JP2524531Y2 - Mold opening and closing circuit of injection molding machine - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold opening and closing circuit of an injection molding machine, and more particularly to a mold opening and closing circuit of an injection molding machine having a booster ram type mold clamping mechanism.

[0002]

2. Description of the Related Art One of the functions required of a mold clamping mechanism of an injection molding machine is a high-speed opening and closing of a mold for shortening an injection molding cycle. Along with this, the mold is closed at a low speed just before the mold is closed to protect the mold, and the mold is opened at a low speed when the mold is opened from a closed state to protect the molded product. That is, the operation of the movable platen is a high-speed closing
Low-speed mold closing-clamping-low-speed mold opening-high-speed mold opening-low-speed mold opening. These series of operations have been performed by supplying and discharging hydraulic oil to and from a cylinder by a hydraulic circuit as shown in FIG.

In FIG. 4, for example, in the case of high-speed mold closing,
The hydraulic oil in the tank 23 is supplied to the booster ram cylinder chamber by the variable displacement hydraulic pump 22 through the three-position four-way switching valve 21.
Sent to 14. In this state, if you move to low-speed mold closing,
At the same time, the discharge amount of the hydraulic pump 22 decreases rapidly. However, main ram 4 is considerably advanced by inertia (100-150mm)
Therefore, the inside of the booster ram 6 is in a vacuum state. Next, until the low-speed discharge oil amount fills the booster ram 6, FIG.
A stop time of the main ram 4 occurs as shown in the graph, and the mold is closed again thereafter.

[0004] Also, in the case of opening the mold, similarly, when shifting from the high speed mold opening to the low speed mold opening, the auxiliary cylinder chamber is opened.
A vacuum is created in the interior of the main ram 4 and a stop time of the main ram 4 occurs until the hydraulic oil for opening the low speed mold fills the sub-cylinder chamber 13.

[0005]

SUMMARY OF THE INVENTION In order to prevent the main ram from being stopped due to the vacuum state in the booster ram which occurs during the transition from the high speed to the low speed as described above, the discharge amount of the variable displacement hydraulic pump is gradually reduced. This has been addressed by installing an amplifier. However, since this amplifier is very expensive, it has been one of the causes of an increase in the cost of the injection molding machine.

SUMMARY OF THE INVENTION An object of the present invention is to prevent the occurrence of stop time of the main ram and to smoothly accelerate and decelerate the movable plate without using an expensive amplifier.

[0007]

Means for Solving the Problems As means for achieving the above object, the constitution of the present invention is as follows. That is, on one side of the cylinder body, a main ram having a movable plate attached to the tip is slidably mounted, and a booster ram for increasing the speed of the main ram is provided in the cylinder body. A surge valve loosely fitted on the outside is arranged, and a booster ram cylinder chamber formed at the tip of the booster ram and a hydraulic oil tank are connected via a directional control valve and a hydraulic pump. Connecting the sub-cylinder chamber formed in the section and the directional control valve
In the mold opening and closing circuit of an injection molding machine having a configuration described above,
Both the booster ram and each pipe connected to the sub cylinder chamber
Or at least one branch branching from either one
Between the pipe and the tank, the booster ram cylinder or
Supply hydraulic oil from tank according to negative pressure of sub cylinder chamber
A check valve for
You.

[0008]

With the above construction, a vacuum state is generated in the booster ram during the transition from the high-speed closing to the low-speed closing, and a negative pressure is generated in the booster ram cylinder chamber.
When it occurs, it branches off from the piping connected to the booster ram
Since the hydraulic fluid in the tank is introduced into the booster ram via the check valve connected to the branch pipe, a smooth transition is performed without stopping the main ram. Similarly, at the time of transition from the high speed mold opening to the low speed mold opening, when a negative pressure is generated in the sub cylinder chamber, the sub cylinder chamber is connected to the sub cylinder chamber.
Since the hydraulic oil Gashirube enter the tank through a check valve connected to the branch pipe branched from the pipe, smooth transition is carried out without the main ram is stopped. In this way, the transition from high speed to low speed can be performed smoothly without the need to install an amplifier.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings. First, a conventional booster ram type mold clamping mechanism body will be described with reference to FIG. Reference numeral 1 denotes a cylinder main body, which is roughly constituted by an enlarged diameter portion 2 and a reduced diameter portion 3. A main ram 4 is slidably provided in the enlarged diameter portion 2, and a movable plate 5 is attached to a distal end portion of the enlarged diameter portion 2 so as to face a fixed plate (not shown). The main ram 4 is a large diameter portion that contacts the inner peripheral surface of the enlarged diameter portion 2
4a and a small-diameter portion 4b connecting the large-diameter portion 4a and the movable platen 5 to each other.

