JPH0671711A - Mold clamper for injection molding machine or the like - Google Patents

Abstract

PURPOSE:To shorten a length of a mold clamper for an injection molding machine or the like and to eliminate concentration of a mold clamping force at a center of a moving plate by providing a booster cylinder for retracting the plate in the case of switching the mold and a prefilling valve for opening/ closing a through-hole formed at a piston. CONSTITUTION:A booster cylinder 61 is provided in parallel with a mold clamping cylinder 53 between a coupling plate 50 and a moving plate 57, and plate 57 is moved faster by hydraulic pressure to be operated at oil chambers 62, 63 in the case of advancing, retracting the plate 57. A prefilling valve 58 for opening/closing a through-hole 58 is slidably mounted at an end of the piston 52 of a mold clamping piston 51, and operating oil is moved between oil chambers 54 and 55 at the time of advancing, retracting the plate 57. Thus, a length of an apparatus can be shortened, and a mold clamping force is not concentrated near the center of the plate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold clamping device such as an injection molding machine.

[0002]

2. Description of the Related Art A conventional apparatus will be described with reference to FIG. 3. Reference numeral 1 is a mold clamping cylinder, a main ram 2 is slidably mounted on an inner diameter surface, and a movable metal fixed to the tip end by pressure oil acting on oil chambers 3 and 4. The movable plate 5 for mounting the mold is moved back and forth by a stroke s with respect to a fixed plate for mounting a fixed mold (not shown). Reference numeral 6 is a prefill valve which is provided between the oil tank 7 and the oil chamber 4 and normally closes the communication port 9 between the oil chamber 4 and the oil tank 7 by the spring 8. However, when the mold is clamped, the main ram 2 advances. The pressure oil acts on the valve opening chamber 10 so as to suck a large amount of hydraulic oil from the oil tank 7 into the oil chamber 4 which is in the negative pressure state when the spring 8 moves rightward in the figure, and the pressing force of the spring 8 is exerted. The communication port 9 is opened against the above. A booster ram 11 is provided with a through hole 12 in the axial direction, and pressure oil from the outside is guided to a cylinder 13 in the main ram 2. An extruding cylinder 14 has an extruding pin 16 attached to an extruding plate 15, which is operated by a predetermined distance t when the mold is opened after molding the product so that the molded product in the mold is projected.

Because of the above-mentioned structure, a large amount of hydraulic oil moves back and forth between the oil tank 7 and the mold clamping cylinder 1 during the mold opening / closing operation, so that the cycle is long. Since the prefill valve 6 is attached, and further the extrusion cylinder 14 is attached to the front side, the length L of the entire apparatus is long, and since the mold clamping ram 2 is a double cylinder type, it is complicated and machining of the mold clamping cylinder is required. However, there were drawbacks such as being troublesome.

To eliminate these drawbacks, Japanese Examined Patent Publication No. 55-
The device described in Japanese Patent No. 24986 is known. This device will be described with reference to FIG. 4. A chamber of a cylinder 23 in which pressure rams 22 having rods 20 and 21 of the same diameter attached to the front and back sides are slidably inserted in order to form pressure acting areas on the front and back sides substantially equal to each other. Pressure ram 2 on 24 and 25
2, the medium (oil) in the cylinder 23 is advected through the through hole 26 provided in the pressure ram 22 according to the advance and retreat of the cylinder 23, and the movable die mounting moving plate 27 attached to the tip of the rod 20 is moved forward and backward. When the pressure is raised after the mold is closed, the valve 29 is pressed against the through hole 26 by the cylinder 28 attached to the tip of the rod 21 to close the valve 29, and the pressure oil is applied to the chamber 25.

In this device, the booster device 30 is exposed to the outside of the mold clamping cylinder 23, which facilitates the machining of the mold clamping cylinder 23 as compared with the conventional device, and the hydraulic oil is also supplied between the two chambers 24 and 25 of the cylinder. Although a large amount of hydraulic oil came and went between the oil tank and the mold clamping cylinder,
Since the pressure acting areas on the front and back sides are formed to be almost equal, a rod 21 is attached to the retreating side of the pressure ram 22, and when the moving plate 27 is retreating, the rod 21 moves backward by a stroke s as shown by a chain line. As a result, the length L of the device is still long, and the diameter of the rod 20 is limited to a large diameter due to the relationship with the mold clamping cylinder.
Therefore, there is a disadvantage that the mold clamping force is concentrated near the center of the moving plate 27.

