JPH0468130B2 - - 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, a booster ram type mold clamping device has been conventionally used.

In this device, a small-diameter booster ram is slidably connected to a large-diameter mold clamping ram. Pressure oil is supplied to the small-diameter cylinder chamber of the mold clamping ram through an oil passage provided in the booster ram, and high-speed mold closing is performed. At this time, pressurized oil in the oil tank is sucked into the rear oil chamber of the mold clamping ram, which is under negative pressure, through the opened prefill valve. After mold closing is completed, the pre-fill valve is closed and pressure oil is supplied to the rear oil chamber of the mold clamping ram to perform high-speed mold clamping.

(Problems to be Solved by the Invention) However, the conventional booster ram type mold clamping device described above has the following problems.

As the mold clamping ram moves forward at high speed, the rear oil chamber of the mold clamping ram becomes negative pressure, and its suction force replenishes oil from the aging tank to the rear oil chamber of the mold clamping ram. In order to prevent air entrainment, a capacity larger than that required by the mold clamping cylinder is required, which inevitably increases the size of the mechanical equipment. To compensate for this, high-speed movement tends to become unstable, and the oil passage between the oil tank and the rear oil chamber of the mold clamping cylinder, as well as the pre-fill valve, need large diameters with low flow resistance.For powerful mold clamping. At the time of switching, the pressure in the rear oil chamber is rapidly changed from negative pressure to high pressure, which tends to cause a shock, and it also takes time to increase the pressure, which slows down the molding cycle.

Therefore, in order to solve these problems, a mold clamping device as disclosed in Japanese Patent Laid-Open No. 53-42248 was proposed.

This device includes a mold clamping piston that slides into a mold clamping cylinder, and a mold clamping ram and a fast-feed advance cylinder that are substantially the same in shape on the front and rear surfaces of the mold clamping piston, respectively.
The front and rear oil chambers of the mold clamping cylinder are connected by an oil passage that can be opened and closed, and a small-diameter booster ram is fitted in the fast-feed advance cylinder. When supplying pressurized oil from the booster ram into the fast-feed advance cylinder to rapidly feed the mold clamping ram, by communicating the oil chambers before and after the mold clamping piston, oil moves from the front chamber to the rear chamber. However, due to the structure of this device, the total length of the mold clamping device is more than double the mold clamping stroke, which increases the size and weight of the device and increases manufacturing costs. There is a problem.

(Object of the Invention) The present invention has been made to solve the above problems, and its purpose is to prevent the rear oil chamber of the mold clamping ram from becoming negative pressure when opening and closing the mold. The purpose of the present invention is to provide a mold clamping device that can be structurally simplified, smaller, and lighter.

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

That is, a mold clamping ram whose tip is connected to a movable platen slides together, and a mold clamping cylinder is partitioned into the oil chamber B and the rear oil chamber A by the piston portion of the mold clamping ram, and The base end side is fixed to the rear wall, and the large diameter piston at the tip slides into the mold clamping ram from the rear, dividing the interior of the mold clamping ram into a front oil chamber D for mold closing and a rear oil chamber E for mold closing. At the same time, the oil chamber D
and a high-speed piston having oil passages for supplying pressure oil to the oil chamber E, respectively. a communication passage that communicates with the mold clamping ram, an on-off valve that slides freely forward and backward over the rear end of the mold clamping ram, and opens the communication passage when performing high-speed mold opening/closing; A through hole is drilled in the mold clamping ram to communicate the valve opening oil chamber F formed in the sliding portion of the valve opening with the oil chamber E, and a through hole is provided parallel to the mold clamping cylinder, and the tip of the rod is connected to the movable rod. An auxiliary cylinder that is connected to the panel and whose interior is divided into a rod-side oil chamber C and a rear chamber, and the rod-side oil chamber C of the auxiliary piston and the oil chamber B are connected by the auxiliary piston that is slid together. The sum of the effective pressure receiving area of the oil chamber B and the effective pressure receiving area of the oil chamber C is set to be approximately equal to the effective pressure receiving area of the oil chamber A, and the mold clamping ram is provided with an oil passage to perform high-speed mold opening and closing. When the oil chamber moves, the sum of the amount of oil moving from the oil chamber B and the oil chamber C through the communication path is approximately equal to the amount of oil moving from the oil chamber A through the communication path. It is characterized by what it did.

