JPH0312493Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] This invention relates to an injection molding machine used for molding synthetic resin, particularly an injection molding machine having a booster ram type mold clamping mechanism.

[Conventional technology]

In general, a booster ram type mold clamping mechanism uses a small-capacity high-pressure pump to enable high-speed mold closing even with a large-capacity mold clamping device.The booster ram is inserted from the rear into the center of the mold clamping ram. At the same time, the rear oil chamber of the mold clamping cylinder is connected to an oil tank via a prefill valve, and when the prefill valve is opened to supply hydraulic oil into the booster ram and move the mold clamping ram forward at high speed, Hydraulic oil is sucked into the rear oil chamber of the mold clamping cylinder from the oil tank by negative pressure.

Also, close the prefill valve before mold closing is completed,
Supply hydraulic oil to the rear oil chamber and close it completely.
Subsequently, strong mold clamping can be performed, and when the mold is opened, the prefill valve is opened and hydraulic oil is supplied to the front oil chamber of the mold clamping cylinder, so that the hydraulic oil in the rear oil chamber is transferred to the prefill valve. It is also possible to return it to the tank via the

The hydraulic oil that is sucked into or discharged from the rear oil chamber by the high-speed opening and closing, and the hydraulic oil that is sucked into the pump to operate each part or the hydraulic oil that returns from the actuator are usually stored in one common oil tank. has been done.

[Problem that the invention attempts to solve]

However, in the above conventional injection molding machine, when the mold is opened at high speed, a large amount of hydraulic oil is rapidly returned into the oil tank from the rear oil chamber, and the hydraulic oil in the oil tank is agitated. This causes air to be drawn into the hydraulic fluid. When the hydraulic fluid is used again, there is a problem in that the hydraulic equipment cannot operate normally due to air bubbles in the hydraulic fluid.

At the same time, impurities that have settled on the bottom of the oil tank can also get caught up in the hydraulic oil, causing failure of hydraulic equipment, so in order to prevent this, conventional oil tanks have been designed to have more room than necessary. However, in that case, the equipment becomes large and a large amount of hydraulic oil is required, resulting in a problem of high cost.

This idea was devised to solve the above problem, and its purpose is to prevent the generation of air bubbles and the mixing of impurities in the hydraulic oil without increasing the size of the oil tank, and to eliminate the harmful effects caused by these. An object of the present invention is to provide an injection molding machine with a new configuration that can be cleaned.

[Means for solving the problem] The feature of this invention for the above purpose is that a booster ram is inserted into a cylinder provided in the mold clamping ram from the rear oil chamber of the mold clamping cylinder, and is connected to the rear oil chamber. In an injection molding machine in which an oil tank suction pipe is provided in the oil chamber and a pre-fill valve is provided at the boundary between the rear oil chamber and the oil chamber, the oil tank is connected to a pump suction port; The prefill tank is composed of a prefill tank section in which a suction pipe for supplying hydraulic oil into the mold clamping cylinder via a prefill valve is inserted, and the maximum oil level is set higher than the main tank section. A communication part is provided between the highest oil level part of the main tank part and the main tank part.

[Effect]

According to this idea, the large volume of hydraulic oil that accompanies high-speed opening and closing is carried out only in the prefill tank, and other actuators are driven by hydraulic oil sucked into the pump from within the main tank. .

Additionally, after the pre-fill valve closes and the mold is completely closed, the hydraulic fluid that is supplied under pressure is added to the hydraulic fluid that is sucked in during high-speed mold opening to further tighten the mold, and the added amount is It overflows from the communication part and returns to the main tank part.

〔Example〕

The mold clamping ram 1 is slidably inserted into the mold clamping cylinder 2, and its tip is connected to a movable platen on which a movable mold is attached as usual, although not shown in the drawings.

Further, a cylinder 3 having an opening at the rear end is provided in the axial direction in the center of the interior of the clamping ram 1, and a booster ram 5 located in the center of the rear oil chamber 4 of the clamping cylinder 2 is installed in the cylinder 3. It is inserted.

