JPH0433247B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a mold clamping device for pressurizing a mold and maintaining it in a pressurized state, such as a mold clamping device for a rotary injection molding machine.

(Prior Art) Rotary injection molding machines are widely used as molding machines for rubber, plastic, etc. This rotary injection molding machine sequentially rotates a plurality of molds and a corresponding number of mold clamping devices at fixed angles and transfers them to a predetermined injection station. While plasticized rubber, plastic, or other materials are injected into the machine, the mold is opened at another station and the molded product is taken out.

In conventional rotary injection molding machines, each mold clamping device is operated by its own hydraulic cylinder, and hydraulic pressure generated by an external hydraulic source is supplied to these mold clamping devices. By doing so, each mold clamping device was activated. FIG. 5 shows an example. 100 in the figure
is a hydraulic cylinder having oil chambers 102 and 104 separated by a piston 101, and a flow path 106.
When hydraulic oil is supplied to the oil chamber 102 through the
and conversely through the flow path 114 to the oil chamber 10.
4 is supplied with hydraulic oil, the ram 108 is lowered to separate the lower mold 110 from the upper mold 112. Therefore, a solenoid valve 11 is provided on the flow paths 106 and 114.
6 is provided, and the supply of hydraulic pressure generated by a hydraulic power source (hydraulic pump) to the oil chamber 102 or 104 or the discharge from the oil chamber 102 or 104 is controlled. Note that 118 is a check valve provided in the flow path 106.

(Problems to be Solved by the Invention) As described above, in the conventional rotary injection molding machine, each mold is equipped with a drive device (hydraulic cylinder 100), and this drive device directly clamps the mold. The structure is such that force is generated and the mold is held in a clamped state.

Therefore, in this rotary injection molding machine, the hydraulic cylinders and hydraulic pumps of each moving mold clamping device must be kept connected at all times, and hydraulic pressure must be supplied and shut off to each mold clamping device. This requires hydraulic equipment such as rotary joints and solenoid valves, and the hydraulic piping becomes complicated, causing problems such as oil leakage.

In addition, conventional rotary injection molding machines require a large amount of force to close the mold, which requires large hydraulic cylinders and hydraulic pumps, making the entire machine bulky. There was a problem.

(Means for solving the problems) The mold clamping device of the present invention has been devised to solve the above problems, and its gist is (A)
An external drive device, (B) (a) mold clamping frame, (b) first and second oil chambers provided independently in the frame, and (c) communication between these oil chambers. (d) a communication path provided independently and separated from the external drive device; (d) provided facing the first oil chamber and separated from the pushing member of the external drive device, the tip of which is connected to the frame; (e) a first ram that is caused to protrude outward and the protruding portion is pushed by a pushing member of the external drive device and pushed into the first oil chamber; and (e) a first ram that faces the second oil chamber. a second ram having a larger pressure-receiving area than the first ram, which is disposed and pushed by the hydraulic pressure of the second oil chamber to clamp the mold; and (C) a mold clamping mechanism provided on the communication path. Under normal conditions, the hydraulic oil flows only from the first oil chamber side to the second oil chamber side, but when a pilot operation force is applied, the valve opens to allow flow in the opposite direction. The mold clamping holding mechanism includes a valve means.

(Operation and Effects of the Invention) As described above, in the mold clamping device of the present invention, a mold clamping mechanism is provided for each mold, and this mold clamping mechanism is separated from the external drive device, and the mold clamping mechanism is driven by the drive device. Driving force is applied to the first ram of. Then, the first ram is pushed into the first oil chamber and generates hydraulic pressure. This oil pressure is transmitted to the second oil chamber through the communication path, and the second ram is pushed based on this oil pressure to tighten the mold. Since the second ram has a larger pressure-receiving area than the first ram, the driving force applied to the first ram is doubled by the second ram, tightening the mold with a strong force.

On the other hand, the operation for releasing the pressurizing force when opening the mold does not require external power, and can be easily performed by supplying a pilot operating force to the unidirectional valve means.

As described above, in the mold clamping device of the present invention, the mold clamping mechanism and the external drive device are provided in a separated state.

Therefore, when the present invention is applied as a mold clamping device for a rotary injection molding machine, a conventional device, that is, a mold clamping device including a drive device is provided for each mold, and these mold clamping devices are connected to external hydraulic pressure such as a hydraulic pump. Unlike devices that rotate and move while connected to a source,
Hydraulic equipment such as rotary joints for connecting pipes and solenoid valves to control supply and cutoff of hydraulic pressure is no longer required, and the problem of oil leakage in these parts can also be resolved.

In addition, each mold clamping mechanism is separated from the external drive device, so only one external drive device is required.
The device configuration becomes simple.

Furthermore, since the mold clamping mechanism is equipped with a mechanism that doubles the applied driving force, it is possible to generate the necessary mold clamping force with a small driving force.

