JPH0462848B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a mold clamping device suitable for use in injection molding machines and die casting machines.

(Prior art) Direct pressure mold clamping devices used in injection molding machines and die casting machines require the mold to be opened and closed at high speed in order to shorten the molding cycle. Requires strong mold clamping force. In order to satisfy these contradictory effects, the mechanism of this type of direct pressure type mold clamping device is generally complex, and there are various types.

For example, FIG. 4 shows a booster ram type mold clamping device.

This device has a structure in which a large diameter mold clamping ram 10 and a small diameter booster ram 11 are slid together.
Then, pressure oil is supplied from the oil passage 12 provided in the booster ram 11 to the small diameter cylinder chamber 13 of the mold clamping ram 10, thereby achieving high-speed mold closing. At this time, oil is sucked from the oil tank 16 into the clamping ram rear oil chamber 14, which is under negative pressure, through the opened prefill valve 15. After the mold has been closed, the prefill valve 15 is closed and pressurized oil is supplied to the mold clamping ram rear oil chamber 14 to perform high-pressure mold clamping.

However, in the above conventional booster ram type mold clamping device, as the mold clamping ram moves forward at high speed, the mold clamping ram rear oil chamber 14 becomes negative pressure, and the suction force replenishes oil from the oil sump 16 to the rear oil chamber 14. Therefore, the following problems arise.

Since the oil tank requires a capacity greater than that required by the mold clamping cylinder to prevent air entrainment, the mechanical device inevitably becomes larger.

Since oil is replenished from the oil tank 16 to the rear oil chamber 14 of the mold clamping cylinder by suction, high-speed movement tends to become unstable, and the oil passage between the oil tank 16 and the rear oil chamber 14 of the mold clamping cylinder or the prefill valve 15 is also required to have a large diameter with low flow resistance.

When switching to strong mold clamping, the rear oil chamber 14 is rapidly changed from negative pressure to high pressure, which tends to cause a shock, and it also takes time to increase the pressure, slowing down the molding cycle.

Therefore, as in the mold clamping device shown in JP-A No. 53-42248, a mold clamping piston is slid into a mold clamping cylinder, and mold clamping rams of substantially the same diameter and speed are mounted on the front and rear surfaces of the mold clamping piston. A feed advance cylinder is provided respectively, and the front and rear oil chambers of the mold clamping cylinder are connected by an oil passage that can be opened and closed.The fast feed advance cylinder has a mold clamping device in which a small-diameter booster ram is slid together.

According to this mold clamping device, when supplying pressure oil from the booster ram into the fast-feed forward cylinder to rapidly feed the mold clamping ram, by communicating the oil chambers before and after the mold clamping piston, the front chamber can be moved from the front chamber to the rear chamber. Since the oil moves to the rear chamber, negative pressure is not generated in the rear chamber, and the problems of the booster ram type mold clamping device described above do not occur.

However, in the case of this mold clamping device, on the other hand, due to its structure, the total length of the mold clamping device is more than double the mold clamping stroke, which increases the size of the device, increases the weight of the device, and increases cost. There is a problem.

(Objective of the Invention) The present invention has been made to solve the above-mentioned problems, and its purpose is to achieve high performance while maintaining the same overall length as the conventional booster ram type. , simplification of the structure of the device,
The purpose of the present invention is to provide a mold clamping device that can be made smaller, lighter, and less expensive.

(Means for Solving the Problems) A mold clamping device according to the present invention for the above purpose has the following configuration.

That is, in a mold clamping device comprising a mold clamping cylinder that slides on a mold clamping ram whose tip end is connected to a movable platen, and a high-speed piston that slides on the mold clamping ram from behind, the mold clamping device is provided in parallel with the mold clamping cylinder, The interior is divided into a front oil chamber and a rear chamber by an auxiliary piston that slides together, and the rod tip of the auxiliary piston is divided by an auxiliary cylinder connected to the movable platen and a piston portion of the mold clamping ram. An oil passage that communicates the front oil chamber and rear oil chamber of the mold clamping cylinder and the front oil chamber of the auxiliary cylinder, and when performing high-speed mold opening and closing, the oil passage communicates with the rear oil chamber of the mold clamping cylinder. In addition, the sum of the effective pressure receiving area of the front part of the mold clamping ram and the effective pressure receiving area of the front part of the auxiliary piston is set approximately equal to the effective pressure receiving area of the rear part of the mold clamping ram, in order to perform high-speed mold opening and closing. When the mold clamping ram moves, the sum of the amount of oil that moves from the front oil chamber of the mold clamping cylinder and the front oil chamber of the auxiliary cylinder through the oil passage, and the rear oil amount of the mold clamping cylinder. It is characterized in that the amount of oil moving from the chamber through the oil passage is approximately equal.

