JPH0418815Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Technical Field) The present invention relates to a booster ram type mold clamping device, and particularly to a technique that can advantageously shorten the cycle of a mold clamping process.

(Prior art and its problems) Traditionally, as a type of direct pressure mold clamping device in injection molding machines, tie-casting machines, etc., a movable platen, which is slidably fitted in the main cylinder chamber, is brought close to a fixed platen. - A booster ram having an outer diameter smaller than the outer diameter of the main ram is disposed coaxially within the main ram that is driven in the separating direction, and a booster ram cylinder chamber is formed within the main ram, In the mold clamping operation, pressurized oil is first supplied into the booster ram cylinder chamber to perform the mold closing operation, and then pressure oil is supplied into the main cylinder chamber to perform the mold clamping operation. A so-called booster ram type mold clamping device is known.

By the way, in such a booster ram type mold clamping device, when the mold is closed, pressure oil is not supplied to the main cylinder chamber, so negative pressure is generated in the main cylinder chamber. Usually, the inside of the main cylinder chamber is connected to an external oil tank via a prefill valve, and when the mold is closed, the prefill valve is opened to allow oil to be supplied into the main cylinder chamber. While releasing negative pressure in the main cylinder chamber, during mold clamping operation, the prefill valve is closed to prevent oil from being discharged from the main cylinder chamber, thereby maintaining high pressure in the main cylinder chamber. It's like that.

However, in such a pre-filled valve, in order to ensure high-speed movement of the main ram during mold closing operation, it is necessary to set a sufficiently large flow path area in the open state, so the operating stroke becomes large. The opening/closing operation, that is, when the device moves to the mold clamping operation after the mold is closed, there is a problem in that it takes a relatively long time to switch the prefill valve to the closed state.

Particularly in recent years, when shortening the molding cycle has become a major goal, some kind of solution has been desperately needed.

(Solution) The present invention was developed against the background of the above-mentioned circumstances, and its feature is that the movable plate is slidably fitted into the main cylinder chamber, and the fixed plate is replaced with a fixed plate. A booster ram having a smaller diameter than the main ram is disposed coaxially within the main ram which is driven in a direction toward and away from the main ram, and a booster ram cylinder chamber is formed within the main ram,
Prior to the action of hydraulic pressure on the main ram, the action of hydraulic pressure on the booster ram allows two stages of mold closing speed: a high speed mold closing operation and a low speed mold closing operation before the mold closing is completed following the high speed mold closing operation. The main ram is configured to drive the mold closing, and
A pre-fill valve is provided which releases the negative pressure in the main cylinder chamber when the mold is closed and maintains the high pressure inside the main cylinder chamber when the mold is clamped by controlling the communication state of the main cylinder chamber with the external oil tank. A booster ram type mold clamping device comprising: an operating mechanism for closing the prefill valve when switching from high speed mold closing operation to low speed mold closing operation to isolate the main cylinder chamber from the external oil tank; A flow path is provided that directly connects the main cylinder chamber and the external oil tank to supply oil to the main cylinder chamber, and a flow path is provided on the oil supply flow path for supplying oil to the main cylinder chamber. An auxiliary valve means for controlling the mold is provided, so that oil is directly supplied into the main cylinder chamber from the external oil tank only through the oil supply flow path during the low-speed mold closing operation.

(Examples) Hereinafter, in order to clarify the present invention more specifically, examples of the present invention will be described in detail with reference to the drawings.

First, FIG. 1 shows a booster ram type mold clamping device having a structure according to the present invention. In this figure, a main cylinder 10 supports one end of four tie bars 14 at a flange 12 formed on the outer periphery of the front end side (right side in FIG. 1). A fixed platen 18 equipped with a fixed mold 16 is fixed to the other end of these tie bars 14. Further, a movable platen 22 equipped with a movable mold 20 is attached to the intermediate portion of these tie bars 14, and the movable platen 22
The tie bar 14 supports the fixed plate 18 so that it can be slidably guided toward and away from the fixed plate 18.

Further, on the inner circumferential surface of the main cylinder 10, a main ram 2 is fixed to the movable platen 22 at its front end.
4 is fitted in the large diameter portion 26 at its rear end so as to be slidable in the front-rear direction, that is, in the direction toward and away from the stationary plate 18.
As a result, the main cylinder chamber is partitioned into a mold clamping chamber 28 on the rear side of the large diameter portion 26 and a mold opening chamber 30 on the front side.

