JP2727500B2 - Mold clamping device - Google Patents

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 mold clamping device used for molding synthetic resin or die casting.

[0002]

2. Description of the Related Art There are a booster ram type and an auxiliary cylinder type as direct pressure type mold clamping devices. In the booster ram type, a high-speed mold opening booster ram is inserted into the inner clamping ram from the rear end of the clamping cylinder, and a prefill valve is provided in a rear chamber serving as a clamping-side oil chamber of the clamping cylinder. The auxiliary cylinder type has a structure in which an auxiliary cylinder for opening and closing the high-speed mold is provided outside the mold clamping cylinder instead of the booster ram.

However, in any case, when the mold is opened, the prefill valve is opened, and oil is supplied from the oil tank to the space of the mold clamping cylinder rear chamber generated by the forward movement of the mold clamping ram by suction, and the rear chamber is supplied. Is prevented from becoming negative pressure. The mold is closed by supplying pressure oil to the rear chamber after the prefill valve is closed. When the mold is opened, the prefill valve is opened again and the oil in the rear chamber is returned to the oil tank by the backward movement of the mold ram.

[0004]

The oil suction passage in the rear chamber of the mold clamping cylinder has a large diameter so as to fill the rear chamber which expands with the forward movement of the mold clamping ram with oil by suction. I have. Further, the prefill valve is provided at the boundary with the oil tank connected to the rear chamber, but the valve body for opening and closing the suction passage also necessarily has a large diameter, and the opening and closing device is also large.
In addition, there is a problem that an oil tank for suction must be disposed at the rear of the mold clamping cylinder.

[0005] With respect to such conventional problems, in particular, omission of the suction oil tank, the pressure oil in the mold clamping cylinder is moved forward by the movement of the mold clamping ram without releasing the pressure oil in the mold clamping cylinder to the outside. The problem can be solved by alternately moving the chamber between the chamber and the rear chamber, or by pressing the pressurized side pressure oil into the mold clamping ram when the mold is opened and storing it, and returning it to the mold clamping cylinder when the mold is closed. be able to.

However, in the conventional structure in which the pressurized oil is alternately moved between the front chamber and the rear chamber, Japanese Patent Publication No. 56-2461 is known.
As described in Japanese Patent Application Publication No. 4 (1999) -1994, a disk valve for opening and closing an oil passage provided in a piston and an opening / closing means for the disk valve are required, and a switching valve is required even when pressure oil is moved through a differential circuit. Further, since the mold closing means extends to the rear part of the mold clamping cylinder, the mold clamping device is inevitably configured to be long.

[0007] The structure in which pressurized oil is stored in the mold clamping ram is effective for a single-acting type in which hydraulic pressure is applied to only one direction of the mold clamping ram, as described in Japanese Patent Publication No. 64-2497. However, it is difficult to use it for a double-acting mold clamping ram, and a prefill valve is required for the oil passage provided in the mold clamping ram. Has the problem of becoming

The present invention has been conceived in order to solve the above-mentioned conventional problems. An object of the present invention is to employ an inner ram and a mold closing cylinder in a mold clamping device in which a mold clamping ram double-acts, and By making the inside of the clamping ram a clamping oil chamber, the rear chamber of the clamping cylinder, which has been used as the clamping side, is opened,
Accordingly, it is an object of the present invention to provide a new mold clamping device which eliminates the indispensable suction tank of the rear chamber and the accompanying device.

[0009]

SUMMARY OF THE INVENTION According to the present invention, there is provided a mold clamping cylinder having a mold clamping ram slidably inside and a mold closing cylinder on the outside, and A hollow inner ram inserted into the mold clamping ram and having a base end fixed to the mold clamping cylinder; and a mold oil chamber in the mold clamping ram formed by the inner ram. The prefill valve is housed so as to be openable and closable from the rear, and the prefill valve is resiliently pressed in the valve closing direction to partition the inside of the base end into a front part and a rear part. While the front part is connected to a mold clamping hydraulic path, and the rear chamber of the mold clamping cylinder and the front chamber of the mold closing cylinder are opened, whereby High-speed mold opening and closing and strong mold clamping can be performed.