(Function) Pressure oil is supplied to the D chamber during high-speed mold closing, and at that time the on-off valve 25 opens and the oil in the unpressurized chambers A, B, and C moves through the oil path 36 and the communication path 22. Strong mold clamping is performed by pressurizing chamber A. At this time, the on-off valve 25 moves forward due to the pressure difference between the front and rear sides, and closes the communication passage 22.

At the time of high-speed type opening, pressure oil is supplied to chamber E, and at this time chamber F is also pressurized via chamber E, which causes the on-off valve 25 to retreat and open the communication passage 22, resulting in an unpressurized state. Oil in chambers A, B, and C moves through the oil passage 36 and the communication passage 22.

In the present invention, the C chamber of the auxiliary cylinder and the B chamber of the mold clamping cylinder are not pressurized for driving.
Therefore, its pressure-resistant structure can be simplified.

Moreover, the control of the on-off valve 25 can be performed reliably with a simple structure by communicating the E chamber and the F chamber.

When the valve body 41 is slid onto the large-diameter oil passage 40 of the oil passage communicating the E chamber and the D chamber, return oil from the E chamber flows into the D chamber when the D chamber is pressurized. This allows high-speed mold closing and high-speed mold opening to be performed at approximately the same speed. Also D
The indoor pressure reaches the F chamber via the E chamber, and the opening/closing valve 25 can be forcibly opened even when the mold is closed.
The movement of oil between chambers B and C is performed more smoothly and reliably.

(Embodiment) A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

In FIGS. 1 to 3, reference numeral 10 denotes a movable platen, which is guided by a tie bar 13 horizontally extending between a fixed platen 11 and a cylinder block 12 so as to be movable in the direction of the fixed platen 11.

A movable die 14 and a fixed die 15 are attached to opposing surfaces of the movable platen 10 and the fixed platen 11, respectively.

A known injection device 17 is provided on a machine stand 16 on the back side of the fixed platen 11 so as to be able to move toward and away from the fixed mold 15.

The cylinder block 12 is provided with a clamping cylinder 18 and an auxiliary cylinder 19 parallel to the clamping cylinder.

A mold clamping ram 20 whose tip end is connected to the rear surface of the movable platen 10 is inserted into the mold clamping cylinder 18 so as to be able to move forward and backward through the front cover 9.
As a result, the inside of the mold clamping cylinder 18 is divided into a front oil chamber B (hereinafter simply referred to as B chamber) and a rear oil chamber A (hereinafter simply referred to as B chamber). The A chamber and the B chamber communicate with each other through a communication passage 22 provided in the piston portion 21.

Although not shown in the drawings, the B chamber is connected to a hydraulic system via a relief valve set to a low pressure.

The part of the mold clamping ram 20 extending into the A chamber includes a large diameter part 23 extending from the piston part 21 and a small diameter part 24 extending from the large diameter part 23 and having a smaller diameter than the large diameter part. ing. On this small diameter portion 24, an on-off valve 25 that opens and closes the aforementioned communication passage 22 is slidably movable in the axial direction of the mold clamping ram 20. The on-off valve 25 is an annular piston, and its sleeve-shaped portion 26 is guided on the circumferential surface of the large-diameter portion 23, and the end surface of the sleeve-shaped portion 26 connects to the communication passage 22.
It is becoming possible to block the A cap 27 is screwed to the end face of the small diameter portion 24 to prevent the on-off valve 25 from coming off and to regulate the amount of movement. Open/close valve 25
Cylinder space F between the inner surface and the outer peripheral surface of the small diameter portion 24
(hereinafter simply referred to as room F).