Along the center line of the cylinder body 1,
A hollow booster ram 6 extending from the rear end of the cylinder body 1 to the center of the main ram 4 is provided. Further, a surge valve 10 having a valve body 9 in contact with a valve seat 8 at the tip of an annular projection 7 provided between the reduced diameter portion 3 and the enlarged diameter portion 2 is provided in the reduced diameter portion 3 of the cylinder body 1. Is provided. The surge valve 10 is urged to be always closed by a spring 11 provided between the surge valve 10 and the left end of the cylinder body 1. The movable platen 5 is provided with a cam 5a.
Is provided with a limit switch LS at a predetermined position, and is configured to emit a signal when the movable platen 5 advances to a predetermined position. Of course, the position of the movable platen 5 can be confirmed by an encoder or the like.

A main cylinder chamber 12 is formed between the large-diameter portion 4a of the main ram 4 and the annular projecting portion 7, and between the large-diameter portion 4a and the right end of the cylinder body 1, that is, of the main ram 4, A sub-cylinder chamber 13 is formed on the outer peripheral portion of the small diameter portion 4b. Further, a booster ram cylinder chamber 14 is formed in the main ram 4 corresponding to the tip of the booster ram 6. A first chamber 15 is formed between the annular projection 7 and a support 3a provided on the reduced diameter portion 3 for slidably supporting the surge valve 10. The first chamber 15 is communicated with the main cylinder chamber 12 when the surge valve 10 is opened. Also, the support part of the surge valve 10
An annular space 16 is provided at the rear end of 3a. further,
A second chamber 17 is formed between the rear end of the surge valve 10 and the closed portion of the cylinder body 1. An annular gap 18 is provided between the booster ram 6 and the surge valve 10, and the gap 18 connects the second chamber 17 and the main cylinder chamber 12.

Next, the control circuit of the main body of the mold clamping mechanism configured as described above will be described again with reference to FIG. The port of the booster ram 6 is connected to a three-position four-way switching valve 21 as a directional control valve, and further connected to a hydraulic oil tank 23 via a variable displacement hydraulic pump 22. The port of the booster ram 6 is a 2-position 3-way switching valve
It is connected to a low pressure relief valve 25 via this valve 24. Between the port of the booster ram 6 and the three-position four-way switching valve 21, a two-position four-way switching valve 26 with a throttle is interposed as a brake valve.

The port of the second chamber 17 is connected to a three-position four-way switching valve 21 via a sequence valve 27 with a throttle / check valve.
It is connected to the. The sub-cylinder chamber 13 is connected to a three-position four-way switching valve 21 via a throttled two-position four-way switching valve 28 as a brake valve. The annular space 16 is connected to a tank and a pilot pressure line (not shown) for always ensuring a predetermined oil pressure through a two-position four-way switching valve 29. To operate the surge valve 10. The operation of the surge valve 10 allows the main cylinder chamber 12 and the first chamber 15 to communicate with each other.
The chamber 15 is always in communication with the hydraulic oil tank. A relief valve 30 is provided between the three-position four-way switching valve 21 and the hydraulic pump 22.

