JPH07117090A - Mold clamping device of injection molding machine - Google Patents

Abstract

PURPOSE:To drive a movable plate at a high speed though a structure is simple and inexpensive by clamping the movable plate having a movable mold attached thereto to a fixed plate having a fixed mold attached thereto by a hydraulic cylinder and a piston mechanism. CONSTITUTION:A fixed mold 5 is attached to a fixed plate 1 and a movable mold 6 is attached to a movable plate 4 and pressure oil is supplied to the drive chamber 2 on the right side of the piston 22 of an auxiliary cylinder device 20. Since a piston rod 24 is fixed to the fixed plate 1, the movable plate 4 is driven toward the fixed plate 1 at a high speed by a cylinder 21. At this time, a three-position electromagnetic valve 42 and a spring energizing electromagnetic valve 49 reflux the operation oil of the oil chambers 15,15 positioned on the left side of a cylinder 13 to oil pressure chambers 14,14 through a return pipeline 45, a connection pipeline 47, a pilot operation check valve 48 and a mold clamping pipeline 44.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a direct pressure type in which a movable plate to which a movable mold is attached is clamped by a hydraulic cylinder / piston mechanism with respect to a fixed plate to which a fixed mold is attached. The present invention relates to a mold clamping device of an injection molding machine.

[0002]

2. Description of the Related Art A direct pressure type mold clamping device is known as one of mold clamping devices for an injection molding machine. As is well known, the direct pressure type mold clamping device includes a mold clamping housing fixed to a base. A mold clamping cylinder is attached to this mold clamping housing. The piston of the mold clamping cylinder is directly connected to the movable platen. Therefore, when pressure oil is supplied to, for example, the cylinder head side of the mold clamping cylinder, the movable platen is driven toward the fixed platen and the mold is clamped. When supplied to the rod side, the movable plate is separated from the fixed plate. As described above, since the movable platen is directly driven by the mold clamping cylinder, the direct pressure type mold clamping device has a simpler structure as compared with the mold clamping device equipped with the toggle mechanism and the mold clamping device. It has the feature that thickness adjustment is unnecessary. However, since the mold clamping housing is provided, there are disadvantages that the cost is high and that it takes a long time to drive the movable plate. That is, the mold clamping device is required to have a large mold clamping force that prevents the mold from opening due to the resin pressure injected into the mold and the cavity. To obtain this large mold clamping force, the diameter of the cylinder is relatively large. It has been selected. Therefore, the movement of the piston is slow, the driving speed of the movable plate is low, and it takes a long time.

Therefore, in order to shorten the injection molding cycle, a direct pressure type mold clamping device which can drive a movable plate at a high speed to a mold touch position is disclosed in, for example, Japanese Patent Laid-Open No. 4-2249.
Proposed in No. 10. This mold clamping device is composed of a fixed tie plate, a movable tie plate, a rear plate, and the like. A piston portion is formed on the four tie rods connecting the fixed tie plate and the rear plate, and the end portion of the cylinder provided so as to surround the piston portion is fixed to the moving tie plate.
The pressure receiving areas of the piston portions of the four tie rods are paired and are different from each other. Therefore, when pressure oil is simultaneously supplied to the oil chambers on both sides of the piston portion of the pair of cylinders, the moving tie plate is driven in the mold clamping direction due to the difference in the pressure receiving area, and is moved to the oil chambers on both sides of the other pair of cylinders. Similarly, when pressure oil is supplied simultaneously, the mold is driven in the mold opening direction. If pressure oil is simultaneously supplied to one of the oil chambers of the four cylinders, the mold is clamped.

[0004]

As described above, the conventional direct pressure type mold clamping machine requires a mold clamping housing, resulting in high cost, a large diameter of the mold clamping cylinder, and a large amount of hydraulic oil. There is. On the other hand, in the mold clamping device proposed in Japanese Patent Laid-Open No. 4-224910, the piston portion is formed on the four tie rods that connect the fixed tie plate and the rear plate. I can't find it. Moreover, since the pressure receiving areas of the oil chambers on both sides of the piston portion are different, the advantage that the pressure oil can be simultaneously supplied to drive the moving plate at high speed is also recognized. Furthermore, it is also possible to supply pressure oil to the one having a wider pressure receiving area and perform mold clamping with a large force.

