JP2004195880A - Air evacuation mechanism for mold clamping cylinder and air evacuating method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently evacuate air by carrying out the optionally timely evacuation of air from a hydraulic oil of a mold clamping cylinder. <P>SOLUTION: This air evacuation mechanism is equipped with a mold clamping side oil chamber 7 whose capacity is increased/decreased by moving a ram 8 together with a movable platen 5 by a mold opening/closing means and a surge valve 20 connecting the mold clamping side oil chamber 7 with a tank 21. In addition, the mechanism comprises a mold clamping cylinder 6 which clamps a mold by supplying the hydraulic oil to the oil chamber 7, an air venting valve consisting of a solenoid changeover valve 26 which is connected with the top of the oil chamber 7 and opened/closed by a signal and a control means 27 which sends a signal to the air venting valve in an optionally timely manner. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an air bleeding mechanism and a method for bleeding air from hydraulic oil in a mold clamping side oil chamber in a mold clamping cylinder.
[0002]
[Prior art]
Conventionally, the mold clamping ram fixed to the movable platen by the booster ram can be moved in the mold closing direction, and the mold clamping side oil chamber of the mold clamping cylinder is provided with a surge valve communicating with the tank and an air release valve respectively. As a tightening cylinder, the one described in Patent Document 1 is known.
[0003]
[Patent Document 1]
JP-A-2000-167893 (pages 1 to 4)
[0004]
However, in the device described in Patent Document 1, the air bleed valve is opened and air bleeding is performed only when the hydraulic pressure of the hydraulic oil falls within a predetermined range of cracking pressure. Therefore, when the hydraulic pressure of the operating oil is within the above-mentioned predetermined range at the time of pressure increase and pressure release, the air release valve is opened, and the air release cannot be performed at any time. In addition, there is a problem that the hydraulic pressure of the hydraulic oil is lost because the air is vented even when the pressure is increased.
[0005]
Patent Literature 2 discloses that hydraulic oil is pressure-fed from a drive-side hydraulic cylinder mechanism to a working-side hydraulic cylinder mechanism, and residual air of the working-side hydraulic cylinder mechanism is discharged from an air bleed valve.
[Patent Document 2]
JP 2001-355605 A (page 1, page 7 to page 9)
[0006]
However, the one described in Patent Document 2 communicates the drive side hydraulic cylinder mechanism and the working side hydraulic cylinder mechanism at the time of bleeding air, and when the pressure of the working oil of the working side hydraulic cylinder is increased, The bleed valve was opened, and the structure and operating method were complicated. Further, an air bleed valve operating at a predetermined pressure or lower is used as an air bleeding mechanism, and air bleeding cannot be performed completely at any time.
[0007]
[Problems to be solved by the invention]
An object of the present invention is to perform efficient air bleeding by performing air bleeding from hydraulic oil of a mold clamping cylinder at an arbitrary timing.
[0008]
[Means for Solving the Problems]
The air releasing mechanism for a mold clamping cylinder according to claim 1 of the present invention is connected to a mold clamping cylinder that performs mold clamping by supplying hydraulic oil to the mold clamping side oil chamber and an upper part of the mold clamping side oil chamber. And a control means for sending a signal to the air release valve at an arbitrary timing.
[0009]
Therefore, the air in the mold clamping cylinder can be reliably released from the upper portion of the mold clamping side oil chamber at an arbitrary timing.
[0010]
According to a second aspect of the present invention, there is provided an air bleeding mechanism for a mold clamping cylinder according to the first aspect, wherein the hydraulic mechanism for supplying hydraulic oil to the mold clamping cylinder is provided with a servo valve.
[0011]
Therefore, when performing high-precision hydraulic control by the servo valve, it is possible to remove air entrapment in the mold clamping cylinder, which is a particular obstacle.