Next, the operation of the mold clamping mechanism configured as described above will be described with reference to the function tables shown in FIGS. First, in high-speed closing, the solenoid c of the three-position four-way switching valve 21 is excited, and hydraulic oil from the hydraulic pump 22 is introduced into the small-capacity booster ram cylinder chamber 14. At this time, 2 position 4
When the solenoid a of the direction switching valve 29 is demagnetized, the surge valve 10 is opened against the urging force of the spring 11 by the pressure oil introduced into the annular space 16. As a result, the main cylinder chamber 12 becomes negative pressure as the main ram 4 advances, and hydraulic oil is supplied from the tank through the first chamber 15 to the main cylinder chamber.
The movable platen 5 moves forward at a high speed.

When the movable platen 5 moves forward at a high speed and the cam 5a pushes the limit switch LS at a predetermined position, the hydraulic pump 22
And the main ram 4 shifts to the low speed type closing. At this time, as described above, the main ram 4 moves forward due to inertia, and a vacuum is generated in the booster ram cylinder chamber 14. To prevent this, the rotation of the hydraulic pump 22 is controlled by the operation of an amplifier (not shown). Appropriate control is performed to smoothly shift the main ram 4 from high speed to low speed. In general, if an amplifier is not used, the flow rate changes too quickly, causing a shock and a phenomenon in which the main ram 4 stops. At this time, the solenoid of the 2-position 4-way switching valve 28 with the throttle is used.
The CB is excited, and the thirteen hydraulic oils are throttled by the throttle of the valve 28 and then returned to the tank 23, so that the valve 28 serves as a brake of the main ram 4.

Next, when a mold (not shown) is closed at a low speed, pressure clamping is performed. That is, when the solenoid a of the two-position four-way switching valve 29 is excited and the pressure oil in the annular space 16 is returned to the tank, the surge valve 10 is rapidly closed by the urging force of the spring 11. Then, after the solenoid b of the two-position three-way switching valve 24 is excited to stop the flow to the low-pressure relief valve 25, high-pressure oil is introduced into the booster ram cylinder chamber 14. When the pressure in the booster ram cylinder chamber 14 reaches a certain pressure, the sequence valve
The operation of 27 causes the high-pressure oil to pass through the second chamber 17 and the gap 18 and is introduced into the main cylinder chamber 12, and the high pressure acts to clamp the mold.

At the next opening of the low-speed mold, the two-position four-way switching valve a is excited and the surge valve 10 is closed.
At the same time, the solenoid o of the 3-position 4-way switching valve 21 is excited.
When magnetized, the solenoid CB of the two-position four-way switching valve 28 is demagnetized, and the hydraulic oil from the hydraulic pump 22 is introduced into the sub-cylinder chamber 13 and acts to retreat the main ram 4. At this time, the solenoid OB of the two-position four-way switching valve 26 is excited as described above, and the valve 26 plays a role of a brake of the main ram 4. Next, after the solenoid OB is demagnetized, the hydraulic oil supply amount of the hydraulic pump 22 is increased, and at the same time, the solenoid a of the two-position four-way switching valve 29 is turned on.
Is excited, the surge valve 10 opens, and the main cylinder chamber 1
2 communicates with the tank, and the retraction of the main ram 4, that is, the mold opening speeds up.

When the main ram 4 reaches a predetermined position, the solenoid a is excited and the surge valve 10 is closed,
At the same time, the solenoid OB of the two-position four-way switching valve 26 is excited, and the low-speed mold opening is performed while the throttled two-position four-way valve 26 performs the braking action as described above. In the transition from the high-speed opening to the low-speed opening, similarly to the transition from the high-speed closing to the low-speed closing, generation of a vacuum state in the sub-cylinder chamber 13 due to inertial movement of the main ram 4 is prevented by the amplifier. .

Next, an embodiment according to the present invention will be described with reference to FIG. In this embodiment, a first branch pipe 31 branched from the middle of the piping between the port of the booster ram 6 and the two-position four-way valve 26 with a throttle is connected to the tank and allows only the flow from the tank to the booster ram 6. The first check valve 32 is provided, and similarly, the tank is connected to a second branch pipe 33 branched from the middle of the pipe between the sub cylinder chamber 13 and the throttled two-position four-way valve 28. The structure is almost the same as the mold clamping mechanism of FIG. 4 except that a second check valve 34 that allows only the flow from the tank to the sub-cylinder chamber 13 is provided. Therefore, the reference numerals assigned to all members of the mold clamping mechanism of the present embodiment are the same as the reference numerals assigned to all members of the conventional mold clamping mechanism, and a description thereof will be omitted.

