JP4054231B2 - Control valve for injection machine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a control valve used for an injection machine such as a die casting machine, and more particularly to a control valve for an injection machine that enables high-speed response when increasing the shot pressure immediately before completion of a shot of molten metal.
[0002]
[Prior art]
Conventionally, in an injection machine such as a die-casting machine, when filling a molten metal into a mold cavity, the injection speed of the injection piston drops immediately before the completion of the shot of the molten metal. Therefore, it is common practice to increase the shot pressure.
[0003]
For example, Japanese Patent Application Laid-Open No. 61-193663 has an injection cylinder in which an injection piston and a pressure increasing piston are incorporated, and a hydraulic pressure source is provided on the pressure side of the injection piston via a check valve and an injection speed control valve. Further, there is disclosed a configuration in which a pressure increasing speed control valve is disposed between the hydraulic pressure source and the pressure increasing piston. In JP-A-61-193663, the speed of an injection piston is detected, and when the speed detection value falls below a predetermined value just before the molten metal is filled into the cavity, the pressure increase speed control valve is operated. A method is employed in which the shot pressure is increased by operating the pressure increasing piston.
[0004]
Japanese Patent Application Laid-Open No. 56-133103 discloses a pressure increase start valve and a pressure increase rise speed setting valve between a shot cylinder that pressurizes molten metal by hydraulic pressure and a pressure increase accumulator. The structure to perform is disclosed. In Japanese Patent Laid-Open No. 56-133103, the shot cylinder oil pressure at each shot is measured, and the measured pressure value is compared with the set oil pressure value so that the shot pressure is always within the setting allowable range. The control method is adopted.
[0005]
[Problems to be solved by the invention]
However, the injection speed control valve and the pressure-increasing speed control valve disclosed in Japanese Patent Laid-Open No. 61-193663 related to the above-mentioned prior art, and the Japanese Patent Laid-Open No. 56-131063 related to the above-mentioned prior art are disclosed. A spool valve is generally used as a valve structure in a control valve that controls a large amount of pressure oil, such as a pressure increase rise speed setting valve.
[0006]
In this case, in the control valve according to the prior art, the diameter of the spool becomes large in order to control a large amount of pressure oil, and the switching time for switching the open / close state of the spool is long, so that high speed response cannot be achieved. There is a problem that.
[0007]
The present invention has been made in consideration of the above-mentioned problems, and provides an injection machine control valve that can shorten the spool switching time when increasing the shot pressure and can achieve high-speed response. For the purpose.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the present invention is a control valve that is disposed between an injection cylinder and an accumulator and controls pressure oil supplied to the injection cylinder,
A sleeve formed with a primary port communicating with the accumulator and a secondary port communicating with the injection cylinder;
Provided to be slidably displaced in the sleeve, the valve open state in which the primary side port and the secondary port communicate with each other, and the communication between the primary side port and the secondary side port are blocked. A spool that switches between closed valve states,
A piston that engages with an end of the spool and is displaced integrally with the spool under the action of pressure oil supplied to the pressure chamber;
A valve body that blocks communication between the primary port and the secondary port by displacing along the hollow portion in the spool;
An elastic member for urging the valve body toward the primary port side;
It is characterized by providing.
[0009]
In this case, a guide hole for guiding the valve body when the valve body is slidably displaced may be formed on the inner wall surface of the spool. This is because when the valve body reaches the displacement end position of the guide hole, the communication state between the first communication hole and the second communication hole formed in the spool is reliably blocked.
[0010]
Further, by setting the inner diameter of the primary port formed in the sleeve to be smaller than the inner diameter of the end on the opposite side along the axial direction of the primary port, the accumulator side supplied from the primary port This is because even if the hydraulic pressure and the hydraulic pressure on the pressure chamber side are the same pressure, the spool can be operated smoothly due to the pressure receiving area difference due to the difference in the inner diameter.