(Function) In the present invention, the front oil chamber (A
chamber), rear oil chamber (B chamber) and auxiliary cylinder 29
The front oil chamber (E chamber) of is connected through an oil passage 36,
Moreover, since the sum of the effective pressure receiving area at the front of the mold clamping ram and the effective pressure receiving area at the front of the auxiliary piston is set equal to the effective pressure receiving area at the rear of the mold clamping ram, when the movable platen 20 and the auxiliary piston 34 are linked together during high-speed mold closing, , the amount of oil discharged from chambers A and E and supplied to chamber B is equal to the amount of oil required by chamber B, and therefore chamber B does not become under negative pressure.

High-pressure mold clamping is performed by supplying pressure oil to chamber B after the interlocking of chamber B is closed by the opening/closing means.

(Embodiments) Hereinafter, preferred embodiments of the present invention will be described in detail based on the accompanying drawings.

In FIGS. 1 to 3, reference numeral 20 denotes a movable platen, which is guided by a tie bar 23 horizontally extending between a fixed platen 21 and a cylinder block 22 so as to move forward and backward in the direction of the fixed platen 21.

A movable die 24 and a fixed die 25 are attached to opposing surfaces of the movable platen 20 and the fixed platen 21, respectively.

A known injection device 27 is provided on a machine base 26 on the back side of the fixed platen 21 so as to be able to move toward and away from the fixed mold 25.

The cylinder block 22 is provided with a mold clamping cylinder 28 and an auxiliary cylinder 29 parallel thereto.

A mold clamping ram 30 whose tip end is connected to the back surface of the movable platen 20 is slidably engaged with the mold clamping cylinder 28 so as to be able to move forward and backward.
The interior of the mold clamping cylinder 28 is divided into a front oil chamber A (hereinafter simply referred to as A chamber) and a rear oil chamber B (hereinafter simply referred to as B chamber) by the piston portion of the mold clamping ram 30.

A high-speed piston 31 whose rear end is fixed to the inner rear wall of the mold clamping cylinder 28 is slidably connected to the mold clamping ram 30 . Inside the mold clamping ram 30 is a high-speed piston 31.
A high-speed type closing chamber C (hereinafter simply C
It is divided into a mold opening room D (hereinafter simply referred to as D room). The C chamber and the D chamber are connected to a hydraulic system (not shown) provided outside the cylinder block 22 via oil passages 32 and 33 provided in the high-speed piston 31, respectively.

The auxiliary cylinder 29 includes an auxiliary piston 34.
The piston rod of this auxiliary piston 34 is connected to the back surface of the movable platen 20. Therefore, the auxiliary piston 34 slides within the auxiliary cylinder 29 in conjunction with the movable platen 20. Auxiliary cylinder 29
Inside, the large diameter portion of the auxiliary piston 34 forms a rear chamber that communicates with the front oil chamber E (hereinafter simply referred to as the E chamber) and the atmosphere.

An oil passage 36 is formed in the partition wall 35 between the clamping cylinder 28 and the auxiliary cylinder 29, and this oil passage 36 allows chambers A and B of the clamping cylinder 28 and chamber E of the auxiliary cylinder 29 to be connected to each other. It's communicating.

A high pressure switching cylinder 3 is installed near the oil passage 36 to the B chamber.
7 is formed, and the oil passage 36 is opened and closed by a high pressure switching piston 38 that slides on this high pressure switching cylinder 37. High pressure switching cylinder 3
7, an F chamber and a C chamber are formed by a high pressure switching piston 38.

39 and 40 are oil ports to the F chamber and C chamber.

Note that 41 is an oil port to the B chamber.

The characteristics of the present invention are the effective pressure receiving area of the front part of the mold clamping ram (the area obtained by subtracting the rod part area from the piston part area of the mold clamping ram 30) and the effective pressure receiving area of the front part of the auxiliary piston (the area obtained by subtracting the rod part area from the piston part area of the auxiliary piston 34). The sum of the effective pressure-receiving area at the rear of the mold clamping ram (the area obtained by subtracting the small diameter part area of the high-speed piston 31 from the piston part area of the mold clamping ram 30) is formed to be substantially equal to the mold clamping ram rear effective pressure receiving area. At the point.

Next, the operation will be explained.

High-speed mold closing: In the mold open state shown in FIG. 1, high-speed mold closing is performed by supplying pressure oil to chamber C. At this time, the oil in chamber D is returned to the oil tank. Further, the oil in chambers A and E compressed by the advancement of movable platen 20 moves to chamber B via oil passage 36. In this case, since the sum of the effective pressure receiving area of chamber A and the effective pressure receiving area of chamber E is set equal to the effective pressure receiving area of chamber B, the amount of oil discharged from chambers A and E and chamber B are Since the required amount of oil is the same, there is no negative pressure inside chamber B.

High-pressure mold clamping: Following high-speed mold closing by pressurizing chamber C, the flow rate of pressure oil supplied to chamber C is reduced to close the mold at low speed and low pressure (state in Figure 2), and then chamber F is pressurized. The high-pressure switching piston 38 is moved forward to close the oil passage 36 connected to the B chamber, pressure is released from the A and E chambers, and pressurized oil is supplied to the B chamber to perform strong mold clamping.