[0012]
According to a third aspect of the present invention, there is provided an air release mechanism for a mold-clamping cylinder. And a surge valve connecting the mold-side oil chamber and the tank, and the air release valve is an electromagnetic switching valve connected to an upper part of the surge valve connection position in the mold-side oil chamber. .
[0013]
Therefore, as the ram moves, the volume of the mold-clamping-side oil chamber in the mold-clamping cylinder increases and decreases. The operation can be performed at an arbitrary timing from the upper part of the mold-clamping-side oil chamber.
[0014]
According to a fourth aspect of the present invention, there is provided an air bleeding mechanism for a mold clamping cylinder according to any one of the first to third aspects, wherein a concave portion is provided in a rear upper part of a stroke of a ram of a mold clamping side oil chamber in the mold clamping cylinder. The air vent valve is formed and connected to the recess.
[0015]
Therefore, since the air is accumulated in the concave portion due to the difference in the specific gravity between the hydraulic oil and the air, the air can be reliably removed from the air release valve connected to the concave portion.
[0016]
According to a fifth aspect of the present invention, there is provided a method for releasing air from a mold-clamping cylinder, wherein the mold-clamping cylinder which performs mold-clamping by supplying hydraulic oil to the mold-clamp-side oil chamber is connected to an upper portion of the mold-clamping-side oil chamber. An air bleeding mechanism for the mold clamping cylinder consisting of an air bleeding valve opened and closed by a signal and a control means for sending a signal to the air bleeding valve is provided. A signal is sent from the means to switch the air release valve from the closed state to the open state, and the air release of the hydraulic oil in the mold-side oil chamber in the mold-clamping cylinder is started.
[0017]
Therefore, air bleeding in the mold clamping cylinder can be automatically started from the upper part of the mold clamping side oil chamber and automatically only during the pressure relief before the mold is opened in the molding cycle. Therefore, unlike the case where the air is released by the cracking pressure, the air is not released at the time of increasing the pressure, and the work of setting the cracking pressure is not required.
[0018]
According to a sixth aspect of the present invention, there is provided a method for releasing air from a mold clamping cylinder, wherein the ram is moved together with the movable plate by the mold opening / closing means to increase or decrease the volume, and the hydraulic oil is supplied and the volume is increased at the time of mold clamping, whereby the volume is increased. A clamping cylinder having a chamber, a surge valve connecting the clamping side oil chamber and the tank, an air release valve connected to the top of the mold side oil chamber and opened / closed by a signal, and control to send a signal to the air release valve Means are provided, during the maintenance work of the mold, the surge valve is closed at the mold opening completion position at the time of the molding cycle and a signal is sent from the control means to open the electromagnetic switching type air release valve,
The ram and movable platen are retracted again to the retreat limit position or the vicinity of the retreat limit position by the mold opening / closing means, and the air in the mold-clamping cylinder oil chamber in the mold-clamping cylinder is vented.
[0019]
Therefore, even when the ram and the movable platen are retracted from the mold opening completion position during the maintenance work of the mold, air can be released from the mold clamping side oil chamber in the mold clamping cylinder. Then, before the mold maintenance work, if air has been mixed into the hydraulic oil in the mold-clamping oil chamber when the mold has been stopped at the mold-opening completion position for a certain period of time or more, the air in the mold-clamping-side oil chamber must be vented. It is possible to perform high-precision mold clamping control at the next mold clamping.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described with reference to FIG. FIG. 1 is a diagram showing a mold clamping cylinder and an air release mechanism of the present invention. In FIG. 1, a fixed plate 1 is fixed to a base 2, and four tie bars 4 are disposed between the fixed plate 1 and a pressure receiving plate 3 disposed opposite to the fixed plate 1. The board 5 is movably arranged. A mold clamping cylinder 6 is fixed to the pressure receiving plate 3. Inside the mold clamping cylinder 6, one end 8 a is fixed to the movable platen 5, and the ram 8 slidably inserted through the inner periphery of the mold clamping cylinder 6 by the sliding portion 8 b is movable in the mold opening and closing direction. Is provided. A mold clamping side oil chamber 7 is formed in a space surrounded by the sliding portion 8 b of the ram 8 and the rear side of the mold clamping cylinder 6. A mold-opening-side oil chamber 9 is also formed between the front side of the sliding portion 8 b of the ram 8 and the mold clamping cylinder 6. When hydraulic oil is supplied to the mold-opening-side oil chamber 9, the ram 8 and the movable platen 5 move at a relatively high speed in the mold-opening direction, and the volume of the mold-clamping-side oil chamber 7 in the mold-clamping cylinder 6 decreases. It is being reduced.