[0011]
According to the present invention, when the shot to the cavity of the mold is completed and the injection cylinder is stalled, there is no flow of pressure oil from the primary side port to the secondary side port, and the valve body is attached by the elastic force of the elastic member. The valve body is displaced toward the primary port. Therefore, before the spool is switched from the valve open state to the valve closed state, the valve body slides and displaces along the inner wall surface of the spool, and the valve body closes the hollow portion of the spool so that A pressure relief state flowing toward the primary port is avoided.
[0012]
Therefore, in the present invention, since the hollow portion of the spool is closed by the valve body before the spool is switched from the valve open state to the valve closed state, the spool switching time when the shot pressure is increased is substantially reduced. It can be shortened to achieve high speed response.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Preferred embodiments of the control valve for an injection machine according to the present invention will be described below and described in detail with reference to the accompanying drawings.
[0014]
In FIG. 1, reference numeral 10 indicates an injection control mechanism of a die casting machine in which an injection control valve 12 according to an embodiment of the present invention is incorporated.
[0015]
The injection control mechanism 10 has an injection cylinder 18 in which an injection piston 14 and a pressure-increasing piston 16 are integrally incorporated. The injection piston 14 communicates with a mold cavity (not shown) via a piston rod 20. The injection head is connected to an injection head (not shown) provided in the injection sleeve.
[0016]
The injection control mechanism 10 includes an accumulator (ACC) 24 to which a gas cylinder 22 is attached. The accumulator 24 is connected to a primary port 28 of the injection control valve 12 through a first passage 26. ing. The secondary port 30 of the injection control valve 12 is connected via a second passage 32 so as to communicate with a pressurizing chamber 34 in which the injection piston 14 is accommodated.
[0017]
A pump 36 and a tank 38 are connected to the first passage 26, and a switching valve 40 is disposed between the accumulator 24 and the pressure increasing piston 16 via a branch passage.
[0018]
As shown in FIG. 2, the injection control valve 12 includes the sleeve 44 fitted in the recess of the block body 42 and a plurality of bolts 46 screwed into the screw holes of the block body 42. A first cover member 48 and a second cover member 50 that are fluid-tightly connected to one end of the sleeve 44 are included. A pressure chamber 54 to which pressure oil is supplied from a pressure oil supply source 52 (see FIG. 1) via a port (not shown) is provided inside the first and second cover members 48 and 50, and the pressure chamber 54 A first spring member 58 that biases the piston 56 together with the hydraulic pressure by the pressure oil is disposed inside.
[0019]
The sleeve 44 is formed with a primary port 28 that communicates with the first passage 26 and a secondary port 30 that communicates with the second passage 32, and is slidably displaced in the axial direction along the inner wall surface of the sleeve 44. As a result, a spool 60 for switching the communication state and the non-communication state of the primary side port 28 and the secondary side port 30 is provided. In this case, the inner diameter (φ1) of the primary port 28 of the sleeve 44 is smaller than the inner diameter (φ2) of the opposite end of the sleeve 44 (φ1 <φ2).
[0020]
At one end portion of the spool 60, a valve portion 64 which makes the primary side port 28 and the secondary side port 30 non-communicating by being seated on a seating portion 62 formed on the inner wall surface of the sleeve 44 (see FIG. 3). Reference), a first communication hole 66a and a second communication hole 66b for communicating the primary side port 28 and the secondary side port 30 respectively are provided.
[0021]
A piston 56 that is slidable along the inner wall surface of the sleeve 44 is disposed on the end portion side of the sleeve 44, and a flange portion 68 that engages with the end surface of the spool 60 is formed on the piston 56. The In this case, the piston 56 is urged toward the primary port 28 by the pressing force of the pressure oil supplied into the pressure chamber 54 and the first spring member 58, and the flange portion engages with the end surface of the spool 60. The valve portion 64 of the spool 60 is seated on the seat portion 62 via 68, and the valve is closed.