Next, a high-speed piston 28 whose rear end is fixed to the inner rear wall of the mold clamping cylinder 18 is inserted into the mold clamping ram 20 through the cap 27 . The interior of the mold clamping ram 20 is closed by a high-speed mold closing chamber D (hereinafter simply referred to as D chamber) by the tip piston portion 29 of the high-speed piston 28.
It is divided into a mold opening room E (hereinafter simply referred to as E room). The D chamber and the E chamber are connected to a hydraulic system (not shown) outside the cylinder block 12 via an oil passage 30 and an oil passage 31 formed in the high-speed piston 28, respectively. On the other hand, the F chamber and E chamber communicate with each other through a through hole 32 provided in the mold clamping ram 20.

The auxiliary cylinder 19 includes an auxiliary piston 33.
is inserted through a front cover 34 that closes off the auxiliary cylinder 19, and the piston rod of the auxiliary piston 33 is connected to the back surface of the movable platen 10. Therefore, the auxiliary piston 33 slides within the auxiliary cylinder 19 in conjunction with the movable platen 10. The inside of the auxiliary cylinder 19 is divided into a front oil chamber C (hereinafter simply referred to as C chamber) and an air chamber 35 by the piston portion of the auxiliary piston 33, and the air chamber 35 communicates with the outside through a through hole. The B chamber and the C chamber communicate with each other through an oil passage 36 provided in the partition wall of the mold clamping cylinder 18 and the auxiliary cylinder 19.

In the present invention, the effective pressure receiving area of the front oil chamber B of the mold clamping cylinder 18 (the area obtained by subtracting the rod part area from the piston part area of the mold clamping ram 20) and the effective pressure receiving area of the front oil chamber C of the auxiliary cylinder 19 are The sum of the area (the area obtained by subtracting the rod area from the piston area of the auxiliary piston 33) is calculated as the area of the mold clamping cylinder 18.
It is set to be approximately equal to the effective pressure receiving area of the rear oil chamber A (the area obtained by subtracting the narrow diameter part area of the high speed piston 28 from the piston part area of the mold clamping ram 20).

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 D. At this time, the oil in chamber E is returned to the oil tank. Further, the oil in the B chamber and the C chamber, which is compressed by the movement of the movable platen 10, moves to the A chamber via the communication path 22. In this case room B and C
Since the sum of the effective pressure-receiving areas of the chambers is set to be approximately equal to the effective pressure-receiving area of chamber A, the amount of oil discharged from chambers B and C is equal to the amount of oil required by chamber A. There is no negative pressure inside the room. In addition,
Since chambers A, B, and C are in an unpressurized state, the on-off valve 25 moves to the position where it opens the communication passage 22 due to the resistance of the oil when the piston portion 21 of the mold clamping ram 20 moves. There is.

Strong mold clamping: Following high-speed mold closing by pressurizing chamber D, the flow rate of pressure oil supplied to chamber D is reduced to close the mold at low speed and low pressure (Fig. 2), and then chamber A is pressurized.

As a result, a pressure difference is generated before and after the on-off valve 25, so the on-off valve 25 moves forward, and the end surface of the sleeve-shaped part 26 comes into contact with the piston part 21 of the mold clamping ram, causing the communication passage 2
Close 2 (Figure 3). Therefore, the pressurized oil supplied to chamber A thereafter acts on the rear end surface of the mold clamping ram 20 to perform strong mold clamping. In this case, if the D chamber is pressurized at the same time, the output of the D chamber also acts as a strong mold clamping force.

In this state, the injection device 17 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,
The chamber is depressurized, chamber E is pressurized, and the mold is opened.

In this case, by pressurizing chamber E, F
Since the chamber is also pressurized, the on-off valve 25 moves back and
The chamber communicates with chamber B and chamber C, and as the mold clamping ram 20 and auxiliary piston 33 move back, the oil in chamber A flows into chamber B and chamber C.
Move to room C.

Also, the oil in chamber D is returned to the oil tank.

In the above embodiment, the mold clamping cylinder 18 and the auxiliary cylinder 19 are provided integrally, but they may be provided separately, and the oil passage between the B chamber and the C chamber is provided as an appropriate joint hose. Also good. Furthermore, the capacity of the auxiliary cylinders 19 may be divided and a plurality of sets may be provided.

FIG. 4 shows another embodiment.

In this embodiment, the rear inner diameter of the mold clamping cylinder 18 is larger than the inner diameter. The other configurations are exactly the same as those of the previous embodiment.