[0021]
A booster cylinder 10 having a relatively small diameter is inserted inside the ram 8 of the mold clamping cylinder 6. When hydraulic oil is supplied to the oil chamber 11 of the booster cylinder 10, the ram 8 and the movable platen 5 move at a relatively high speed in the mold closing direction, and the volume of the mold-clamping-side oil chamber 7 in the mold-clamping cylinder 6 is increased. Is to be increased. Therefore, in this embodiment, the mold opening / closing means is constituted by the mold opening side oil chamber 9 of the mold clamping cylinder 6 and the booster cylinder 10. In the present invention, the mold opening / closing means may be one using a side cylinder different from the mold clamping cylinder, or one using an electric motor.
[0022]
Next, the hydraulic mechanism of the mold clamping cylinder 6 will be described. The hydraulic mechanism is provided with a hydraulic pump 12 which is a supply source for supplying hydraulic oil to the mold clamping cylinder 6. A servo valve 14 is provided in the middle of a pipeline 13 from the hydraulic pump 12 to the mold clamping cylinder 6. A pipe 15 is connected to the A port of the servo valve 14, and a pipe 16 is connected to the B port toward the mold opening side oil chamber 9. An electromagnetic directional switching valve 17 is disposed in the conduit 15 connected to the A port, and a conduit 18 is connected to the A port of the electromagnetic directional switching valve 17 toward the booster cylinder 10. A pipe 19 is connected to the port toward the mold-clamping-side oil chamber 7 of the mold-clamping cylinder 6.
[0023]
In this embodiment, a surge valve 20 is provided below the mold-clamping-side oil chamber 7 in the mold-clamping cylinder 6. The surge valve 20 is also called a prefill valve, and is disposed in a large-diameter pipe 22 that connects between the mold clamping cylinder 6 and the tank 21. The surge valve 20 is opened and closed by a pilot pressure when a normally-closed electromagnetic switching valve 23 is excited, so that a large amount of hydraulic oil can be supplied / discharged from the tank 21 into the mold-side oil chamber 7 in a short time. . In this embodiment, the connection position of the surge valve 20 is at the lower part of the mold-side oil chamber 7, but may be at the rear side of the mold-side oil chamber 7.
[0024]
Further, in this embodiment, a concave portion 24 is formed in an upper part of the inner circumference of the mold clamping cylinder 6 above and behind the stroke of the ram 8 of the mold clamping side oil chamber 7 in the mold clamping cylinder 6. The concave portion 24 is located at the uppermost position in the vicinity of the surge valve 20 in the mold-clamping-side oil chamber 7 of the mold-clamping cylinder 6, and operates when air is mixed into the hydraulic oil in the mold-clamping-side oil chamber 7. The recess 24 is formed so that air accumulates in the recess 24 due to the difference in specific gravity between oil and air. The conduit 19 connected to the B port of the electromagnetic direction switching valve 17 is connected to the concave portion 24 of the mold clamping cylinder 6. Further, an air vent pipe 25 is formed, which is mainly branched from the pipe 19 to return the hydraulic oil mixed with air at the time of air release to the tank 21. A normally closed electromagnetic open / close valve 26, which is a valve, is provided and connected to the mold-clamping-side oil chamber 7. Regarding the position of the air release valve, an electromagnetic opening / closing valve 26 may be connected directly to the mold clamping cylinder 6 without passing through the air release line 25, and the air release line 25 may be directly connected to the mold clamping cylinder 6. You may let it. However, it is necessary to provide the servo valve 14 on the mold clamping side oil chamber 7 side. Regarding the type of the air release valve, a normally open electromagnetic opening / closing valve or an electromagnetic direction switching valve may be used, and the air release valve may be opened / closed by a pilot pressure signal based on a signal from the control means.