[0022]
A hollow portion 70 communicating with the first communication hole 66 a and the second communication hole 66 b is formed inside the spool 60, and the hollow portion 70 extends along a guide hole 72 formed on the inner wall surface of the spool 60. A displacing valve body 74 is provided. A second spring member (elastic member) 76 is disposed between the valve body 74 and the piston 56, and the valve body 74 is attached toward the primary port 28 side by the elastic force of the second spring member 76. It is energized.
[0023]
Accordingly, when the valve body 74 reaches the end position (displacement end position) 72a of the guide hole 72 by the elastic force of the second spring member 76, the valve body 74 closes the hollow portion 70 of the spool 60 and the spool The communication state between the first communication hole 66a and the second communication hole 66b formed in 60 is blocked (see FIG. 2). The valve body 74 is formed with a third communication hole 78 communicating with the second communication hole 66 b of the spool 60, and the end of the valve body 74 is closed by the piston 56.
[0024]
The injection control mechanism 10 in which the injection control valve 12 according to the embodiment of the present invention is incorporated is basically configured as described above. Next, the operation and effect thereof will be described.
[0025]
As shown in FIG. 2, under the action of the pressure oil supplied to the pressure chamber 54, the valve portion 64 of the spool 60 is seated on the seat portion 62 of the sleeve 44 and the primary port 28 is closed. And
[0026]
That is, the pressure oil supply source 52 is energized to supply pressure oil into the pressure chamber 54, and the piston 56 is connected to the primary port by the pressure oil supplied to the pressure chamber 54 and the pressing force of the first spring member 58. Press toward 28. At this time, since the flange portion 68 of the piston 56 and the end surface of the spool 60 are engaged, the spool 60, the valve body 74, and the piston 56 are integrally displaced toward the primary side port 28. As a result, the valve portion 64 of the spool 60 is seated on the seat portion 62 of the sleeve 44 and the primary port 28 is closed, whereby the supply of pressure oil from the accumulator 24 to the secondary port 30 is blocked.
[0027]
As described above, the inner diameter (φ1) of the primary port 28 of the sleeve 44 is smaller than the inner diameter (φ2) of the opposite end of the sleeve 44 (φ1 <φ2). ) Even if the hydraulic pressure supplied from the accumulator 24 and the hydraulic pressure supplied into the pressure chamber 54 are the same pressure, the spool 60 is set to be displaced toward the primary port 28 due to the pressure receiving area difference of the inner diameter. Has been.
[0028]
Next, as shown in FIG. 3, the spool 60 is displaced toward the piston 56 side to open the valve, and the primary side port 28 and the secondary side port 30 are communicated with each other so that the pressurized oil is injected into the injection cylinder 18. Is supplied to the pressurizing chamber 34.
[0029]
That is, the pressure oil supplied from the accumulator 24 is reduced by discharging the pressure oil supplied into the pressure chamber 54 through the discharge means (not shown) into the tank 38 and reducing the hydraulic pressure in the pressure chamber 54. Thus, the spool 60, the valve body 74, and the piston 56 are integrally displaced toward the right side in FIG.
[0030]
In this case, the pressure oil that has passed through the primary side port 28 is introduced into the hollow portion 70 through the first communication hole 66a of the spool 60, and overcomes the elastic force of the second spring member 76 to cause the valve body 74 to move toward the piston 56 side. Displace toward As a result, the pressure oil introduced into the hollow portion 70 of the spool 60 is supplied to the pressure chamber 34 of the injection cylinder 18 through the second communication hole 66b, the secondary port 30 and the second passage 32 of the spool 60, By displacing the injection piston 14, the molten metal is supplied into a cavity of a mold (not shown).