In this embodiment, during high-speed mold opening and closing, the piston portion 21 of the mold clamping ram 20 does not come into contact with the rear inner wall, so sliding resistance is reduced and the mold can be opened and closed at a higher speed. In addition, the movement of oil between chambers A, B, and C at this time is also performed with lower resistance through the gap between the piston portion 21 and the rear inner wall. During strong mold clamping, the piston part 21 moves forward to a position where it slides into the front inner wall, so strong mold clamping can be performed without any problem.

In this embodiment, since the rear large diameter portion serves as an escape space for the cutting tool, there is an advantage that the mold clamping cylinder 18 can be easily machined and the machining cost can be reduced.

FIG. 5 shows yet another embodiment.

In this embodiment, a plurality of mold clamping cylinders 18
are arranged in parallel, and one auxiliary cylinder 19 is shared by the plurality of mold clamping cylinders 18. The B chamber of each mold clamping cylinder 18 and the C chamber of the auxiliary cylinder 19 are connected by a hose joint 38 or the like. Also, A of the plurality of mold clamping cylinders 18
The total effective pressure receiving area of the chambers is set to be approximately equal to the sum of the effective pressure receiving area of the B chamber of the mold clamping cylinder 18 plus the effective pressure receiving area of the C chamber of the auxiliary cylinder 19.

As a result, in this embodiment as well, during high-speed mold opening and closing, oil moves between chambers A and B of each mold clamping cylinder 18 and chamber C of a single auxiliary cylinder 19 with almost no excess or deficiency of oil. Become.

In this embodiment, since a plurality of mold clamping cylinders 18 are provided, a strong mold clamping pressure of several thousand tons can be obtained.

In each of the above embodiments, it is preferable that the mold closing and mold opening speeds during high-speed mold closing and high-speed mold opening are approximately the same.
The oil supplied to the D chamber is combined with the return oil from the E chamber via an external valve (not shown) and supplied to the chamber so that the mold closing and mold opening speeds are approximately the same. There is.

Next, the embodiments shown in FIGS. 6 and 7 are constructed so that the mold closing and mold opening speeds are substantially the same without providing an external valve as described above.

In this embodiment, the oil passage 31 extending inside the high-speed piston 28 to communicate with the E chamber is also opened on the D chamber side. Therefore, the E chamber and the D chamber communicate with each other through the oil passage 31 and the opening 39 that opens into the E chamber.

On the other hand, a portion of the oil passage 31 sandwiching the opening 39 back and forth is formed into a large-diameter oil passage 40, and a valve body 41 is slidably fitted into the large-diameter oil passage 40. Reference numeral 42 designates a male thread with a flow path that forms the large diameter oil passage 40 portion and is screwed into a female thread provided at the end of the oil passage 31.

In the case of this embodiment, when the D chamber is pressurized during high-speed mold closing, the valve body 41 retreats as shown in FIG. 6, and the E chamber and D chamber communicate with each other. As a result, the E chamber is also pressurized, but since the output of the D chamber is greater, the oil in the E chamber flows into the D chamber, increasing the speed.

When opening the mold, the mold is opened by pressurizing chamber E as shown in FIG.
Cut off communication with the room. The oil in chamber D is returned to the tank.

This allows the mold to close and open at approximately the same speed.

In this embodiment, since no external valve or external piping is required, the structure is simple and costs can be reduced. Furthermore, the path of oil movement from chamber E to chamber D is shortened, flow resistance is reduced, and energy waste can be avoided.

Even more conveniently, since chamber F is pressurized via chamber E even when the mold is closed, the on-off valve 25 is reliably opened, and chamber A and chamber B can be reliably communicated with each other.

The mold clamping device according to the present invention can be suitably used as a mold clamping device for an injection molding machine or a die casting machine.

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,
It has the following unique effects.

During high-speed mold closing, the pressure inside the rear oil chamber of the mold clamping cylinder does not become negative, and the pressure can be increased in a short time during strong mold clamping.