The object of the present invention is to eliminate the above-mentioned drawbacks, the structure is simple, the length of the device can be shortened, and the mold clamping force of an injection molding machine or the like in which the mold clamping force is not concentrated near the center of the moving plate. To provide a device.

[0007]

In order to achieve the above-mentioned object, the present invention is a mold clamping cylinder in which a piston is slidably fitted to an inner diameter surface and a movable plate for mounting a movable mold is attached to one end thereof. A connecting plate which is fixed to a frame or the like perpendicularly to the mold clamping direction so as to face the other end surface of the mold clamping cylinder, one end is fixed to the connecting plate in a cantilever state, and the other free end is the mold. It is inserted into the inner diameter surface of the tightening cylinder with liquid honey,
In addition to dividing the mold clamping cylinder into forward and backward oil chambers,
A mold clamping piston formed with a piston having a through hole that connects both chambers, a boost cylinder provided in parallel with the mold clamping cylinder between a connecting plate and a moving plate, and moving the moving plate forward and backward when opening and closing the mold, The through hole formed in the piston is opened and closed by the pressure oil that is slidably attached to the other end of the mold clamping piston and is guided through the oil passage provided in the mold clamping piston and the hydraulic pressure in the chamber for advancing the mold clamping cylinder. A mold clamping device such as an injection molding machine having a prefill valve.

[0008]

When the mold is opened and closed, the moving plate is moved forward and backward by the boost cylinder, so that the working oil in the mold clamping cylinder is inserted between the forward oil chamber and the backward oil chamber in the cylinder through the through hole provided in the piston. For advancing and for pressurization, the through hole is closed by a prefill valve, and then pressure oil is applied through the advancing oil chamber of the mold clamping cylinder.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. 1 and 2. Reference numeral 50 denotes a connecting plate fixed vertically to a mold (not shown) in the mold clamping direction. Is cantilevered. A piston 52 is formed at the other end, which is the free end of the mold clamping piston, is fluid-tightly attached to the inner diameter surface of the mold clamping cylinder 53, and moves forward in the mold clamping cylinder 54 and in the reverse oil chamber. In addition to 55, the oil chambers 54 and 55 can transfer the working oil in the oil chambers 54 and 55 to each other through a through hole 56 provided in the piston 52. The mold clamping cylinder 53 is slidably fitted to the piston 52 at the other end of the mold clamping piston 51 by a stroke S, and has an end portion on the side opposite to the connecting plate for mounting a movable mold. Since the moving plate 57 is attached, the mold is opened and closed with respect to the fixed plate to which a fixed mold (not shown) is attached.

A prefill valve 5 for opening and closing the through hole 56 is provided on the tip side of the piston 52 of the mold clamping piston 51.
8 is slidably mounted, and the mold clamping piston 51 as shown in FIG. 1 is provided so that the hydraulic oil can flow between the oil chambers 54 and 55 when the moving plate 57 moves forward and backward.
2 is used to open the through hole 56 by the pressure oil acting on the valve chamber 60 formed between the mold clamping piston 51 and the prefill bubble 58 through the oil guide hole 59 provided in the. As shown, the through hole 56 is closed.

A boost cylinder 61 is provided between the connecting plate 50 and the moving plate 57 in parallel with the mold clamping cylinder 53. When the moving plate 57 advances and retracts, an oil chamber 62 is provided. And pressure 63 acting on 63 and 63
The To 57 can move faster.

Reference numeral 64 causes the pressure oil discharged from the variable pump 65 to act on the oil chambers 54 and 55 of the mold clamping cylinder to move the moving plate 57 forward and backward and to increase the pressure after the mold is closed, and at the same time, the prefill valve 58. This is an electromagnetic switching valve that controls the opening and closing of the prefill valve 58 by applying pressure oil to the valve chamber 60 of the above. Reference numeral 66 is an electromagnetic switching valve with a pilot that switches the main sprue 66A by the pilot pressure of the oil discharged from the variable pump 65, and cooperates with the electromagnetic switching valve 67 to move the boost cylinder 61 forward and backward by the pressure oil discharged from the variable pump 68. To control.