As described above, the first and second check valves
The operation of the mold clamping mechanism provided with 32 and 34 will be described. First, when shifting from the high speed type closing to the low speed type closing, the booster ram cylinder chamber is formed by the inertia of the main ram 4 as described above.
When a vacuum state is going to be generated in 14, hydraulic oil is introduced from a tank connected to the first branch pipe 31 via the first check valve 32. This makes it possible to prevent the occurrence of a vacuum state in the booster ram cylinder chamber 14, and as shown in the graph of FIG. 3, the stop state of the main ram 4 can be eliminated, and the high-speed type closing to the low-speed type closing can be performed. Can be performed very smoothly.

Similarly, when shifting from the high speed mold opening to the low speed mold opening, if a vacuum state is to be generated in the sub-cylinder chamber 13, the operating oil is supplied from the tank connected to the second branch pipe 33 to the second check valve. Introduced via 34. As a result, the occurrence of a vacuum state can be prevented, and the transition from the high-speed mold opening to the low-speed mold opening can be smoothly performed. Accordingly, by providing these inexpensive check valves, it is possible to eliminate the need for a very expensive amplifier that has been required conventionally.

In the above embodiment, an example in which a variable displacement hydraulic pump is employed has been described. Similarly, even when a fixed hydraulic pump is used, the main ram can be smoothly accelerated and decelerated.

[0023]

[Effects of the present invention] As is clear from the above description, the present invention
According to the figure, the negative pressure in the cylinder chamber
Hydraulic oil from tank is checked for pressure generation
Supply to each cylinder chamber via valve and branch pipe
So they are inexpensive without the need for very expensive amplifiers
Only attaching the valve and piping only, from migration and fast Mold Opening from closing fast type to close the low speed type Ki out to perform the transition to low-speed opening smoothly, injection molding a result, while maintaining a high speed molding Machine cost reduction can be achieved.

[Brief description of the drawings]

FIG. 1 is a schematic circuit diagram for opening and closing a mold of an injection molding machine according to an embodiment of the present invention.

FIG. 2 is a function table of FIG. 1;

FIG. 3 is a graph showing a change in speed when the movable platen shifts from a high speed to a low speed according to the embodiment of the present invention;

FIG. 4 is a schematic circuit diagram for opening and closing a mold of a conventional injection molding machine.

FIG. 5 is a graph showing a change in speed of a conventional movable platen when shifting from a high speed to a low speed.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylinder main body 2 Enlarged diameter part 3 Reduced diameter part 4 Main ram 5 Movable plate 10 Surge valve 12 Main cylinder chamber 13 Sub-cylinder chamber 14 Booster ram cylinder chamber 21 3 position 4 direction switching valve 22 Hydraulic pump 23 Hydraulic oil tank 31 First Branch pipe 32 First check valve 33 Second branch pipe 34 Second check valve

Claims (1)

(57) [Scope of request for utility model registration] 1. A main ram having a movable plate attached to a tip thereof is slidably mounted on one side of a cylinder main body, and a booster ram for increasing the speed of the main ram is provided in the cylinder main body. A surge valve loosely fitted to the outside of the booster ram is provided, and a booster ram cylinder chamber formed at the tip of the booster ram and a hydraulic oil tank are connected via a directional control valve and a hydraulic pump, and a small diameter of the main ram is provided. Mold opening / closing circuit of an injection molding machine having a configuration in which a sub-cylinder chamber formed in an outer peripheral portion of the section is connected to the directional control valve.
In the path, each pipe connected to the booster ram and the sub-cylinder chamber
At least one branching off from both or either
Between the branch pipe and the tank, the booster ram cylinder or
Or the hydraulic oil from the tank according to the negative pressure in the auxiliary cylinder chamber.
A check valve for supply is provided.
Mold opening and closing the circuit of the injection molding machine that.