Furthermore, in the mold clamping chamber 28 of the main cylinder 10,
A cylindrical pre-filled valve 36 is fitted so as to be slidable in the front-rear direction, and is constantly operated by a compression coil spring 34 interposed between a closing member 32 that closes the rear opening of the main cylinder 10. It is placed in a state where it is biased forward.

A cylindrical booster ram 38 having a diameter smaller than that of the main ram 24 passes through the pre-filled valve 36 with a certain distance between it and the inner peripheral surface thereof. A bottomed hole 40 is disposed coaxially with the central axis and is formed at the rear end of the main ram 24 on the outer peripheral surface of the front end thereof.
It is slidably and liquid-tightly fitted to the inner circumferential surface of the housing in the front-rear direction. That is, as is clear from this, the bottomed hole 40 constitutes the booster ram cylinder chamber 54 of the booster ram 38. In addition, such a booster ram 38
is the closing member 32 on the outer circumferential surface of the rear end.
It is fixed liquid-tightly to the

Furthermore, a control chamber 42 for controlling the movement position of the prefill valve 36 is formed in the outer circumference of the prefill valve 36, and an electromagnetic switching valve 44 is connected to this control chamber 42. has been done.

When the hydraulic pressure from the pilot auxiliary pump 45 is applied to the control chamber 42 by switching the electromagnetic switching valve 44, the prefill valve 36 is activated as shown by the solid line in FIG. The mold clamping chamber 28 is moved to the position (rear end position) where it contacts the closing member 32 against the biasing force of the compression coil spring 34, thereby communicating the mold clamping chamber 28 with the external oil tank 46 through the liquid passage 47. This allows hydraulic oil to be supplied into the mold clamping chamber 28 or discharged from the mold clamping chamber 28, and on the other hand, by switching the electromagnetic switching valve 44, When the inside of the control chamber 42 is communicated with the inside of the external oil tank 46 and discharge of hydraulic oil is allowed, the hydraulic pressure inside the control chamber 42 is released, as shown by the imaginary line in FIG. As shown, the prefill valve 36 moves forward according to the biasing force of the compression coil spring 34, thereby preventing the hydraulic oil in the mold clamping chamber 28 from being discharged.

Further, the internal space of the booster ram 38 is connected to an electromagnetic switching valve 50 through a liquid passage 56, and by switching the electromagnetic switching valve 50, the internal space of the booster ram 38 is connected to the variable displacement pump 52. Alternatively, it can be connected to an external oil tank 46. That is, by switching the electromagnetic switching valve 50,
Hydraulic oil is supplied to and discharged from the booster ram cylinder chamber 54 formed in the bottomed hole 40 of the main ram 24. Also,
A low pressure relief valve 59 is connected to the liquid passage 56 for supplying and discharging hydraulic oil into the booster ram cylinder chamber 54 via an electromagnetic switching valve 57. By switching the electromagnetic switching valve 57, the booster The hydraulic pressure in the ram cylinder chamber 54 can be switched between high pressure and low pressure. In addition, in the figure, 66 is a relief valve for maintaining the hydraulic pressure of the hydraulic oil discharged from the variable displacement pump 52 below a certain value.

Furthermore, the liquid passage 56 connecting the electromagnetic switching valve 50 and the booster ram cylinder chamber 54 includes
The mold clamping chamber 28 is connected through the sequence valve 48, and pressure oil is supplied into the mold clamping chamber 28 through the sequence valve 48 by a variable displacement pump 52. There is. Further, a bypass passage 60 is provided between the mold clamping chamber 28 and the liquid passage 56 in parallel with the sequence valve 48 , and a bypass passage 60 is provided on the bypass passage 60 from the mold clamping chamber 28 to the liquid passage 56 . Check valve 64 and throttle 62 whose direction is the forward direction
is provided.

Furthermore, the mold opening chamber 30 is connected to the electromagnetic switching valve 50 via a liquid passage 58, and the switching operation of the electromagnetic switching valve 50 causes the mold opening chamber 30 to Hydraulic oil is supplied and discharged to and from the booster ram cylinder chamber 54 in the opposite manner, that is, without being carried out simultaneously.