[0025]
The tank 21 is known, but an air breather (not shown) is attached to the upper part of the tank 21 so that when the oil level in the tank 21 rises due to the hydraulic oil refluxed to the tank 21, the air is released from the tank 21. Is discharged to the outside. The hydraulic mechanism is provided with control means 27 connected to the servo valve 14, the electromagnetic direction switching valve 17, the electromagnetic opening / closing valves 23 and 26, and transmitting a signal for controlling the valve.
[0026]
Next, a method of operating the hydraulic mechanism of the mold clamping cylinder 6 and a method of bleeding air in this embodiment will be described. First, the servo valve 14 is excited to connect the P port and the A port, and the P port and the A port are connected while the electromagnetic direction switching valve 17 is not excited. As a result, the hydraulic oil is supplied from the supply source of the hydraulic oil to the booster cylinder 10, and the ram 8 and the movable platen 5 are moved at a relatively high speed to close the mold. At this time, the electromagnetic opening / closing valve 23 is also excited and switched to the open state. At the same time, the surge valve 20 is opened by the pilot pressure, and the tank 21 closes to the mold-clamping-side oil chamber 7 of the mold-clamping cylinder 6 in the negative pressure state. Hydraulic oil is supplied through a conduit 22 having a diameter. At this time, the electromagnetic opening / closing valve 26, which is an air release valve, is kept closed in a non-excited state. When the fixed mold 1a and the movable mold 5a come into contact with each other, the electromagnetic direction switching valve 17 is excited and switched, so that the P port and the B port communicate. At this time, the electromagnetic switching valve 23 is simultaneously switched to the non-excited state, and the surge valve 20 is closed. Then, the operating oil is supplied from a supply source of the operating oil to the mold clamping side oil chamber 7 in the mold clamping cylinder 6, and the pressure is increased.
[0027]
Then, injection molding of molten resin is performed from a not-shown injection device into a cavity formed between the fixed mold 1a and the movable mold 5a, and the molten resin is cooled and solidified in the cavity. After a lapse of a predetermined time for cooling and solidification, depressurization for reducing the pressure of the hydraulic oil in the mold-clamping-side oil chamber 7 in the mold-clamping cylinder 6 is performed. At the time of depressurization, while the surge valve 20 is closed, the electromagnetic opening / closing valve 26 as an air release valve is excited by a signal from the control means 27 to be switched from closed to open, and the mold is closed via the air release line 25. The side oil chamber 7 and the tank 21 communicate with each other. As a result, the working oil mixed with air into the tank 21 is returned from the mold-clamping-side oil chamber 7 in the positive pressure state. The hydraulic oil mixed with the air is separated from the difference in the specific gravity between the hydraulic oil and the air in the tank 21, and the air is discharged from the air breather disposed above the tank 21 as the oil level in the tank 21 rises. . In this embodiment, air bleeding is started only at the time of depressurization before opening the mold and at the time of low-speed mold opening during the molding cycle.
[0028]
Then, after the predetermined time elapses or shortly before or after the depressurization is completed, the electromagnetic on-off valve 23 is excited and switched from closed to open, and the surge valve 20 is opened. Further, the servo valve 14 is switched, and the P port and the B port are communicated to supply oil to the mold opening side oil chamber 9 of the mold clamping cylinder 6. At the same time, the electromagnetic direction switching valve 17 is switched to the non-excited state, and the P port and the A port are connected. As a result, the ram 8 and the movable platen 5 start moving in the mold opening direction. In this embodiment, the air bleeding by opening the electromagnetic opening / closing valve 26 is terminated when the movable platen 5 is opened at a low speed. However, the air bleeding may be terminated before the mold opening is started. When the mold opening is completed, the movable platen 5 is stopped at the mold opening completion position A. Then, the molded product is taken out at that position. In a normal molding cycle, the cycle from the start of mold closing to the removal of a molded product is repeatedly performed.
