JPH0976315A - Mold clamping device for injection molding machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure necessary clamping force and clamping speed so as to use for both injection molding and injection compression molding by providing, on a stationary platen, a second clamping cylinder for performing compression molding by moving a movable platen back and forth with respect to the stationary platen. SOLUTION: A movable platen 3 is moved back and forth by a pair of mold opening/closing cylinders 5 arranged on a stationary platen 1 and mold clamping is performed by a single-acting mold clamping cylinder 7. A pair of second mold clamping cylinders 10 which are considerably smaller than the mold clamping cylinder 7 and are nearly the same as the mold opening/closing cylinder 5 are provided in between the front platen 1 and the movable platen 3 in parallel with the mold opening/closing cylinders 5. Molds 2 and 4 are closed up to predetermined positions, a melting resin is injected into a cavity formed by leaving a compression margin, and the compression margin is compressed with pressure by the clamping cylinder 7 and the second clamping cylinders 10 with hydraulic pressure. Although the second mold clamping cylinder 10 is small in size and mold clamping is small, mold clamping can be done at a high speed by that portion, so that small mold clamping force and speed control necessary for compression molding become possible.

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 for an injection molding machine, and more particularly to a mold clamping device that can be used for both ordinary injection molding and injection compression molding.

[0002]

2. Description of the Related Art In the mold clamping operation of a mold clamping device in ordinary injection molding, a movable plate having a movable mold attached thereto is moved to a mold closing position at high speed by a mold opening / closing cylinder, and after the two molds come into contact with each other, Since the clamping force is applied, there is no need for high-speed mold clamping in which a large amount of pressure oil acts instantaneously.However, when compression molding is performed using this mold clamping device, the compression molding does not involve melting molten resin. Since it is injected into the cavity at high speed into a cavity, and is rapidly compressed to be filled and molded at once, it is necessary to instantly apply a large amount of pressure oil to the mold clamping cylinder during compression.

[0003]

Therefore, when a normal mold clamping device for injection molding is used as it is as a mold clamping device for injection compression molding, the mold clamping cylinder is large, so that it is compressed rapidly as described above. In addition to not being able to secure the required mold clamping speed for filling and molding all at once, it also requires a large amount of pressure oil instantaneously, so the capacity of the hydraulic pump must be increased and the capacity of the pump must be increased. There was a problem that the cost for the addition increased. The object of the present invention is a mold that can be used for both normal injection molding and injection compression molding, in which the required mold clamping speed cannot be ensured as described above, and the problem of new cost increase due to increased capacity and addition of pump is solved. To provide a fastening device.

[0004]

As a result of various studies to achieve the above-mentioned object, 1) The mold clamping force at the time of compression may be smaller than the mold clamping force at the time of normal molding. 2) Speed control during compression is very important for molding. Based on the conclusion, the mold opening / closing cylinder provided on the fixed plate to which the fixed mold was attached advances and retracts the movable plate on which the movable mold is attached, and after both molds have abutted, the mold clamping cylinder attached to the movable plate is used to clamp the mold. In the mold clamping device of the injection molding machine that performs
The mold clamping device of the injection molding machine is characterized in that the movable platen is moved back and forth with respect to the fixed platen, and a second mold clamping cylinder for performing compression molding is provided on the fixed platen.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Next, one embodiment of the present invention will be described with reference to FIGS. Reference numeral 1 is a fixed plate to which a fixed mold 2 is attached, 3 is a movable plate to which a movable mold 4 is attached, which is guided by a pair of mold opening / closing cylinders 5 provided on the fixed plate 1 to a tie bar 6 and is fixed to the fixed plate 1. It is designed to move forward and backward. Reference numeral 7 denotes a single-acting mold clamping cylinder for clamping the molds 2 and 4, both molds 2 and 4 contact by the mold opening / closing cylinder 5, and a half nut 8 meshes with a thread groove of a tie bar 6 by a cylinder 9. Then, only when the mold is clamped, pressure oil is introduced into the oil chamber 7a to push the mold clamping ram to the right in the figure so as to spread the space between the half nut 8 and the fixed platen 1 and to open the mold. At this time, the pressure oil acting on the oil chamber 7a is released. Reference numeral 10 is a second mold clamping cylinder that is considerably smaller than the mold clamping cylinder 7 and is approximately the mold opening / closing cylinder 5.
1 between the fixed platen 1 and the movable platen 3 parallel to the mold opening / closing cylinder 5
I have a pair.