Here, in the booster ram type mold clamping device of this embodiment, the interior of the mold clamping chamber 28 is further provided without passing through the prefill valve 36.
An oil supply channel 68 is provided that communicates directly with the external oil tank 46.

The oil supply channel 68 is provided with a structure that allows hydraulic oil to be supplied from the external oil tank 46 into the mold clamping chamber 28 while preventing the hydraulic oil from being discharged from the mold clamping chamber 28. A check valve 70 whose forward direction is the direction from the external oil tank 46 toward the mold clamping chamber 28 is disposed. As is clear from this, in this embodiment, the check valve 70 constitutes an auxiliary valve means for controlling the supply of hydraulic oil to the mold clamping chamber 28 through the oil supply channel 68. There is.

Next, the mode of operation of the mold clamping device in this embodiment having the above-described structure when closing the mold will be described below.

First, FIG. 2 shows changes in the oil pressure in the mold clamping chamber 28 of the main cylinder 10 and in the booster ram cylinder chamber 54 during the mold closing operation of the mold clamping device. That is, when a mold closing start signal is input to the device at point a in FIG. The switching valve 57 is operated to shut off the liquid passage 56 from the low pressure relief valve 59, and under this condition, the electromagnetic switching valve 50 is switched and the variable displacement pump 52 is connected to the booster ram cylinder chamber 54. You will be forced to do so. As a result, with the capacity of the variable displacement pump 52 increased, the main ram 24 is driven forward at high speed by the pressure of the high-pressure working oil applied to the booster ram cylinder chamber 54. A high-speed mold closing operation is performed. In addition, during such high-speed mold closing operation, as the main ram 24 moves forward, the mold opening chamber 3
0 hydraulic oil will be discharged into the external oil tank 46 through the liquid passage 58.

By the way, when the main ram 24 moves forward as described above, as the main ram 24 moves forward,
The volume inside the mold clamping chamber 28 is increased and negative pressure is generated therein, but in such a mold clamping device, this negative pressure causes the liquid passage 47 and Hydraulic oil is introduced into the mold clamping chamber 28 through the oil supply channel 68, the prefill valve 36, and the check valve 70, respectively.
This allows the negative pressure to be eliminated.

Next, when the main ram 24 is in the high-speed mold closing operation state, when the movable mold 20 reaches just before it comes into contact with the fixed mold 16, that is, at point b in FIG.
In order to protect the molds 16 and 20, a mold closing low speed switching signal is input to the device.
As a result, the capacity of the variable displacement pump 52 is reduced, and the electromagnetic switching valve 57 is switched so that the liquid passage 56 is connected to the low pressure relief valve 5.
9. In this way, the forward drive of the main ram 24 is switched to low speed, and the movable mold 20 is moved to the fixed mold 16 under this low speed forward drive state.
This allows the molds 16, 20 to be protected from the impact by alleviating the impact caused by the contact.

Incidentally, even during such a low-speed mold closing operation, negative pressure will be generated in the mold clamping chamber 28 due to the forward movement of the main ram 24, but normally such a low mold closing speed is different from the above-mentioned high-speed mold closing operation. Since the closing speed is set to 1/10 or less, the negative pressure is sufficiently smaller than that during forward high-speed closing operation. and,
In particular, in the mold clamping device of this embodiment, the total flow path cross section of the prefill valve 36 and the check valve 70 corresponds to the mold clamping chamber 28, which is required during the high-speed mold closing operation. It is set according to the amount of supplied oil, and the flow passage cross section of the check valve 70 alone is
Mold clamping chamber 2 required during low-speed mold closing operation
It is set according to the amount of oil supplied with respect to 8.

Then, the mold closing low speed switching signal is inputted.
At the point b in Fig. 2, at the same time, the prefill valve 3
6 is input, and the electromagnetic switching valve 44 is switched, so that the prefill valve 36 is moved to the front end position by the compression coil spring 34 in parallel with the low-speed mold closing operation as described above. As a result, the liquid passage 47 is closed. Note that due to this operation, the liquid passage 47 is closed before the mold closing operation is completed, but the negative pressure in the mold clamping chamber 28 during the low speed mold closing operation is caused by the hydraulic fluid flowing in through the check valve 70. Therefore, it can be effectively resolved. Further, as is clear from this, the operating mechanism that closes the prefill valve 36 when switching from high-speed mold closing operation to low-speed mold closing operation and isolates the mold clamping chamber 28 from the external oil tank 46 is an electromagnetic mechanism. It is composed of a switching valve 44 and a compression coil spring 34.