An oil chamber 9 is provided at the rear of the rear oil chamber 4 and communicates with a pre-filled tank portion 8 of an oil tank 7 via a suction pipe 6, and the oil chamber 9 and the rear oil chamber 4 are always closed by a spring 10. It is partitioned by a pre-fill valve 12 which is pressed in the direction and opens when pressure oil is supplied to the oil chamber 11.

The oil tank 7 is divided into two parts, the pre-filled tank section 8 and the main tank section 14, by a partition plate 13, and both oil chambers are connected to a communication section at the upper end of the partition plate, which corresponds to the highest oil level of the pre-filled tank section 8. 15
It is connected by

The capacity of the prefill tank section 8 is set so that the tip of the suction pipe 6 is below the oil level when the mold is closed, and the oil level is approximately equal to the lower part of the communication section when the mold is opened. It has sufficient capacity to operate each actuator in the machine, and is set at a position where the suction portion 7a does not suck in air when the oil level drops and does not suck in impurities settled on the bottom of the oil tank. Note that the air breather and suction filter of the oil tank are omitted in the drawing.

The suction portion 7a is connected to the suction port of a pump 17 driven by the motor 16, and the pump discharge port is connected to the cylinder 3, the rear oil chamber 4, and the oil chamber 11.
It is connected to the circuit of the front oil chamber 18, and switching valves 19, 20, and 21 are provided in the circuit, respectively. In addition, the drain port of each switching valve 19, 20, 21 is connected to the main tank section 14 with a drain pipe 2.
They are connected to each other via 2.

2 to 5 show some structures of oil tanks, and the oil tank 7 in FIG. 2 has a pre-fill tank section 8 and a main tank section 14.
A vertically long tank and a horizontally long tank are formed separately, and both are integrally connected by a communication section 15 formed by an oil pipe that opens to the highest oil level of the pre-filled tank section 8.

The oil tank 7 shown in FIG. 3 has the two tanks integrally connected at the side, and the communication section 15 of the oil pipe is connected from the partition wall 13a of the main tank section 8 to the pre-filled tank section 8. A case is shown in which the oil tank 7 is provided up to the maximum oil level, and FIG. 4 shows a case in which the oil tank 7 is formed by separating two tanks while maintaining the state shown in FIG. 3 above.

Furthermore, FIG. 5 shows an oil tank 7 in which a pre-filled tank part 8 is provided over the main tank part 14 and a communication part 15 is provided vertically.

Next, the operation will be explained.

In the mold open state shown in FIG. 1, the switching valve 19 is switched to the left, the switching valve 20 is switched to the neutral position, and the switching valve 21 is switched to the left symbol.

As a result, hydraulic oil is supplied to the oil chamber 11 and the cylinder 3, and the mold is closed at high speed. At the same time, the pre-fill valve 12 is opened, and the rear oil chamber 4 is supplied with negative pressure as the mold clamping ram 1 moves forward. Hydraulic oil in the pre-filled tank section 8 is sucked in through the suction pipe 6 and the oil chamber 9.

Immediately before mold closing is completed, the switching valve 19 is switched to the right symbol and the switching valve 20 is switched to the left symbol, and the prefill valve 12 is closed.
Supply hydraulic oil to the rear oil chamber 4, perform low pressure mold clamping,
After the mold is completely closed, the pressure of oil supplied to the rear oil chamber 4 is increased to perform strong mold clamping. At this time, the oil level in the prefill tank portion 8 is at the mold closing level.

Then, after injection filling and cooling steps, the process moves to mold opening process.

In the mold opening process, first, the switching valve 20 is switched to the right symbol to release pressure, and then the switching valve 20 is set to neutral, and the switching valve 19 is switched to the left, and the switching valve 21 is switched to the right symbol.

As a result, the oil chamber 11 is pressurized and the prefill valve 12 is opened, and at the same time, the front oil chamber 18 is pressurized, and the mold clamping ram 1 is moved back and the mold is opened. that time,
The hydraulic oil in the rear oil chamber 4 is rapidly returned to the prefill tank section 8 via the oil chamber 9 and the suction pipe 6, and agitation occurs there, but the air drawn in at that time is returned to the prefill tank section 8 through the oil chamber 9 and the suction pipe 6. calm down.