[0010]

[Operation] In the above configuration, by opening the prefill valve provided in the base end portion of the inner ram, the front chamber of the mold clamping cylinder and the mold oil chamber in the mold ram are communicated by a differential circuit. When pressure oil is supplied to the rear chamber of the mold closing cylinder with the pressure oil resistance of the front chamber removed, the mold closing ram also moves in the mold closing direction by the forward movement of the mold closing rod whose tip is connected to the movable plate together with the mold closing ram. You will move at high speed.

After the mold is closed, the prefill valve is closed,
When pressurized oil is supplied to the inner ram, the pressurized oil acts on the clamping oil chamber, while the pressure oil in the front chamber of the clamping cylinder flows out of the differential circuit to the inside of the clamping ram, and surplus oil flows to the tank side. As a result, strong clamping occurs due to the pressure oil in the clamping oil chamber. After strong mold clamping, the pressure in the mold oil chamber is released, and the pressure oil in the mold oil chamber returns to the front chamber via the differential circuit by opening the prefill valve. When pressurized oil is supplied to the front chamber of the mold clamping cylinder so that oil flows out to the tank side, the mold clamping ram moves backward at high speed, and the mold closing rod also moves backward through the movable plate to move the high-speed mold. Opening occurs.

[0012]

1 shows a mold clamping cylinder 1 having a mold clamping ram 2 slidable inside and a pair of mold closing cylinders 3 and 3 on both outer sides.
Are provided in parallel. Inside of the mold clamping cylinder 1 is a front chamber 5 which becomes a mold oil opening chamber by a piston 4 integrated with the mold clamping ram 2,
The interior of the mold closing cylinder 3 is divided into a front chamber 9 and a rear chamber 10 by a piston 8 integrated with an opening / closing rod 7.

Numeral 11 denotes a hollow inner ram which is inserted through the rear wall of the cylinder from the rear end of the mold clamping cylinder 1 to the front end of the mold clamping ram 2 and has its base end 11a integrated with the cylinder rear wall. The inside of the mold clamping ram is formed in the mold clamping chamber 12.

The inside of the base end 11a of the inner ram 11 is enlarged to have a larger diameter than the others, and the prefill valve 13 is accommodated in the rear end so as to be openable and closable in the axial direction. A spring member 15 inside a cylinder 14 extending to the rear end of the ram 11 constantly presses in the valve closing direction to partition the base end into a front portion 16 and a rear portion 17.

The rear portion 17 communicates with the front chamber 5 of the mold clamping cylinder 1 through a differential circuit 18, and a mold opening hydraulic path 19 for supplying pressure oil to the front chamber 5 to the differential circuit 18, An outlet 21 with a valve 20 is connected. A mold clamping hydraulic path 22 is connected to the front part 16, and a mold closing hydraulic path 23 is connected to the rear chamber 10 of the mold closing cylinder 3. Further, the rear chamber 6 of the mold clamping cylinder 1 and the front chamber 9 of the mold closing cylinder 3 are connected to an oil tank path 24 and open to an oil tank 25. This opening may be in the atmosphere. Note that 2 in the figure
6 is a cylinder circuit for opening and closing the prefill valve 13;
Reference numeral 7 denotes a hydraulic pump, and reference numeral 28 denotes a movable plate, to which the end of the mold closing ram 2 and the mold closing rod 7 are connected.

In the above-described mold clamping device, the pressure receiving area (S ₁ ) of the mold clamping oil chamber 12, the pressure receiving area of the front chamber 5 (S ₂ ) of the mold clamping cylinder 1, and the pressure receiving area of the rear chamber 10 of the mold closing cylinder 3 (S ₁ ) S
₀ ), the outer diameter d ₁ of the inner ram 11 and the outer diameter d of the mold clamping ram 2
_2, when the inner diameter d ₃ of the mold clamping cylinder 1, equation as follows is established.