In this way, when the mold closing operation by the forward drive of the main ram 24 is completed, that is, at point c in FIG. The mold clamping operation is performed by guiding the
Before that, it is necessary to ensure high pressure retention in the mold clamping chamber 28, specifically, the prefill valve 3 that supplies hydraulic oil to the mold clamping chamber 28 during the mold closing operation.
6 and check valve 70 must be closed.

Here, in the mold clamping device of this embodiment, as described above, the prefill valve 36 is already closed during the low-speed mold closing operation (b to c in FIG. 2).
Since the check valve 70 only needs to be closed, the flow path area of the check valve 70 is sufficiently small compared to the prefill valve 36, as described above. As a result, its actuation stroke can be shortened, advantageously reducing the time required for the closing actuation.

After the check valve 70 has been closed, the electromagnetic switching valve 57 is switched at point d in FIG. 2 to shut off the liquid passage 56 from the low pressure relief valve 59, thereby blocking the booster ram cylinder. When the oil pressure in the chamber 54 exceeds a certain value, the sequence valve 48 is operated to supply hydraulic oil into the mold clamping chamber 28. This allows a large hydraulic pressure to be generated within the main ram 24, and a large mold clamping force that can counteract the injection resin pressure can be applied to the main ram 24.

Therefore, in the mold clamping device having the structure as described above, the check valve 70 (oil supply channel) 68
Compared to a conventional mold clamping device that does not have a This can be extremely effectively shortened, thereby reducing the time required for the mold closing operation (a to a in Figure 2).
Therefore, a reduction in the distance between e and e can be advantageously achieved.

In particular, the great effect of such a mold clamping device is that such shortening does not involve any deterioration in the function or performance of the device, and can be easily realized by simple modification. That's what I'm doing.

Note that when opening the molds 16 and 20 after injection molding, the electromagnetic switching valve 44 is switched to move the prefill valve 36 to the retreat position and reduce the hydraulic pressure in the mold clamping chamber 28. This is done by switching the electromagnetic switching valve 50 to connect the booster ram cylinder chamber 54 to the external oil tank 46 and connecting the variable displacement pump 52 to the mold opening chamber 30.
That is, in this case, the main ram 24 is operated backward by the hydraulic pressure generated in the mold opening chamber 30, and the movable mold 20 is separated from the fixed mold 16. During the mold closing operation, positive pressure is generated in the mold clamping chamber 28 due to the backward movement of the main ram 24, but this positive pressure is caused by the hydraulic oil in the mold clamping chamber 28. is eliminated by being discharged into the external oil tank 46 through the liquid passage 47 via the prefill valve 36.

Note that during this mold opening operation, the oil supply channel 68
The discharge of hydraulic oil from the mold clamping chamber 28 through
This is prevented by the check valve 70, but in this embodiment, as described above, a large flow path area is set for the prefill valve 36, so that the mold opening operation is prevented. There are no negative effects.

Above, one embodiment of the booster ram type mold clamping device having the structure according to the present invention has been described in detail.
This is a literal illustration, and the present invention should not be construed as being limited to this specific example.

For example, in the above embodiment, the prefill valve 36 was integrally provided inside the device, but the present invention is also effective for a booster ram type mold clamping device that is provided with the prefill valve externally. It can be applied to any of the following, and thereby the excellent effects described above can be effectively achieved.

Furthermore, in the embodiment described above, the total flow path cross section of the prefill valve 36 and the check valve 70 is set according to the amount of oil supplied to the mold clamping chamber 28 required during the high-speed mold closing operation, In addition, the cross section of the flow path in the check valve 70 alone has been set according to the amount of oil supplied to the mold clamping chamber 28, which is required during the low-speed mold closing operation, but the set flow cross section is limited. Instead, for example, it is possible to set the same flow path cross section for both valve means and close them simultaneously after the mold closing operation is completed, and by doing so, each flow path cross section, i.e. The operating stroke can be effectively reduced, and the object of the present invention can be achieved.