[0029]
In this embodiment, the molded product molded by the injection molding machine is a disk substrate such as a CD or DVD, and the hydraulic oil pressure of the hydraulic oil is controlled in multiple stages by a servo valve, so that the molten resin injected into the cavity is formed. While the mold is compressed. Therefore, in order to perform high-precision oil pressure control by the servo valve, air mixing in the mold clamping cylinder 6 particularly adversely affects the movement of the mold and the control of the clamping force, so it is necessary to completely remove the air.
[0030]
In the present invention, the air bleeding valve can be opened and air bleeding can be performed at an arbitrary timing other than the time of depressurization. In the present invention, the arbitrary timing refers not to sensing the pressure of the hydraulic oil but to a timing based on a signal from the control unit 27. Next, a description will be given of the air bleeding operation during the maintenance work of the mold other than the normal molding cycle. As shown in FIG. 1, the movable platen 5 shown in FIG. 1 is used for a mold maintenance operation performed with the mold attached, such as replacement of a stamper (not shown), removal of a sprue clogged in a sprue bush, and cleaning of impurities adhering to a cavity. Is retracted from the mold opening completion position A to the retreat limit position B to secure a wider working space between the movable mold 5a and the fixed mold 1a.
[0031]
When moving the movable platen 5 from the mold opening completion position A to the retreat limit position B, the electromagnetic valve 23 is de-energized and the surge valve 20 is closed. Then, the electromagnetic opening / closing valve 26 is excited to open, and the mold clamping side oil chamber 7 in the mold clamping cylinder 6 and the tank 21 are again communicated via the air vent pipe 25. The P port and the B port of the servo valve 14 are communicated with each other, and the electromagnetic direction switching valve 17 supplies the operating oil to the mold opening side oil chamber 9 of the mold clamping cylinder 6 in a non-excited state. Then, the ram 8 is further moved toward the mold opening side, the hydraulic oil in the mold clamping side oil chamber 7 becomes in a positive pressure state, and the tank 21 is moved from the air vent pipe 25 connected to the concave portion 24 on the upper part of the mold clamping cylinder 6. Will be collected. When the rear end 8c of the ram 8 contacts the rear side surface 6a of the mold clamping cylinder 6, the movement of the ram 8 to the retreat limit position B is stopped. The position where the ram 8 is stopped may be near the retreat limit position B.
[0032]
Note that the present invention is not limited to the above-described embodiment, and various modifications are possible. For example, the separation of the air from the hydraulic oil may be performed before the hydraulic oil is collected in the tank 21. Further, air bleeding at the time of depressurization may be performed every one molding cycle, or may be performed once every plural molding cycles. Further, the mold clamping cylinder is not limited to the one in which the volume of the mold clamping side oil chamber 7 is increased or decreased by the operation of the mold opening / closing means. Alternatively, other mold clamping cylinder types may be used.
[0033]
【The invention's effect】
The air releasing mechanism of the mold clamping cylinder of the present invention is connected to a mold clamping cylinder that performs mold clamping by supplying hydraulic oil to the mold clamping side oil chamber, and is connected to an upper part of the mold clamping side oil chamber and is opened and closed by a signal. Since the air release valve and control means for sending a signal to the air release valve at an arbitrary timing are provided, the air accumulated in the upper portion of the mold clamping side oil chamber in the mold clamping cylinder is determined by the difference in the specific gravity between the hydraulic oil and the air. Can be reliably vented. By using an air release valve that is opened and closed only when a signal is sent, air can be released at an arbitrary timing.