Therefore, a small external drive device can be used, and together with the above effects, equipment costs can be dramatically reduced, and productivity per unit area can be greatly improved.

In addition, after the mold is clamped, the clamping holding mechanism operates to hold the mold in the clamped state, so there is no need to continue applying driving force during this period, and energy can be saved.

As is clear from the above description, the present invention is highly effective when applied to a mold clamping device for a transfer type molding machine such as a rotary injection molding machine.

(Example) Next, an example in which the present invention is applied to a mold clamping device of a rotary injection molding machine for rubber molding will be described in detail based on the drawings.

In FIG. 4, reference numeral 10 denotes the mold clamping mechanism, which is rotated and transferred by a rotary table 12. Reference numeral 15 denotes a frame fixedly provided on the mold clamping station, and a hydraulic cylinder 42 serving as an external drive device is disposed at the bottom of the frame. Further, a pressure receiving part 17 is provided in the upper part, and a spacer block 1 is provided between this pressure receiving part 17 and the mold clamping mechanism 10.
9 is inserted by a cylinder so that it can receive pressure from below.

1 to 3 show the mold clamping mechanism 10 in different operating states. In these figures, the mold clamping mechanism 10 has a frame 14, and an upper mold 16 is held at the upper end of the frame 14. Incidentally, this upper mold 16 is heated by a heating plate 17.

The mold clamping mechanism 10 has a cylindrical portion 18 at its lower part. A piston 22 of a first ram 20 is slidably fitted inside the cylindrical portion 18 . The first ram 20 has an oil chamber (first oil chamber) 24 inside the cylindrical portion 18.
It is for pressurizing the hydraulic oil inside, and the lower part thereof is made to protrude downward from the rotary table 12.

This cylindrical portion 18 has a bottomed cylindrical second ram 2.
6 is fitted downward, and this second ram 26
A second oil chamber 28 is formed by the cylindrical portion 18 and the cylindrical portion 18 . By introducing the hydraulic oil into the second oil chamber 28, the second ram 26 is raised, thereby pressing the lower mold 30 thereon against the upper mold 16. Note that the lower mold 30 is heated by a heating plate 32.

The second oil chamber 28 and the first oil chamber 24 are communicated with each other by a communication passage 34, and the first oil chamber 24
The hydraulic oil is led to the second oil chamber 28. Further, a mold clamping holding mechanism 36 is provided on this communication path 34, and the hydraulic pressure generated in the second oil chamber 28 is held by this mold clamping holding mechanism 36. The mold clamping holding mechanism 36 includes a unidirectional pilot-operated check valve 38 and a relief valve 40, which are provided in parallel with each other. The check valve 38 normally allows hydraulic oil to flow only from the first oil chamber 24 side to the second oil chamber 28 side and prevents flow in the opposite direction, and when pilot operating force is supplied from the outside. Open the valve to allow flow in the opposite direction. In this example, this check valve is operated by electromagnetic force (external operating force). Here, the pilot operating force can be provided to the check valve 38 using an electric signal using a power source provided on the rotary table 12 or the like. On the other hand, when the pressure in the second oil chamber 28 is about to rise above a certain level, the relief valve 40 opens the valve and releases some of the hydraulic oil to the first oil chamber 24, thereby reducing the pressure in the second oil chamber 28. It maintains a constant pressure, and serves as both a mold clamping force setting device and a safety device.

The hydraulic cylinder 42 of the external drive device is the ram 4
4, and as the ram 44 rises, the first ram 20 of the mold clamping mechanism 10 is pushed up.

Next, the operation of the apparatus of this example will be explained.

The injection molding machine of this example sequentially rotates the rotary table 12 by a fixed angle, while the injection device injects and fills the molds 16 and 30 in a clamped state with rubber material, and then fills the molds 16 and 30 with the rubber material. The mold is held in a clamped state for a certain period of time and then opened.
After the molded product is removed, the opened molds 16 and 30 are clamped again and transported to an injection station by an injection device. FIG. 1 shows a state in which the upper mold 16 and lower mold 30 as the molding molds are opened.
The first ram 20 and the second ram 26 are in a lowered state. In this state, when the mold clamping mechanism 10 reaches a predetermined mold clamping station due to the rotation of the rotary table 12, the hydraulic cylinder 42 disposed below the rotary table 12 is activated to raise the ram 44. Then, the first ram 20 is pushed upward, and the hydraulic oil in the first oil chamber 24 is transferred to the second oil chamber 2 through the communication passage 34 and the check valve 38 provided in the middle thereof.
8. As a result, the second ram 26 is pushed to raise the lower mold 30 and press the lower mold 30 against the upper mold 16 under the constant oil pressure (set oil pressure) generated in the second oil chamber 28 . FIG. 2 shows this state. The pressure receiving area of the second ram 26 is the same as that of the first ram 20.
Since it is wider than that of the first ram 20
The applied driving force is multiplied by the second ram 26, and as a result, the molds 16, 30 are clamped with a strong force. Here, the injection device injects the rubber material, and the mold clamping holding mechanism 36
By the action of the check valve 38, the hydraulic pressure generated in the second oil chamber 28 is maintained even after the ram 44 in the hydraulic cylinder 42 is lowered, and the mold clamping state is maintained (FIG. 3). Therefore, the molds 16 and 30 in the clamped state are
The spacer block 19 is moved to the fourth position by the drive cylinder.
After being evacuated from the position shown in the figure to the retreat position,
The mold is transported to a predetermined mold opening station by rotation of the rotary table 12. And in the meantime, mold 1
The molds 6 and 30 are kept in a closed state, and the injected rubber material is vulcanized. When the molds 16 and 30 reach the mold opening station, the mold clamping force is released there, and the molded product is demolded at the mold opening station or at a subsequent product removal station provided separately.