Further, in the embodiment described above, the check valve 70 was used as the auxiliary valve means, but its structure is not limited, and for example, an electromagnetic switching valve can also be used.

Furthermore, it is also possible to control the opening of such auxiliary valve means when the mold is opened, so that the hydraulic oil in the mold clamping chamber 28 is discharged through the auxiliary valve.

Although not listed in detail, the present invention can be implemented with various changes, modifications, improvements, etc. based on the knowledge of those skilled in the art, and such embodiments do not go beyond the spirit of the present invention. It goes without saying that all of these are included within the scope of the present invention as long as they do not deviate from the above.

(Effects of the invention) As is clear from the above explanation, in the booster ram type mold clamping device structured according to the present invention, as a valve means for controlling supply/discharge of oil to/from the main cylinder chamber, In addition to the prefill valve, auxiliary valve means are provided, so each valve means (prefill valve and auxiliary valve means) required to ensure high-speed movement of the main ram during mold closing operation is The flow path area can be advantageously reduced, and the operating stroke of each valve means, that is, the time required for opening/closing operations can be shortened, and therefore the molding cycle can be shortened. This can be achieved effectively.

In particular, in order to protect the mold, the mold closing speed in such a booster ram type mold clamping device is usually a combination of a high-speed mold closing operation and a subsequent low-pressure operation before mold closing is completed. Since the switching is to be performed in two stages, the total flow area of the prefill valve and the auxiliary valve means is set according to the high-speed mold closing operation, and the flow passage area of the auxiliary valve means is set to the low-speed mold closing operation. By setting accordingly, the flow passage area of the auxiliary valve means is set smaller than the flow passage area of the pre-filled valve,
In addition, by closing the prefill valve when switching from high-speed mold closing operation to low-speed mold closing operation, the time required for closing the valve when switching from mold closing completion to mold clamping operation can be further reduced. This makes it possible to shorten the length even more advantageously.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing a booster ram type mold clamping device which is an embodiment of the present invention, and FIG. 2 is an explanatory diagram of the hydraulic pressure in the booster ram cylinder chamber and mold clamping chamber during mold closing operation of the booster ram type mold clamping device. FIG. 2 is an explanatory diagram (graph) showing temporal changes. 10...Main cylinder, 18...Fixed plate, 22...
...Movable platen, 24...Main ram, 28...Mold clamping chamber, 3
0...Mold opening chamber, 34...Compression coil spring, 36
...Prefill valve, 38...Booster ram,
42...control room, 46...external oil tank, 44,
50, 57...Solenoid switching valve, 47, 56, 5
8...Liquid passage, 52...Variable displacement pump, 54...
...Booster ram cylinder chamber, 68...Oil supply channel, 70...Check valve.

Claims (1)

[Scope of utility model registration request] A booster ram smaller in diameter than the main ram is disposed coaxially within the main ram, which is slidably fitted in the main cylinder chamber and drives the movable platen in the direction of approaching and away from the fixed platen. A booster ram cylinder chamber is formed in the main ram, and prior to the action of hydraulic pressure on the main ram, high-speed mold closing operation and mold closing following the high-speed mold closing operation are performed by the action of oil pressure on the booster ram. The main ram is configured to drive the mold closing at two stages of mold closing speed of the low speed mold closing operation before completion, and the mold closing is performed by controlling the communication state of the main cylinder chamber with the external oil tank. In a booster ram type mold clamping device, the booster ram type mold clamping device is provided with a prefill valve that releases negative pressure in the main cylinder chamber during mold clamping and maintains high pressure in the main cylinder compartment during mold clamping.
An operating mechanism is provided for closing the pre-fill valve when switching from high-speed mold-closing operation to low-speed mold-closing operation to isolate the main cylinder chamber from the external oil tank. and providing a flow path for supplying oil to the main cylinder chamber, and disposing an auxiliary valve means on the oil supply flow path for controlling the supply of oil into the main cylinder chamber, A booster ram type mold clamping device characterized in that during the low-speed mold closing operation, oil is directly supplied into the main cylinder chamber from the external oil tank only through the oil supply channel.