil tank T. Further, the mold-closing cylinder chamber 8 is communicated with the first switching valve 21 through a conduit 24 having a check valve 25.

The first electromagnetic switching valve 21 is connected to the pipe line 2 of the hydraulic power source P.
2 to the pipe line 24 of the mold-closing cylinder chamber 8, and the pipe line 23 of the oil tank T to the pipe line 20 of the mold-opening cylinder chamber 5.
The first path 21a communicates with the pipe line 23 and the pipe line 2
The second path 21b that only communicates with 0 and the conduit 22
A third connecting pipe 20 and pipe 23 to pipe 24
It has a path 21c, and further includes first and second excitation coils 26a and 26b, which are controlled by an electric control circuit 27.

Note that 28 is a pilot line connecting the pipe line 20 and the check valve 25.

On the other hand, the mold clamping cylinder chamber 14 of the mold clamping cylinder 3 is selectively communicated with a hydraulic pressure source P and an oil tank T via a conduit 29 and a second electromagnetic switching valve 30. The second switching valve 30 has a first path 30a that communicates the pipe line 29 with the oil tank T, and a second path that communicates with the oil pressure source P.
The excitation coil 31 has a path 30b and is controlled by the electric control circuit 27.

32 and 33 are oil reservoirs, which are the drain chamber 6 of the mold opening/closing cylinder 2 and the drain chamber 15 of the mold clamping cylinder 3, respectively.
is connected to. Further, 35 is a movable mold attached to the movable mold plate 11, 36 is a fixed mold plate, 37 is a fixed mold, and 38 is a heating cylinder of the injection unit.
Furthermore, 40 is a mold closing detector, and 41 is a mold opening detector, each of which is connected to the electric control circuit 27.

In the above configuration, in the mold closing process, the first
As shown in the figure, the first
While energizing the first excitation coil 26a of the switching valve 21, the current to the second excitation coil 26b is cut off and switched to the first path 21a, the pipe line 20 is connected to the oil tank T, and the pipe line 24 is connected to the oil pressure source. Each communicates with P. On the other hand, the current to the excitation coil 31 of the second switching valve 30 is cut off and switched to the first path 30a, and the pipe line 29 is kept in communication with the oil tank T.

The hydraulic oil from the hydraulic source P is supplied to the pipe line 22, the first route 21a of the first switching valve 21, the pipe line 24, and the check valve 2.
5 into the mold-closing cylinder chamber 8, and acts on the first piston rod 10 of the mold opening/closing piston 4, pushing it to the right as shown by the arrow, moving the movable mold plate 11 at high speed, and making it movable. The mold 35 and fixed mold 37 are closed at high speed. In this case, the hydraulic oil in the mold-closing cylinder chamber 5 passes through the oil line 19, the pipe line 20, the first route 21a of the first switching valve 21, and the pipe line 23,
The oil is discharged into the oil tank T, while air is sucked into the drain chamber 6 from the opening of the oil reservoir 32.
During this time, no hydraulic oil is supplied to the clamping cylinder chamber 14, so the clamping piston 13 does not move.

As the mold closing process progresses and nears its end,
As shown in FIG. 2, the mold closing detector 40 detects that the movable mold plate 11 has reached the mold closing deceleration position, and
The excitation coil 31 of the second switching valve 30 is energized to
The flow is switched to the path 30b, and the hydraulic power source P and the pipe line 29 are brought into communication. Then, the hydraulic oil from the hydraulic source P is divided, flows into the pipe line 29 through the second path 30b of the second switching valve 30, and is introduced into the mold clamping cylinder chamber 14, causing the mold clamping piston 13 to move forward. Start. Because of this branching, the flow of hydraulic oil into the mold-closing cylinder chamber 8 is reduced, so the forward speed of the mold opening-closing piston 4 is reduced, and as a result, the mold-closing speed is reduced.

In this way, both the pistons 4 and 13 move simultaneously, and eventually the movable mold 35 on the movable mold plate 11 comes into contact with the fixed mold 37, and the movement of the movable mold plate 11 is restricted. Then, due to the regulation of the movable mold plate 11, no further hydraulic oil flows into the mold-closing cylinder chamber 8, and only flows into the mold-clamping cylinder chamber 14, and the pressure inside the mold-closing cylinder chamber 8 becomes high. , the check valve 25 in the conduit 24 is automatically closed.
A fluid lever is formed by the area ratio of the large-diameter mold-clamping piston 13 and the small-diameter first piston rod 10 of the mold opening/closing piston 4, and a large mold-clamping pressure acts on the first piston rod 10, making it movable. Type 35
The fixed mold 37 is clamped.

At this time, the air in the drain chamber 15 is forced out to the opening of the oil reservoir 33. At that time, the hydraulic oil drain contained in the expelled air is collected into the oil reservoir 33.

Next, after a predetermined injection process is performed, the mold opening process is started, and at this time, as shown in FIG. 3, the second excitation coil 26b of the first switching valve 21 is energized by the electric control circuit 27. together with the first excitation coil 2
The current to 6a is cut off and switched to the third path 21c, while the current to the excitation coil 31 of the second switching valve 30 is cut off and switched to the first path 30a. The hydraulic oil from the hydraulic source P passes through the third path 21c of the first switching valve 21, and is introduced into the mold opening cylinder chamber 5 via the pipe line 20 and the oil line 19. The mold opening/closing piston 4 is moved backward in the direction of the arrow by the hydraulic oil, and the movable mold 35 is separated from the fixed mold 37, and the mold is opened at high speed. At this time, the air in the drain chamber 6 is forced out to the opening of the oil reservoir 32. At that time, the hydraulic oil drain contained in the extruded air is collected into the oil reservoir 32.