In addition, hydraulic oil is sucked in from the rear oil chamber 4 through the pre-fill valve 12, and after the pre-fill valve 12 closes, the rear oil is passed through the switching valve 20 in order to completely close the mold and forcefully clamp the mold. The hydraulic oil supplied to the chamber 4 is added and returned, but just before the mold opening is completed, this amount of hydraulic oil overflows from the communication part 15 at the top of the partition plate and is transferred to the main tank part 1.
Returned to 4.

In this embodiment, the drain from each actuator is guided to the main tank section 14, but if the capacity of each actuator is large and air is likely to be drawn in in the main tank section 14, the main tank section
A partition plate may be provided between the drain section 4 and the suction section, or the drain may be returned to the prefill tank section 8. Furthermore, if the communicating portion 15 is formed in a net shape, the effect of defoaming the overflow will be further enhanced.

[Effect of idea]

As mentioned above, this device has a booster ram 5 inserted into the cylinder 3 provided in the mold clamping ram 1 from the rear oil chamber 4 of the mold clamping cylinder 2, and an oil chamber 9 connected to the rear oil chamber 4 that is filled with oil. In an injection molding machine that is provided with a suction pipe 6 for the tank 7 and a pre-fill valve 12 at the boundary between the rear oil chamber 4 and the oil chamber 9, the oil tank 7 is connected to the main tank connected to the pump suction port. section 14, and a prefill tank section into which the suction pipe 6 for supplying hydraulic oil into the mold clamping cylinder 2 via the prefill valve 12 is inserted, and whose maximum oil level is set higher than that of the main tank section 14. 8, the agitation caused by the rapid return of a large volume of hydraulic oil upon mold opening occurs only in the prefill tank section 8, and the main tank section 8 is free from entrainment of air and impurities that have settled at the bottom of the tank. . In addition, in the pre-filled tank section 8, the air that has become bubbles in the hydraulic oil is stabilized and defoamed from the oil, and the main tank section 8
Since the air bubbles do not affect the hydraulic fluid No. 4, the normal operation of the hydraulic equipment is prevented from being disturbed by air or impurities caught in the hydraulic fluid.

In addition, a communication portion 15 extends between the highest oil level portion of the pre-fill tank portion 8 and the main tank portion 14.
is provided, so that even if the hydraulic oil supplied from the main tank section 14 to the rear oil chamber 4 is added and returned to the pre-fill tank for strong mold clamping, the added amount of hydraulic oil will overflow and flow into the main tank. Part 1
4, so there is no shortage of hydraulic oil in the main tank.

Furthermore, since the oil tank 7 is divided into a pre-fill tank section 8 and a main tank section 14, it can be designed with only the required performance of each section in mind, resulting in miniaturization of the equipment, cost reduction, etc. can be achieved.

Moreover, the prefill tank part 8 can be formed thin and high, and a large pressure head can be obtained, so that the suction resistance at the initial stage of suction into the rear oil chamber of the mold clamping cylinder can be reduced, resulting in even smoother operation. has.

[Brief explanation of the drawing]

The drawings show an embodiment of the injection molding machine according to this invention, and FIG. 1 is a schematic sectional view, and FIGS.
The figure is a schematic cross-sectional view showing each example of an oil tank. 1...mold clamping ram, 2...mold clamping cylinder, 3...
Cylinder, 4... Rear oil chamber, 5... Booster ram, 6... Suction pipe, 7... Oil tank, 8...
Pre-fill tank section, 9... Oil chamber, 12... Pre-fill valve, 14... Main tank section, 15...
...Communication department.

Claims (1)

[Scope of utility model registration request] A booster ram is inserted into the cylinder provided in the mold clamping ram from the rear oil chamber of the mold clamping cylinder, and an oil tank suction pipe is installed in the oil chamber connected to the rear oil chamber. In an injection molding machine equipped with a pre-fill valve at the boundary between the oil tank and the pump suction port, the main tank section connects the oil tank to the pump suction port, and the suction pipe that supplies hydraulic oil into the mold clamping cylinder via the pre-fill valve. inserted,
and a pre-fill tank part whose maximum oil level is set higher than the main tank part,
An injection molding machine characterized in that a communication part is provided between the highest oil level part of the prefill tank part and the main tank part.