In this case, since the pressure in chamber B is not negative, the pressure is quickly increased.

In this state, the injection device 27 is moved forward while maintaining pressure,
Inject molten resin into a mold and perform the necessary molding.
After cooling and solidifying, proceed to the mold opening process.

Mold opening: After the resin injected into the mold has cooled and solidified, B
The chamber is depressurized, the C chamber is pressurized, the high-pressure switching piston 38 is moved back, and high-pressure, low-flow oil is supplied to the D chamber to perform strong mold opening. Thereafter, the flow rate is increased to open the mold at high speed, and just before the mold opening ends, the flow rate is reduced again to a low speed, and then the supply is stopped to complete the mold opening. At this time, the oil discharged from chamber B is the same as above.
Since the mold is returned to the room and there is no negative pressure in the B room, a smooth transition can be made to the next mold clamping process. In addition, C
The oil in the room is returned to the tank.

In the above embodiment, the mold clamping device of an injection molding machine was explained as an example, but a die casting machine,
Of course, it can also be used as a mold clamping device for other similar devices.

Furthermore, the mold clamping cylinder 28 and the auxiliary cylinder 29 may be provided separately, and the oil passage 36 may be formed with an appropriate joint hose, and the high-speed switching cylinder 37 may be provided with an appropriate external valve device (not shown). ).

Note that it is preferable that an operating circuit is formed between the C chamber and the D chamber during high-speed forward movement, and that the forward and backward speeds are the same.

Although the present invention has been variously explained above with reference to preferred embodiments, the present invention is not limited to these embodiments, and it goes without saying that many modifications can be made without departing from the spirit of the invention. It is.

(Effect of the invention) As described above, according to the mold clamping device according to the present invention,
There is no negative pressure in the rear oil chamber of the mold clamping cylinder during high-speed mold closing, and the pressure can be increased in a short time during strong mold clamping.

Further, since a large pressure does not act on the pressure oil in the auxiliary cylinder, there is no need for the auxiliary cylinder to have a pressure-resistant structure, and a simple structure is sufficient.

Furthermore, even after high-speed mold opening, the rear oil chamber of the mold clamping cylinder does not become negative pressure, allowing a smooth transition to the next mold clamping process.

Moreover, since the overall length can be reduced to about half of the conventional length, the device can be made smaller, lighter, and cheaper.

Further, it does not require a complicated valve mechanism like the conventional pre-fill valve, has a simple structure, is easy to design and manufacture, has excellent reliability, and is extremely suitable for practical use.

[Brief explanation of drawings]

The figure shows a preferred embodiment of the mold clamping device according to the present invention, and FIG. 1 is a sectional view in the mold open state;
FIG. 2 is a cross-sectional view showing the mold closing completed state, and FIG. 3 is a cross-sectional view during high-pressure mold clamping. FIG. 4 is a sectional view schematically showing a conventional booster ram type mold clamping device. 10...Mold clamping ram, 11...Booster ram,
12...Oil passage, 13...Small diameter cylinder chamber, 14...
...Rear oil chamber, 15...Pre-fill valve, 16...
...Oil tank, 20...Movable plate, 21...Fixed plate, 22...Cylinder block, 23...Tie bar, 24...Movable type, 25...Fixed type, 26
...Machine base, 27...Injection device, 28...Mold clamping cylinder, 29...Auxiliary cylinder, 30...Mold clamping ram, A...Front oil chamber, B...Rear oil chamber, 31...
High-speed piston, 32... Oil passage, C... High-speed type closed chamber, D... Type open chamber, 33... Oil passage, 34... Auxiliary piston, 35... Partition wall, 36... Oil passage, 37...
...High pressure switching cylinder, 38...High pressure switching piston, 39, 40...Oil port.

Claims (1)

[Scope of Claims] 1. A mold clamping device comprising: a mold clamping cylinder that slides together a mold clamping ram whose tip end is connected to a movable platen; and a high-speed piston that slides against the mold clamping ram from behind; an auxiliary cylinder that is partitioned into a front oil chamber and a rear chamber by an auxiliary piston that is provided in parallel and whose insides slide together, and the rod tip of the auxiliary piston is connected to the movable plate; and a piston section of the mold clamping ram. an oil passage that communicates the front oil chamber and rear oil chamber of the mold clamping cylinder and the front oil chamber of the auxiliary cylinder, which are divided by an opening/closing means that allows communication with the rear oil chamber of the cylinder, and the sum of the effective pressure receiving area at the front of the mold clamping ram and the effective pressure receiving area at the front of the auxiliary piston is set to be approximately equal to the effective pressure receiving area at the rear of the mold clamping ram, When the mold clamping ram moves to perform high-speed mold opening/closing, the sum of the amounts of oil that moves from the front oil chamber of the mold clamping cylinder and the front oil chamber of the auxiliary cylinder via the oil passage; A mold clamping device characterized in that the amount of oil moving from the rear oil chamber of the mold clamping cylinder through the oil passage is approximately equal.