Next, the hydraulic circuit of FIG. 3 will be described.
A fixed plate 1 is provided with a pair of mold opening / closing cylinders 5, and a mold closing oil chamber 5a is provided with a pipe line 11. When a mold is closed, a hydraulic pressure source 13 such as a pump is supplied from a hydraulic source 13 such as a pump via a logic valve 12. The pressure oil acts as described above, and the hydraulic oil in the oil chamber 5a is discharged when the mold is opened. Further, a pipe line 14 is provided in the mold opening oil chamber 5b so that the pressure oil from the hydraulic pressure source 13 acts through the logic valve 21 when the mold is opened, and the hydraulic oil in the oil chamber 5b is closed when the mold is closed. The oil is discharged to the oil tank 18 via the logic valve 15, the logic valve 16, or the relief valve 17.

The fixed platen 1 is also provided with a pair of second mold clamping cylinders 10, and the mold clamping side oil chamber 10a and the mold opening side oil chamber 10b are respectively connected via electromagnetic switching valves 19 to pipelines. 1
1 and the oil tank 18 are connected. Logic valves 16 and 21 are provided to control the suction of the pressure oil from the oil tank 18 to the mold opening / closing cylinder 5 so that the movable platen 3 moves at high speed during mold opening / closing (in the present embodiment, There is no suction of this pressure oil).

Reference numeral 22 is a pilot circuit, which is an electromagnetic switching valve 2
3, 24, 25 connected to the same valve, 23, 24, 2
5, the logic valves 12, 15, 16, 20 are switched.
The opening and closing of 21 and 21 are controlled. Numerals 26 to 28 are shuttle valves, which are the logic valve 20 and the logic valve 12 depending on whether the pressure oil is applied from the left or right respectively.
Also, the opening and closing of the logic valve 16 is controlled. Two
Reference numeral 9 denotes a cam valve. When a safety door (not shown) is opened, the cam is pushed to the upper position in the figure to close the mold and close the logic valve 12 which is in a state where pressure oil can pass, and a state where pressure oil cannot pass. This is to prevent the mold from closing. An electromagnetic switching valve 30 controls whether or not pressure oil is applied to the mold clamping cylinder 7 by switching the electromagnetic switching valve.

The structure is as described above. Next, its operation will be described. First, in mold clamping, when the electromagnetic switching valve 23 is in the excited state, the electromagnetic switching valve 24 is in the b position, and the electromagnetic switching valves 19, 25 and 30 are in the non-excited state, the pressure oil in the pilot circuit 22 is the electromagnetic switching valve. It acts on the logic valve 21 via the position 24b, closes the valve 21 and acts from the right side of the shuttle valve 26 in the figure to close the logic valve 20, while the return side of the electromagnetic switching valve 24b is connected to the oil tank 18. Therefore, since the logic valve 15 is in the pressure oil passable state, the electromagnetic switching valve 25 is in the non-excited state, and the shuttle valve 27 is also connected to the oil tank 18 via the electromagnetic switching valve 24b position, the logic valve 12 is The pressure oil can pass through.