Check valves 69 and 70 are provided between the oil chambers 54 and 55 and the tank 71, and when the pilot pressure acts, pressure oil does not pass between the oil chambers 54 and 55 and the tank 71. If possible and the pilot pressure does not work, the line is adapted to be closed.

Reference numeral 72 denotes a cam valve provided in the pilot circuit 73 of the pilot-operated solenoid operated directional control valve 66. When the safety door indicated by a chain line is opened from the illustrated operating position (closed state) (leftward in the figure). Switching from the illustrated lower position to the upper position, pressure oil from the pilot circuit 73 does not act on the main sprue 66A of the pilot operated solenoid operated directional control valve 66, and the main sprue 66A becomes the illustrated intermediate position to move the plate 57. Cannot be moved in the mold clamping direction (to the right in the figure). That is, the mold is not closed so that an object, especially a human, is not caught in the mold.
Reference numeral 74 is a throttle for giving a resistance to the return oil from the boost cylinder 61 so that the moving plate 57 can be advanced at a low speed.

The above-mentioned structure is explained. Next, the operation thereof will be described. At the time of mold clamping, the safety door is closed and the cam valve 72 is at the position shown in the drawing.
When the position, the electromagnetic switching valve with pilot 66 is set to the b position, and the electromagnetic switching valve 67 is set to the a position, the pressure oil discharged from the pump 65 acts on the oil chamber 60, and the prefill valve 58 opens the through hole 56 as illustrated. Upon opening, it acts on the check valve 70, pressure oil from the pump 68 acts on the oil chamber 62 of the boost cylinder 61, and since the boost cylinder 61 has a small diameter,
The moving plate 57 moves forward at a high speed (to the right in the figure), and the pipe connecting the oil chamber 55 and the oil tank 71 has a check valve 69.
Is blocked by the oil chamber 5 of the mold clamping cylinder 53.
5 is compressed, the hydraulic oil in the oil chamber 55 is admitted to the forward oil chamber 54 through the through hole 56, and the hydraulic oil is transferred from the oil tank 71 to the negative pressure oil chamber 54 via the check valve 70. Be sucked.

When the moving die plate 57 approaches the forward limit, the solenoid switch valve 67 is de-energized by a limit switch (not shown) to the intermediate position shown, and the discharge oil of the variable pump 68 is throttled to a small amount. At the same time, the return oil from the oil chamber 63 of the boost cylinder 61 returns to the oil tank 71 only through the throttle 74.
7 moves forward at a low speed, the moving die plate 57 reaches the forward limit, and the mold is closed.

When the solenoid directional control valve 64 is de-excited by the limit switch (not shown) at the forward limit of the moving die plate 57 to the position shown in the figure, the action of the pressure oil on the oil chamber 60 of the prefill valve 58 is stopped. , Prefill valve 5
Reference numeral 8 indicates a check valve 70 as well as closing the through hole 56 by the hydraulic pressure in the oil chamber 54 of the mold clamping cylinder 53 as shown in FIG.
Since no pilot pressure is applied to the oil tank 71, the oil passage to the oil tank 71 is also closed, and the oil chamber 54 is pressurized by the oil discharged from the pump 65 to perform mold clamping.

Next, injection (not shown) is performed, and when the product is molded in the mold, a mold opening process is performed to take out the molded product from the mold. At the time of mold opening, if the moving plate 57 is suddenly retracted while a large mold clamping force is applied, the machine may vibrate due to a shock, or the molded product may crack, so that the mold clamping pressure first drops. Done. That is, the electromagnetic switching valve 64 is in the b position, and the pressure oil in the advance oil chamber 54 of the mold clamping cylinder 53 passes through the electromagnetic switching valve 64 to the oil tank 71, and at the same time, the oil chamber 60 of the prefill valve 58.
Pressure oil acts on the prefill valve 58 to open the through hole 56.