Since the mold can be opened and closed by pressurizing only chambers E and D, almost no pressure is generated in chambers B and C during the entire cycle. Therefore, the front cover of the mold clamping cylinder, the auxiliary cylinder, the auxiliary piston, etc. do not require much rigidity, and can be small and simple in structure, making the device smaller, lighter, and ultimately cost-effective. .

The on-off valve acts only on the open side due to the F chamber, and the oil path only requires drilling a hole that spans the E and F chambers, and no external piping is required, making processing and assembly easy and durable. Excellent performance and safety. In addition, by inserting a valve body that opens and closes the oil passage in the large diameter oil passage between chambers E and D, there is no need for external valves or external piping to perform high-speed opening and closing at approximately the same speed. In addition, even when the mold is closed, pressure is applied to chamber F and the on-off valve is opened, so oil can be moved reliably and smoothly between chambers A, B, and C.

The auxiliary cylinder is not used for pressurizing, so
The movement of the movable plate is hardly affected, and the movable plate can move in a well-balanced manner without having to provide a plurality of movable plates.

[Brief explanation of the drawing]

The figures show a preferred embodiment of the mold clamping device of the present invention, in which Fig. 1 is a sectional view in the mold open state, Fig. 2 is a sectional view in high-speed mold closing, and Fig. 3 is a sectional view in strong mold clamping. It is a diagram. Fig. 4 is a sectional view showing another embodiment, Fig. 5 is a sectional view of an embodiment in which a plurality of mold clamping cylinders are arranged side by side, and Figs. 6 and 7 are partial sectional views showing still other embodiments. , Figure 6 shows when chamber D is pressurized,
FIG. 7 shows the case where chamber E is pressurized. 10...Movable plate, 11...Fixed plate, 12...Cylinder block, 13...Tie bar, 14...
Movable type, 15...Fixed type, 16...Machine base, 17...
...Injection device, 18...Mold clamping cylinder, 19...Auxiliary cylinder, 20...Mold clamping ram, 21...Piston portion, 22...Communication path, 23...Large diameter portion, 24...
...Small diameter part, 25...Opening/closing valve, 26...Sleeve shaped part, 27...Cap, 28...High speed piston,
29...Tip piston part, 30...Oil passage, 31...
...Oil passage, 32...Through hole, 33...Auxiliary piston,
34...Front cover, 35...Air chamber, 36...Oil passage,
38...Hose joint, 39...Opening, 4
0...Large diameter oil passage, 41...Valve body, 42...Male thread with flow path.

Claims (1)

[Scope of Claims] 1. A mold clamping cylinder in which a mold clamping ram whose tip end is connected to a movable platen is slid together and is partitioned into the oil chamber B and the rear oil chamber A by a piston portion of the mold clamping ram; The base end side is fixed to the rear wall of the mold clamping cylinder, and the large diameter piston at the tip slides into the mold clamping ram from the rear to form a mold closing front oil chamber D and a mold closing rear oil chamber D. A mold clamping device comprising a high-speed piston partitioned into an oil chamber E and having an oil passage for supplying pressure oil to the oil chamber D and the oil chamber E, respectively. and a communication passage that communicates the oil chamber B and the oil chamber A, and is slidably moved forward and backward over the rear end of the mold clamping ram, and opens the communication passage when performing high-speed mold opening and closing. an on-off valve; a through hole drilled in the mold clamping ram to communicate the oil chamber E with a valve-opening oil chamber F formed at a sliding portion of the on-off valve with the mold clamping ram; and the mold clamping ram. an auxiliary cylinder which is provided parallel to the cylinder, whose rod tip is connected to the movable platen, and whose interior is partitioned into a rod-side oil chamber C and a rear chamber by a slidable auxiliary piston; and a rod side of the auxiliary cylinder. Oil chamber C and the oil chamber B
The sum of the effective pressure receiving area of the oil chamber B and the effective pressure receiving area of the oil chamber C is set to be approximately equal to the effective pressure receiving area of the oil chamber A, in order to perform high-speed opening and closing. When the mold clamping ram moves, the sum of the amount of oil that moves from the oil chamber B and the oil chamber C through the communication path, and the amount of oil that moves from the oil chamber A through the communication path. A mold clamping device characterized in that: and are substantially equal to each other.