Further, since the pressure oil in the pilot circuit 22 acts from the right position of the electromagnetic switching valve 23 to the right side of the shuttle valve 28 to close the logic valve 16, the pressure oil from the hydraulic pressure source 13 passes through the logic valve 12. Mold open / close cylinder 5 from pipe 11
Of the mold closing oil chamber 5a and the mold clamping side oil chamber 10a of the second mold clamping cylinder 10, the working oil in the mold opening oil chamber 5b of the mold opening / closing cylinder 5 is discharged from the pipe line 14, Return to the oil tank 18 via the logic valve 15 in the oil passage state,
Since the working oil in the mold opening side oil chamber 10b of the second mold clamping cylinder 10 is returned to the oil tank 18 from the electromagnetic switching valve 19, the movable platen 3 having the movable mold 4 attached is fixed to the fixed platen 1 side. Move and start moving the mold at low speed.

Subsequently, when the movable platen 3 moves to a predetermined position, the electromagnetic switching valve 23 becomes non-excited by a signal from a signal transmitter (not shown), and the electromagnetic switching valve 24 is moved to the left position shown in FIG. When the electromagnetic switching valve 25 is excited and switched to the left position, pressure oil acts on the shuttle valve 26 via the left position of the electromagnetic switching valve 23, and the logic valve 20 is set to the pressure oil passage impermissible state. Reference numeral 12 communicates with the oil tank 18 through the electromagnetic switching valve 25, and since the pressure oil does not act on the shuttle valve 26, the pressure oil passage state is maintained, and the logic valves 15 and 16 are connected through the electromagnetic switching valve 24. The pressure oil acts to prevent the pressure oil from passing, and the logic valve 21
Since the pressure oil can pass through, a differential circuit is formed between the mold closing oil chamber 5a and the mold opening oil chamber 5b of the mold opening / closing cylinder 5.
The hydraulic oil in the mold opening oil chamber 5b, which has been returned to the oil tank 18 via the logic valve 15 until now, merges into the pipe line 11 via the logic valve 21, and a large amount of pressure oil is transferred to the mold opening / closing cylinder 5. Mold closing oil chamber 5a and mold clamping side oil chamber 1 of the second mold clamping cylinder 10.
The movable platen 3 moves forward (to the right in the figure) at high speed.

When the movable platen 3 moves to a predetermined position, the electromagnetic switching valve 23 is excited again by a signal from a signal transmitter (not shown), the electromagnetic switching valve 24 switches to the b position, and the electromagnetic switching valve moves. 25 is non-excited, that is, the above-mentioned low-speed mold movement.

As described above, the molds 2 and 4 are closed to a predetermined position, a predetermined cavity is formed with the compression margin left, and the molten resin is injected into the cavity from an injection device (not shown) into a ball shape. Then, the electromagnetic switching valve 30 is excited next, and the pressure oil from the hydraulic pressure source 13 acts on the oil chamber 7a of the mold clamping cylinder 7 and also on the second mold clamping cylinder 10, and the compression allowance is set to the above two. Mold clamping cylinders 7 and 1
Press 0 to shrink. At this time, as described above, the second mold clamping cylinder 10 is small and the mold clamping force is small, but the mold clamping can be performed at a higher speed correspondingly, and the small clamping force and speed control necessary for compression molding can be performed.