Subsequently, the pilot-operated solenoid operated directional control valve 66 is set to the a position, and the discharge oil of the variable pump 68, which has a small discharge amount, acts on the oil chamber 63 of the boost cylinder 61, and the oil chamber 6
The second pressure oil returns to the oil tank 71 through the electromagnetic switching valve 67 and the throttle 74, and at the same time, the oil chamber 54 of the mold clamping cylinder 53.
Since the hydraulic oil therein flows into the oil chamber 55 through the through hole 56, the moving plate 57 starts to retreat at a low speed. When the moving die plate 57 retracts by a predetermined distance, the electromagnetic switching valve 67
Is in the b position, and the hydraulic oil from the oil chamber 62 flows from the solenoid-operated switching valve with pilot 66a to the solenoid-operated switching valve 67b to the oil chamber 63.
Since it is a differential circuit that acts on the oil chamber 63,
The moving plate moves backward at a high speed due to the pressure oil acting on.

When the moving plate 57 approaches the backward limit,
The electromagnetic switching valve 67 is de-energized to the intermediate position shown, and only a small amount of pressure oil from the pump 68 acts on the oil chamber 63, the moving plate 57 retreats at a low speed, and the mold clamping cycle is completed. To do. Although the operation has been described above, the control hydraulic circuit is not limited to this, and may be another circuit as long as it is a circuit that performs such an opening / closing operation.

[0021]

According to the present invention, since the operation is performed with the above-described structure, the structure is simple and the length of the device can be reduced.
Moreover, since the moving plate is attached to the mold clamping cylinder having a relatively large diameter, the disadvantage that the mold clamping force is concentrated near the center of the moving plate is eliminated.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention when a moving plate is in a backward limit.

FIG. 2 is a view showing an embodiment of the present invention, and is a view when the pressure is raised at the forward limit of the moving plate.

FIG. 3 is a view of a conventional mold clamping device.

FIG. 4 is a view of a mold clamping device showing another conventional example.

[Explanation of symbols]

 50 Connection Plate 51 Mold Clamping Piston 52 Piston 53 Mold Clamping Cylinder 54 Forward Oil Chamber 55 Backward Oil Chamber 56 Through Hole 57 Moving Plate 58 Prefill Valve 61 Boost Cylinder 64 Electromagnetic Switching Valve 65 Variable Pump 66 Electromagnetic Switching Valve with Pilot 67 Electromagnetic switching valve 68 Variable pump 71 Oil tank

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[Procedure amendment]

[Submission date] September 7, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0021

[Correction method] Change

[Correction content]

[0021]

According to the present invention, since the operation is performed with the above-described structure, the structure is simple and the length of the device can be reduced.
Moreover, since the moving plate is attached to the mold clamping cylinder having a relatively large diameter, the disadvantage that the mold clamping force is concentrated near the center of the moving plate is eliminated.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] Brief description of the drawing

[Correction method] Added

[Correction content]

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention when a moving plate is in a backward limit.

FIG. 2 is a view showing an embodiment of the present invention, and is a view when the pressure is raised at the forward limit of the moving plate.

FIG. 3 is a view of a conventional mold clamping device.

FIG. 4 is a view of a mold clamping device showing another conventional example.

[Explanation of reference numerals] 50 connecting plate 51 mold clamping piston 52 piston 53 mold clamping cylinder 54 forward oil chamber 55 backward oil chamber 56 through hole 57 moving plate 58 prefill valve 61 boost cylinder 64 electromagnetic switching valve 65 variable pump 66 pilot Electromagnetic changeover valve 67 Electromagnetic changeover valve 68 Variable pump 71 Oil tank

Claims (1)

[Claims] A piston is slidably fitted to the inner diameter surface, and a mold clamping cylinder with a moving plate for mounting a movable mold attached to one end, and the other end surface of the mold clamping cylinder facing the frame, etc. in the mold clamping direction. A vertically fixed connecting plate and one end fixed to the connecting plate in a cantilevered manner, and the free end at the other end is inserted into the inner diameter surface of the mold clamping cylinder with liquid and moves forward and backward in the mold clamping cylinder. It is divided into an oil chamber and a mold clamping piston that has a piston with a through hole that connects both chambers, and is installed in parallel with the mold clamping cylinder between the connecting plate and the moving plate. A boost cylinder for advancing and retreating, and pressure oil that is slidably attached to the other end of the mold clamping piston and guided through an oil passage provided in the mold clamping piston and oil pressure in the mold clamping cylinder advancing chamber Formed Mold clamping apparatus, such as injection molding machine and having a prefill valve for opening and closing the through hole.