However, there are some points to be improved. For example, when pressure oil is simultaneously supplied to the oil chambers on both sides of the pistons of a pair of cylinders to drive the moving plate at high speed, special measures are taken to supply and discharge the pressure oil in the oil chambers of the other pair of cylinders. Therefore, it is conceivable that the oil chamber of the other pair of cylinders is empty, for example. If it is empty, the mold clamping operation cannot be started immediately after the driving of the moving plate is completed. That is, since the oil chamber of the cylinder that drives the moving plate is filled with pressure oil or hydraulic oil, the mold clamping action occurs immediately when the pressure oil is supplied, but the mold clamping force obtained by these pair of cylinders is , Only half. It takes time for the pressure oil to be supplied to the oil chambers of the other pair of empty cylinders and the mold clamping force is generated, and the prescribed mold clamping force cannot be obtained as a whole. Become. As a countermeasure against this, it is conceivable that the oil chambers of the other pair of cylinders are always filled with hydraulic oil. However, since the pressure receiving areas are different, it is expected that the pipeline structure will be complicated. Therefore, according to the present invention, the mold clamping device of a direct pressure type injection molding machine is capable of driving the movable plate at a high speed and having a mold clamping action immediately after the driving, although the structure is simple and inexpensive. Is intended to provide.

[0006]

In order to achieve the above object, the present invention has a fixed plate to which a fixed mold is attached, a movable plate to which a movable mold is attached, and a fixed plate fixed to a base. And the fixed plate and the fixed plate are coupled by a plurality of tie rods, and the movable plate is guided by these tie rods and clamped to the fixed plate by a hydraulic cylinder / piston mechanism. Is a mold clamping device configured to be driven in a mold clamping direction or a mold opening direction by a driving means of the hydraulic cylinder / piston mechanism, the end portion of which is fixed to the tie rod and the movable plate. And a cylinder that is arranged so as to surround the cylinder, and that receives a hydraulic chamber defined on both sides by a piston portion formed on the tie rod. Area with equal the two hydraulic chambers is configured to communicate via an openable valve mechanism.

[0007]

When the movable plate is driven in the mold clamping direction with respect to the fixed plate, or in the mold opening direction in which it is separated,
It is driven at high speed by another driving means such as another hydraulic cylinder / piston unit. At this time, the hydraulic chambers defined on both sides by the piston part of the hydraulic cylinder / piston mechanism are
Since the fluid is communicated via the openable / closable valve mechanism, when the movable plate is driven, that is, when the cylinder moves, the hydraulic oil in one hydraulic chamber moves to the other hydraulic chamber. When the movable plate mold touches the fixed plate mold, pressure oil is supplied to the hydraulic cylinder / piston mechanism to start the mold clamping operation. At this time, the valve mechanism that can be opened and closed is in the closed state,
Or close it. The molten resin is injected into the cavity of the mold that has been clamped, as is well known.

[0008]

EXAMPLES Examples of the present invention will be described below. As shown in FIG. 1, the mold clamping device according to the present embodiment includes a plurality of tie rods 10, 4, ..., And a cylinder 13 that cooperates with each of these tie rods 10, 10 ,. , 13, ..., Auxiliary cylinder device 20, and a hydraulic circuit. As is well known, a mold device driven or clamped by this mold clamping device includes a fixed plate 1 fixed on a base K and a fixed plate 2 similarly fixed on the base K. It is roughly configured by a movable plate 4 which is provided on the rail 3 on the base K so as to be movable in the left-right direction in the drawing. A fixed die 5 is attached to the fixed platen 1, and a movable die 6 is attached to the movable platen 4.

The tie rods 10 and 1 are attached to the fixed plate 2.
One end of 0, ... Is fixed. The other end is fixed to the fixed platen 1 with nuts 11, 11, .... As a result, the fixed plate 1 and the fixed plate 2 are connected to each other by the four tie rods 10, 10, ...
And the movable platen 4 has these tie rods 10, 10, ...
By this, it is designed so that it can be moved left and right. The tie rods 10, 10, ... Also function as piston rods of the hydraulic cylinder / piston mechanism, and the pistons 12, 1 are provided at the portions located between the movable platen 4 and the fixed plate 2.
2, ... are formed. And the pistons 12, 12 ...
Cylinders 13, 13, ... Are provided so as to surround the. The end portions of the cylinders 13, 13, ... Are fixed to the movable platen 4.

The diameters of at least the portions of the tie rods 10, 10, ... Which are located in the cylinders 13, 13, ... Are the same. Therefore, by the pistons 12, 12, ...
Hydraulic chambers 1 located on the right side, formed on both sides of it
The pressure receiving areas of the left side oil chambers 15, 15, ... Are equal.