When the injection process is completed and the mold opening process is started, the electromagnetic switching valve 30 is first deenergized and the electromagnetic switching valve 19 is excited, so that the oil chamber 7a of the mold clamping cylinder 7 and the second mold clamping cylinder 7 are excited. The mold clamping side oil chamber 10a of 10 is connected to the oil tank 18 and the mold clamping pressure is released. Next, when the electromagnetic switching valves 23 and 25 are de-energized and the electromagnetic switching valve 24 is switched to the a position, the pressure oil from the pilot circuit 22 acts from the left side of the shuttle valve 26 via the electromagnetic switching valve 23 left position. , The logic valve 20 is closed, and the logic valve 12 has an electromagnetic switching valve 2
The pressure oil acts through the 4a position and the electromagnetic switching valve 25 right position to prevent passage of the pressure oil, and the logic valves 15 and 16 also cannot pass the pressure oil due to the pressure oil from the position of the electromagnetic switching valve 24a. The pressure oil from 13 pushes open the logic valve 21 and acts on the mold opening oil chamber 5b of the mold opening / closing cylinder 5 through the pipe line 14, while the pressure opening oil chamber 10 of the second mold clamping cylinder 10 opens.
b is sucking the pressure oil from the oil tank 18 via the electromagnetic switching valve 19 in synchronism with the action of the pressure oil on the mold opening oil chamber 5b of the mold opening / closing cylinder 5. At the same time, the mold closing oil chamber 5a of the mold opening / closing cylinder 5 and the mold clamping side oil chamber 10a of the second mold clamping cylinder 10 are formed.
The hydraulic oil in the former is from the pipe line 11 via the relief valve 17,
The latter returns to the oil tank 18 through the electromagnetic switching valve 19, and the working oil in the oil chamber 7a of the mold clamping cylinder 7 returns to the oil tank 18 through the electromagnetic switching valve 30 so that the mold opening is performed at a low speed. Be seen.

When the mold is opened to a predetermined position, the electromagnetic switching valve 25 is excited by a signal from a signal transmitter (not shown), the logic valve 12 is allowed to pass pressure oil, and the mold opening / closing cylinder 5 is opened. A differential circuit is formed between the oil chamber 5b and the mold opening oil chamber 5a.
The hydraulic oil in both cylinders 5 and 10 which has returned to the oil tank 18 via 7 pushes open the logic valve 12 and joins the pipe line 14, and a large amount of pressure oil acts on the oil chambers 5b and 10b. , Mold opening is performed at high speed.

When the movable platen 3 is retracted to the predetermined position (to the left in the figure), the electromagnetic switching valve 25 is de-energized and switched to the right position by a signal from a signal transmitter (not shown), and again the above-mentioned. The mold opening process is completed when the mold is opened at a low speed and retracted to a predetermined position.

[0017]

As described above, in the present invention,
Compact clamping force and speed control required for compression molding can be controlled, and not only the required mold clamping speed, which was used in conventional molding machines used for both injection molding and injection compression molding, cannot be secured, but a large amount of mass Since the pressure oil is required, the problem that the capacity of the hydraulic pump has to be increased, and the problem that the cost of the pump is increased and a new cost is increased have been solved.

[Brief description of drawings]

FIG. 1 is a front view showing an embodiment of the present invention.

FIG. 2 is a side view of FIG. 1 showing a first embodiment of the present invention.

FIG. 3 is a hydraulic circuit diagram showing an embodiment of the present invention.

[Explanation of symbols]

 1 Fixed plate 2 Fixed type 3 Movable plate 4 Movable type 5 Type open / close cylinder 6 Tie bar 7 Mold clamping cylinder 8 Half nut 9 Cylinder 10 Second mold clamping cylinder 11 Pipe line 12 Logic valve 13 Hydraulic power source 14 Pipe line 15 Logic valve 16 Logic valve 17 Relief valve 18 Oil tank 19 Electromagnetic switching valve 20 Logic valve 21 Logic valve 22 Pilot circuit 23 Electromagnetic switching valve 24 Electromagnetic switching valve 25 Electromagnetic switching valve 26 Shuttle valve 27 Shuttle valve 28 Shuttle valve 29 Cam valve 30 Electromagnetic switching valve

Claims (1)

[Claims] 1. A mold clamping cylinder mounted on the movable plate after the movable plate mounted on the movable plate is moved forward and backward by a mold opening and closing cylinder provided on the fixed plate on which the fixed mold is mounted and both molds are brought into contact with each other. In the mold clamping device of the injection molding machine, the movable platen is moved forward and backward relative to the fixed platen, and a second mold clamping cylinder for performing compression molding is provided on the fixed platen. Mold clamping device.