[0034]
Therefore, according to the present invention, it is possible to perform air bleeding even when the pressure of the hydraulic oil in the mold-clamping-side oil chamber in the mold-clamping cylinder after the mold-clamping is high can be performed, and the air bleeding can be performed without delaying the molding cycle. Can be. Further, the present invention does not have a problem that air is bleed even when pressure is increased as in an air bleeding mechanism using a cracking pressure, resulting in a loss of hydraulic oil pressure, and a problem that the cracking pressure needs to be adjusted. Has advantages.
[Brief description of the drawings]
FIG. 1 is a view showing a mold clamping cylinder and an air release mechanism of the present invention.
[Explanation of symbols]
1 ... fixed plate 1a ... fixed die 2 ... base 3 ... pressure receiving plate 4 ... tie bar 5 ... movable plate 5a ... movable die 6 ... mold clamping cylinder 7 ... ... mold closing side oil chamber 8 ... ram 8a ... one end 8b ... sliding part 8c ... rear end 9 ... mold opening side oil chamber 10 ... booster cylinder 11 ... oil chamber 12 ... hydraulic pump 13, 15, 16, 18, 19, 22 Pipe line 14 Servo valve 17 Electromagnetic direction switching valve 20 Surge valve 21 Tank 23, 26 Electromagnetic open / close valve 24 Recess 25 ... Air bleeding line 27 ... Control means

Claims (6)

A mold clamping cylinder that performs mold clamping by supplying hydraulic oil to the mold clamping side oil chamber;
An air release valve connected to the upper part of the mold-side oil chamber and opened and closed by a signal,
Control means for sending a signal to the air release valve at an arbitrary timing;
An air bleeding mechanism for a mold clamping cylinder. The hydraulic mechanism for supplying hydraulic oil to the mold clamping cylinder includes:
The air release mechanism of a mold clamping cylinder according to claim 1, wherein a servo valve is provided. The mold clamping cylinder,
A mold-side oil chamber in which the ram is moved together with the movable plate by the mold opening / closing means to increase or decrease the volume,
A surge valve connecting the mold-side oil chamber and the tank is provided;
The air vent valve is
The air release mechanism of a mold clamping cylinder according to claim 1 or 2, wherein the solenoid valve is an electromagnetic opening / closing valve connected to an upper portion of the surge valve connection position in the mold clamping side oil chamber. A recess is formed in the mold clamping cylinder at a position above and behind the stroke of the ram of the mold clamping side oil chamber,
The air bleeding mechanism according to any one of claims 1 to 3, wherein an air bleeding valve is connected to the recess. A mold clamping cylinder that performs mold clamping by supplying hydraulic oil to the mold clamping side oil chamber;
An air release valve connected to the upper part of the mold-side oil chamber and opened and closed by a signal,
An air bleeding mechanism of a mold clamping cylinder comprising a control unit for sending a signal to the air bleeding valve,
During the molding cycle, only during depressurization before opening the mold,
A signal is sent from the control means to switch the air release valve from closed to open,
A method of bleeding air from a mold clamping cylinder, which starts bleeding hydraulic fluid from a mold-side oil chamber in the mold clamping cylinder. A mold clamping cylinder having a mold clamping side oil chamber in which the ram is moved together with the movable plate by the mold opening / closing means to increase or decrease the volume and hydraulic fluid is supplied and the volume is increased at the time of mold clamping;
A surge valve connecting the mold-side oil chamber and the tank;
An air release valve connected to the upper part of the mold-side oil chamber and opened and closed by a signal,
Control means for sending a signal to the air release valve,
During mold maintenance work,
Close the surge valve at the mold opening completion position during the molding cycle and send a signal from the control means to open the air release valve,
The ram and movable platen are retracted again by the mold opening and closing means to the retreat limit position or the vicinity of the retreat limit position,
A method for bleeding air from a mold clamping cylinder, comprising bleeding hydraulic oil from a mold clamping side oil chamber in the mold clamping cylinder.

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