[0017] _{S 1 = (π / 4)} d 1 2 S 2 = (π / 4) (d 3 2 -d 2 2) S 2 = [1+ (0.05~0.1)] × S 1 S _{0 = (1/2) (S 2} -S 1)

From the above relational expressions, the strong mold clamping force (F ₁ ), the strong mold opening force (F ₂ ), the high speed mold opening force (F ₃ ),
The high-speed closing force (F ₄ ) is obtained as follows. (P) is the hydraulic pressure. _{F 1 = S 1 × P F} 2 = (S 2 -S 1) × P F 3 = (S 2 -S 1) × P F 4 = 2S 0 × P

Next, the operation will be described. High-speed mold closing In the mold opening state shown in FIG. 1, the switching valve V4 provided between the mold opening hydraulic path 19 and the mold closing hydraulic path 23 is switched to the a side as shown in FIG. When the switching valve V1 of 26 is switched to the a side, the pressurized oil from the pump 27 is supplied to the rear chambers 10 and 10 in the mold closing cylinders 3 and 3 to pressurize the piston 8 in the mold closing direction, and the front chamber 9 is closed. The oil is released to the oil tank 25. On the mold clamping cylinder side, the prefill valve 13 opens against the spring pressure, so that the front chamber 5 communicates with the mold oil chamber 12 in the mold clamping ram to receive the pressure oil on the front chamber side. Become.

In the state shown in FIG. 2, the mold closing cylinders 3, 3 move the mold closing rods 7, 7 forward while discharging the oil in the front chamber 9 to the oil tank 25. Thereby, the mold clamping ram 2
Also moves forward through the movable platen 28. With the forward movement, the rear chamber 6 of the mold clamping cylinder 1 has an oil tank 2
The oil released to 5 is supplied by suction. Further, the oil in the front chamber 5 (S ₂ ) of the mold clamping cylinder 1 fills the mold clamping oil chamber 12 (S ₁ ) from the differential circuit 18 to the rear part 17 and further passes through the clearance around the prefill valve 13.

However, the relationship between the pressure receiving areas of both chambers is S ₁ <S ₂
Therefore, surplus oil is generated, but the surplus oil is generated by the logic valve 2 in the outflow passage 21 which is opened by the rising pressure of the differential circuit 18.
From 0, it flows out to the oil tank 25. As a result,
The hydraulic resistance on the forward side is removed, and the negative pressure on the rear side is also prevented, so that the mold closing rods 7, 7 and the mold clamping ram 2 advance at high speed, and high-speed mold closing occurs there.

[0022] In the mold closed state shown in powerful clamping Figure 2, as shown in FIG. 3, the pre-fill valve 13 is switched to the switching valve V ₁ to b-side
Close the rear 17 by, when switching the switching valve V ₂ of the clamping hydraulic passage 22 to side b, pressure oil in the front 16 is supplied from the pump 27 through the check valve V _5. On this occasion,
The other switching valves V ₃ and V ₄ are kept in a neutral state.
As a result, the pressure oil acts on the clamping oil chamber 12 in the clamping ram to generate a clamping force of F ₁ = S ₁ × P, where strong clamping is performed.

In the strong mold clamping state shown in FIG. 3, as shown in FIG.
It performed depressurised by switching the switching valve V ₂ on a side, connecting the switching valve V ₄ the mold opening oil pressure passage 19 is switched to the b-side to the pump 27 side, the mold closing hydraulic passage 23 to the oil tank 25 side and, when switching the pilot changeover valve V ₃ of the logic valve 20 to a side, the logic valve 20 is closed, also by clamping ram 2 supplied to the front chamber 5 of the pressure oil clamping cylinder 1 from the pump 27 is retracted Strong mold opening occurs.

[0024] Fast mold opening this powerful type open after, as shown in FIG. 5, when opening the pre-fill valve 13 is switched to the switching valve V ₁ to the a side, rear part of the clamping hydraulic chamber 12 and a proximal end 17 communicates. At the same time, when the switching valve V ₂ is switched to neutral, the front chamber 5 of the mold clamping cylinder 1 and the mold clamping oil chamber 12 communicate with each other via the differential circuit 18. As a result, the pressure oil in the mold oil chamber 12 is supplied to the differential circuit 18.
, And flows out to the front chamber 5 to remove the hydraulic resistance of the mold clamping chamber 12.