The auxiliary cylinder device 20 for driving the movable platen 4 toward the fixed platen 1 or in the direction away from the stationary platen 1,
In this embodiment, it is composed of a piston / cylinder unit. That is, it is composed of a cylinder 21 and a piston 22 movably provided in the cylinder 21. The end of the cylinder 21 is fixed to a flange 23 that is integral with the movable platen 4. And piston rod 24
Is slidably passed through the flange 23 and fixed to the flange 25 of the stationary platen 1 by a nut 26. A pump that supplies a pressure oil to the piston / cylinder unit has a relatively low discharge pressure but a large discharge amount. Therefore, when pressure oil is supplied to the drive chamber 27 on the right side of the piston 22, the movable platen 4 is driven at high speed in the direction of the fixed platen 1, and when pressure oil is supplied to the return chamber 28 on the left side, the movable platen 4 is fixed. It is driven at a high speed in the direction of mold opening apart from 1.

The hydraulic chambers 14, 1 of the cylinders 13, 13, ...
4, while supplying pressure oil to the hydraulic chambers 14, 14, ...
The hydraulic circuit for supplying / discharging or exchanging hydraulic oil between the oil chambers and the oil chambers 15, 15, ... Is shown in FIG. That is, a 3-position solenoid valve 42 and a pilot-operated check valve 43 are interposed in the discharge pipe 41 of the pump 40, and the pressure oil that has passed through the pilot-operated check valve 43 is hydraulically fed from the mold clamping pipe 44. It is adapted to be supplied to the chamber 14. The oil chamber 15 and the tank T are connected by a return pipe line 45,
A check valve 46 that allows the flow of hydraulic oil toward the tank T is provided in the return pipe 45. Further, the return conduit 45 and the mold clamping conduit 44 are connected by a communication conduit 47, and a pilot operation reverse flow is unconditionally supplied from the oil chamber 15 to the hydraulic chamber 14 in this communication conduit 47. A stop valve 48 is interposed. The pilot operated check valve 48 is made conductive by the pilot pressure of a spring-biased solenoid valve 49. An unload valve 50 is provided in the discharge pipe line 41 of the pump 40.

Next, the operation of the above embodiment will be described. As shown in FIG. 1A, a fixed mold 5 is attached to the fixed platen 1, and a movable mold 6 is attached to the movable platen 4, and the mold clamping will be described. Pressure oil is supplied to the drive chamber 27 on the right side of the piston 22 of the auxiliary cylinder device 20. Then, since the piston rod 24 is fixed to the fixed platen 1, the movable platen 4 is driven at high speed in the direction of the fixed platen 1 according to the cylinder 21. That is, it is driven at high speed to the die touch position. At this time, the 3-position solenoid valve 42 and the spring-biased solenoid valve 49 are connected to each other as shown in FIG.
, The oil chamber 15 located on the left side of the cylinder 13 is located at the C and a positions, respectively.
The working oil of 15, ... Recirculates to the hydraulic chambers 14, 14, ... Through the return pipe 45, the connecting pipe 47, the pilot operation check valve 48, and the mold clamping pipe 44. Oil chambers 15, 15, ...
, The pressure receiving areas of the hydraulic chambers 14, 14, ... Are equal, so the hydraulic oil in the oil chambers 15, 15 ,.
It will move to 14, ...

When the auxiliary cylinder device 20 is driven at a high speed to the mold touch position, this is detected and the 3-position solenoid valve 42 is switched to the B position. Then, high-pressure pressure oil from the pump 41 passes through the pilot-operated check valve 43 and the mold clamping line 44, and the hydraulic chambers 14, 14,
Supplied to ... The tie rods 10, 10, ..., That is, the pistons 12, 12 ,.
Are clamped to the fixed platen 1. At this time, hydraulic chamber 1
Since hydraulic oil has already been filled in 4, 14, ..., The mold clamping action occurs immediately when the pressure oil is supplied. As is well known in the art, molten resin is injected into the cavities formed in the fixed mold 4 and the movable mold 5 for molding.