The molds 16 and 30 are opened in the following manner. That is, when the molds 16, 30 reach the mold opening station, a pilot operating force is applied to the check valve 38, which causes the check valve 38 to open. Then, based on the held oil pressure, the oil pressure in the second oil chamber 28 escapes to the first oil chamber 24, the first ram 20 is pushed down, and the pressurizing force is released. At the same time, the lower mold 30 is forcibly lowered together with the second ram 26 by the pressing force of the mold opening pin 46, and the mold is opened.

Incidentally, this mold opening can be easily carried out at any time and at any station, simply by operating the check valve, if necessary.

Now, the molds 16, 30 from which the molded product has been taken out are brought again to the original mold clamping/injection station shown in FIG. 1 by the rotation of the table 12, where mold clamping and injection of the rubber material are performed again. Since a plurality of molds 16, 30 and mold clamping mechanisms 10 are arranged at predetermined intervals on the rotary table 12, a series of these operations is performed one after another for each mold clamping mechanism 10, thereby completing injection molding of rubber. is performed continuously.

The mold clamping device of this example has the advantage that the mold clamping force can be easily set using the relief valve 40.

Although the embodiments of the present invention have been described in detail above, the present invention can also be configured in other forms.

For example, in the above embodiment, the one-way check valve 3
8 is operated by electromagnetic force, but it is also possible to operate it by hydraulic pressure. In this case, the hydraulic pressure for operation can be supplied to the check valve 38 by a small hydraulic pump provided on the rotary table 12.

It is also possible to replace the drive device that drives the first ram of the mold clamping mechanism with a device other than the above-mentioned hydraulic cylinder, and the second ram can be in the form of a plunger that fits into the inner surface of the cylinder. is also possible.

In addition, the present invention can be applied to a mold clamping device for a rotary injection molding machine for plastics, and can also be applied to a transfer type injection molding machine or a press-fit molding machine other than the rotary injection molding machine, and even in some cases. Therefore, it is also possible to apply it to a mold clamping device of an ordinary molding machine that is not a transfer type.

[Brief explanation of drawings]

1, 2 and 3 are diagrams schematically showing a mold clamping device of a rotary injection molding machine according to an embodiment of the present invention in different operating states, and FIG.
The figure is a front (partially sectional) view of the main part showing a part of the rotary injection molding machine, and Figure 5 is a simplified diagram shown to explain a problem with the mold clamping device in a conventional rotary injection molding machine. be. 10... mold clamping mechanism, 20... first ram, 24...
...First oil chamber, 26...Second ram, 28...Second oil chamber, 34...Communication passage, 36...Mold clamping holding mechanism, 3
8... Pilot operated check valve, 40... Relief valve, 42... Hydraulic cylinder.

Claims (1)

[Claims] 1. (A) an external drive device, (B) (a) a mold clamping frame, and (b) first and second oil chambers independently provided in the frame. , (c) a communication passage that connects these oil chambers and is provided independently and separated from the external drive device, and (d) a communication path that faces the first oil chamber and is separated from the pushing member of the external drive device. a first ram, which is provided with a distal end protruding from the frame body, and is pushed into the first oil chamber when the protruding portion is pushed by a pushing member of the external drive device; (e) a mold clamping device that is arranged facing the second oil chamber, is pushed by the hydraulic pressure of the second oil chamber to clamp the mold, and has a larger pressure receiving area than the first ram; and (C) a mechanism provided on the communication passage, which normally allows hydraulic oil to flow only from the first oil chamber side to the second oil chamber side, but when a pilot operating force is applied,
1. A mold clamping device for a molding mold, comprising a mold clamping holding mechanism including a unidirectional valve means that opens the valve and allows flow in the opposite direction.