On the other hand, the oil in the rear chamber 6 of the mold clamping cylinder 1 is discharged to the oil tank 25 as the mold ram 2 moves backward. Because of this, there is almost no hydraulic resistance to the backward movement of the mold clamping ram 2, and no negative pressure is generated due to the movement. Therefore, the mold clamping ram 2 receives the pressure supplied to the front chamber 5 of the mold clamping cylinder 1. It retreats at high speed by oil, and high-speed mold opening is performed there.

[0026]

According to the present invention, as described above, the prefill valve is housed in the base end of the inner ram inserted from the rear end of the mold clamping cylinder into the mold clamping ram so as to be freely opened and closed from the rear. The rear part in the base end section defined by the above and the front chamber of the mold clamping cylinder communicate with each other by a differential circuit capable of releasing surplus oil, while the front part is connected to a mold clamping hydraulic path and the inside of the mold clamping ram is Since the rear chamber of the mold clamping cylinder, which was formed in the mold oil chamber and functioned as the mold oil chamber, was opened, the oil suction tank, which was indispensable to prevent negative pressure in the rear chamber when the mold was closed, The auxiliary device can be omitted.

The prefill valve and its opening / closing device are
Since it can be mounted on the fixed inner ram, the structure and installation are simpler than when it is mounted on a mold clamping ram that moves open and close, and the prefill valve itself needs only to be able to open and close the inside of the base end, so it has a smaller diameter than before. Also, it does not protrude long from the mold clamping cylinder, and when the mold is closed, the inside of the mold clamping ram is filled with the pressure oil in the front chamber of the mold clamping cylinder by the differential circuit, preventing the generation of negative pressure, A suction tank for supplying oil into the mold clamping ram is not required, and as a result, the mold clamping device can be simplified and downsized.

Further, since the excess pressure oil on the front chamber side of the mold clamping cylinder is discharged from the differential circuit to the tank in the hydraulic circuit after filling the inside of the mold clamping ram, the excess oil causes a failure in closing the mold. When the mold is opened, the pressure oil in the mold clamping ram is returned to the front chamber from the differential circuit, so the pressure oil supplied to the front chamber for mold opening only needs to be released. Therefore, it has a feature that the mold closing by the mold closing cylinder and the mold opening by the front chamber of the mold closing cylinder can be performed at a high speed.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a mold clamping device according to the present invention when the mold is opened.

FIG. 2 is a longitudinal sectional view when the high-speed mold is closed.

FIG. 3 is a longitudinal sectional view of the same when a strong mold is clamped.

FIG. 4 is a longitudinal sectional view when the strong mold is opened.

FIG. 5 is a longitudinal sectional view when the high-speed mold is opened.

[Explanation of symbols]

 Reference Signs List 1 mold clamping cylinder 2 mold clamping ram 3 mold closing cylinder 5 front chamber of mold closing cylinder 6 rear chamber of mold closing cylinder 7 mold closing rod 9 front chamber of mold closing cylinder 10 rear chamber of mold closing cylinder 11 inner ram 11 inner ram 12 Mold clamping chamber 13 Prefill valve 15 Spring member 16 Front part in base part 17 Rear part in base part 18 Differential circuit

Claims (1)

(57) [Claims] 1. A mold clamping cylinder having a mold clamping ram slidably therein and a mold closing cylinder on the outside, and a base end inserted into the mold clamping ram from a rear end of the mold clamping cylinder. Consists of a hollow inner ram fixed to the mold clamping cylinder, and a mold clamping chamber in the mold ram formed by the inner ram. A prefill valve is housed in the base end of the inner ram so as to be openable and closable from behind. At the same time, the prefill valve is resiliently pressed in the valve closing direction to partition the inside of the base end into a front portion and a rear portion, and the rear portion and the front chamber of the mold clamping cylinder are allowed to discharge excess oil. A mold-clamping device characterized in that a front portion is connected to a mold-clamping hydraulic path while communicating with a circuit, and a rear chamber of the mold-clamp cylinder and a front chamber of the mold-close cylinder are opened.