Waiting for cooling and solidification, the 3-position solenoid valve 4
2 to the C position and the spring biased solenoid valve 49 to b
By switching to the position, pressure oil is supplied to the return chamber 28 on the left side of the auxiliary cylinder device 20. Then, the movable platen 4 is opened at high speed for the reason described above. The molded product is ejected by the ejector pin. Take out the molded product with a take-out machine. During this mold opening operation, the spring-biased solenoid valve 49 is switched to the b position, so the hydraulic oil in the mold clamping pipe line 44 is transferred from the spring-biased solenoid valve 49 to the pilot operated check valve 48. , Acts as pilot pressure, and the pilot-operated check valve 48 is in a state in which hydraulic oil flows in the opposite direction. Therefore, as described above, the hydraulic oil in the hydraulic chambers 14, 14, ...
7, through the pilot-operated check valve 48 and the return pipe 45, to flow into the oil chambers 15, 15 ,. Thereafter, the movable platen 4 is driven as described above, and the mold is clamped and then injection-molded.

The hydraulic chambers 14, 14 of the cylinder 13 are
When the hydraulic oil inside is to be drained, the 3-position solenoid valve 42 is set to the A position. Then, the pressure oil from the pump 40 acts as pilot pressure on the pilot operation check valve 43, and the pilot operation check valve 43 becomes conductive. When the movable platen 4 is driven in the mold opening direction by the auxiliary cylinder device 20, the hydraulic oil in the hydraulic chambers 14, 14, ... Of the cylinder 13 is discharged to the tank T through the pilot operated check valve 43.

The present invention is not limited to the above embodiment, but can be implemented in various forms. For example, in the communication line 47,
Although the pilot operated check valve 48 is provided, a simple electromagnetic opening / closing valve may be provided instead of this valve. Then, when the mold is clamped, the electromagnetic opening / closing valve can be closed, and when the movable platen 4 is driven, it can be opened. Further, although the auxiliary cylinder device 20 is shown as an example implemented by a piston / cylinder unit, it may be directly driven by an electric motor by another drive device such as a rack and pinion mechanism. Although the operation of the above-described embodiment has been described as being operated manually, it is obvious that a control device can be provided and operated automatically. Further, FIG. 1B shows that one pump 40 supplies pressure oil to one cylinder 13, but four cylinders 1
It is also clear that it is possible to supply 3, 13, ... Simultaneously.

[0018]

As described above, according to the present invention, the tie rod connecting the fixed plate and the fixed plate is configured as a rod of a hydraulic cylinder / piston mechanism for mold clamping. Mold clamping housing is unnecessary,
An advantage of being mechanically cheaper than that of the conventional direct pressure type mold clamping device is obtained. Further, since the pressure receiving areas of the hydraulic chambers defined on both sides by the piston portion formed on the tie rod are equal, and both hydraulic chambers communicate with each other through the openable / closable valve mechanism, it is possible to use other drive devices. When the movable plate is driven, the hydraulic fluid in one hydraulic chamber moves through the valve mechanism that can be opened and closed to the other hydraulic chamber. Therefore, the hydraulic chamber is always filled with hydraulic oil, and the effect of mold clamping is obtained immediately when pressure oil is supplied to the hydraulic chamber, which is a unique effect of the present invention.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of a mold clamping device according to the present invention, in which (a) is a schematic sectional view of the mold clamping device and (b) is a hydraulic circuit diagram.

[Explanation of symbols]

 1 Fixed plate 2 Fixed plate 4 Movable plate 10 Tie rod 12 Piston 13 Cylinder 14 Hydraulic chamber 15 Oil chamber 20 Auxiliary cylinder device

Claims (1)

[Claims] 1. A fixed plate (1) to which a fixed mold (5) is mounted, a movable plate (4) to which a movable mold (6) is mounted, and a fixed plate (fixed to a base (K). 2), the fixed plate (1) and the fixed plate (2) are coupled by a plurality of tie rods (10, 10, ...) And the movable plate (4) is hydraulically guided by these tie rods. Cylinder·
A mold clamping device which is clamped to the fixed platen (1) by a piston mechanism and is driven by another drive means (20) in a mold clamping direction or a mold opening direction. The hydraulic cylinder-piston mechanism is a cylinder (a cylinder whose end is fixed to the tie rods (10, 10, ...) And the movable plate (4) so as to surround the tie rods (10, 10, ...). , 13), and hydraulic chambers (14, 14, ...) Defined on both sides by piston parts (12, 12, ...) Formed on the tie rods (10, 10, ...). , 15, 15, ...) have the same pressure receiving area, and both the hydraulic chambers (14, 14, ... 1)
, 15) are communicated with each other through a valve mechanism (48) that can be opened and closed, and a mold clamping device of an injection molding machine.