On the other hand, during this time, high-pressure hydraulic oil is flowing through the pipe 20, so high pressure acts on the check valve 25 through the pilot 28, and the check valve 25 is maintained in a flowing state, and the mold-closing cylinder chamber is closed. The hydraulic oil in the oil tank T passes through the check valve 25, flows through the pipe line 24, and is returned to the oil tank T through the first switching valve 21.

Then, when the mold opening/closing piston 4 retreats until the tip of the first piston rod 10 comes into contact with the tip of the piston rod 16, the mold closing piston 13
is also pushed back by the mold opening/closing piston 4 which is retreating,
The hydraulic oil in the mold clamping cylinder chamber 14 is discharged from the pipe line 29 to the oil tank T via the first path 30a of the second switching valve 30, and air is discharged into the drain chamber 15 from the opening of the oil reservoir 33. It gets sucked in.

Next, as shown in FIG. 4, when the mold opening process progresses and reaches the end point, the mold opening detector 41
detects that the movable mold plate 11 has reached the mold opening stop position, and switches the path of the first switching valve 21 to the second path 21b by the electric control circuit 27. In this state, the mold opening cylinder chamber 5 communicates with the oil tank T, and at the same time, the pilot pressure to the check valve 25 is released, so the check valve 25 operates and the mold closing cylinder chamber 8 is shut off. Then, the mold opening/closing piston 4 stops, and the mold opening of the movable mold plate 35 is completed and stops, resulting in a stable state. Of course, in this case, when the mold opening/closing piston 4 stops, the mold clamping piston 1
3 also stops.

As described above, according to the present invention, in an injection molding machine that switches the mold closing speed from high speed to low speed at the end of the mold closing process, a mold opening/closing cylinder and a mold clamping cylinder each have a mold opening/closing piston connected to a movable mold. are integrally connected on the same axis, so that one of the piston rods provided on both sides of the mold opening/closing piston and the piston rod of the mold clamping piston in the mold clamping cylinder protrude oppositely into the mold closing cylinder chamber. As a result, hydraulic oil is supplied to the mold-closing cylinder chamber to move the mold-closing piston forward and close the mold at high speed.During this time, one of the mold-clamping pistons does not move, so the mold is closed. There is no need to replenish hydraulic oil into the cylinder, and the conventionally necessary hydraulic oil replenishment devices such as prefill valves can be omitted, simplifying the structure and reducing costs. It produces excellent effects.

Moreover, since both cylinders are connected on the same axis,
It also has the effect of improving space utilization and making the whole structure more compact.

Furthermore, at the end of the mold-closing process, the mold-closing speed can be reduced simply by diverting a portion of the hydraulic oil and introducing it into the mold-clamping cylinder by operating the switching valve.
Since the mold is brought into contact at a low speed and then the mold clamping process is automatically started, there is an advantage that the operation is easy.

[Brief explanation of drawings]

The figures show an embodiment of the present invention, in which Fig. 1 is an explanatory diagram of the operation of the mold closing process, Fig. 2 is an explanatory diagram of the operation of the mold closing deceleration and mold clamping process, and Fig. 3 is an explanatory diagram of the operation of the mold opening process. An explanatory diagram of the operation, FIG. 4 is an explanatory diagram of the stopped state. 2... Mold opening/closing cylinder, 3... Mold clamping cylinder,
4... Mold opening/closing piston, 5... Mold opening cylinder chamber,
6... Drain chamber, 7... Drawing wall, 8... Mold closing cylinder chamber, 9... First piston rod, 10... Second
Piston rod, 11... Movable mold plate, 13... Clamping piston, 14... Clamping cylinder chamber, 16...
Piston rod, 21... First switching valve, 30...
Second switching valve, P...hydraulic source, T...oil tank.

Claims (1)

[Claims] 1 In an injection molding machine that is equipped with a mold opening/closing cylinder 2 and a mold clamping cylinder 3 and switches the moving speed of a movable mold 35 from high speed to low speed when the mold closes, the mold opening/closing cylinder 2 and mold clamping cylinder 3 are coaxially arranged. The mold opening/closing cylinder is connected to a mold opening/closing cylinder chamber 5 separated by a mold opening/closing piston 4.
and a drain chamber 6, and a mold-closing cylinder chamber 8 partitioned from the drain chamber by a dividing wall 7, and piston rods 9, 10 are provided on both sides of the mold opening/closing piston, one of which The first piston rod 9 protrudes from the mold opening/closing cylinder and is fixed to the movable mold plate 11, while the other second piston rod 10 extends slidably through the partition wall and protrudes into the mold closing cylinder chamber. A piston rod 16 of a mold clamping piston 13 of the mold clamping cylinder projects into the mold closing cylinder chamber so as to face the second piston rod, and a mold opening cylinder chamber 5 and a mold closing cylinder chamber 8 of the mold opening/closing cylinder 2 are The mold clamping cylinder chamber 13 of the mold clamping cylinder 3 is selectively communicated with the hydraulic pressure source P and the oil tank T via the first switching valve 21, respectively, while the mold clamping cylinder chamber 13 of the mold clamping cylinder 3 is connected to the hydraulic pressure source P and the oil tank T via the second switching valve 30. An injection molding machine characterized in that the T is selectively communicated with.