[0031]
When the shot is completed and the injection piston 14 of the injection cylinder 18 is stalled, there is no flow of pressure oil from the primary side port 28 to the secondary side port 30, in other words, the hydraulic pressure between the primary side port 28 and the secondary side port 30. Therefore, the valve body 74 is biased by the elastic force of the second spring member 76, and the valve body 74 is displaced toward the primary side port 28. In this case, the spool 60 is in a valve open state displaced toward the piston 56, and only the valve body 74 provided inside the spool 60 is displaced by the elastic force of the second spring member 76. When the valve body 74 is displaced and reaches the terminal position 72a of the guide hole 72 of the spool 60, the hollow portion 70 formed inside the spool 60 is closed by the valve body 74, and the primary side port 28 and The communication state with the secondary port 30 is blocked (see FIG. 4).
[0032]
As a result, the pressure oil supplied to the pressurizing chamber 34 of the injection cylinder 18 and pressurized to a desired hydraulic pressure flows into the primary port 28 side without switching the spool 60 from the valve open state to the valve closed state. Pressure escape can be prevented by the valve body 74.
[0033]
Subsequently, by energizing the pressure oil supply source 52 to supply pressure oil to the pressure chamber 54, the spool 60, the valve body 74, and the piston 56 are integrally displaced toward the primary side port 28. The primary port 28 is closed by the spool 60 to return to the valve closed state (see FIG. 2).
[0034]
In the injection control valve 12 according to the present embodiment, a valve body 74 that slides and displaces along a guide hole 72 formed on the inner wall surface of the spool 60 is provided. The state of pressure relief flowing into the port 28 is avoided.
[0035]
Therefore, in the injection control valve 12 according to the present embodiment, since the hollow portion 70 of the spool 60 is closed by the valve body 74 before the spool 60 is switched from the valve open state to the valve closed state, the shot pressure is reduced. High speed response can be achieved by substantially shortening the switching time of the spool 60 when increasing the pressure. As a result, the maintenance process after the high-speed shot can be switched in a short time.
[0036]
【The invention's effect】
According to the present invention, the following effects can be obtained.
[0037]
That is, a valve body that is urged by the elastic force of the elastic member is provided in the hollow portion of the spool, and the hollow portion of the spool is closed by the valve body before the spool switches from the valve open state to the valve closed state. Therefore, it is possible to achieve a high-speed response by substantially shortening the switching time of the spool when increasing the shot pressure. As a result, the maintenance process after the high-speed shot can be switched in a short time.
[Brief description of the drawings]
FIG. 1 is a block structure diagram of an injection control mechanism in which an injection control valve according to an embodiment of the present invention is incorporated.
FIG. 2 is a longitudinal sectional view showing a valve closed state of a spool constituting the injection control valve according to the embodiment of the present invention.
FIG. 3 is a longitudinal sectional view showing a valve open state in which the spool is displaced from the state of FIG. 2 and the primary side port and the secondary side port communicate with each other.
4 is a longitudinal sectional view showing a state in which the valve body is displaced from the state of FIG. 3 and the hollow portion of the spool is closed. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Injection control mechanism 12 ... Injection control valve 28 ... Primary side port 30 ... Secondary side port 44 ... Sleeve 54 ... Pressure chamber 56 ... Piston 58, 76 ... Spring member 60 ... Spool 66a, 66b, 78 ... Communication hole 70 ... Hollow part 72 ... Guide hole 72a ... Terminal position 74 ... Valve element

Claims (3)

A control valve disposed between an injection cylinder and an accumulator and controlling pressure oil supplied to the injection cylinder;
A sleeve formed with a primary port communicating with the accumulator and a secondary port communicating with the injection cylinder;
Provided to be slidably displaced in the sleeve, the valve open state in which the primary side port and the secondary port communicate with each other, and the communication between the primary side port and the secondary side port are blocked. A spool that switches between closed valve states,
A piston that engages with an end of the spool and is displaced integrally with the spool under the action of pressure oil supplied to the pressure chamber;
A valve body that blocks communication between the primary port and the secondary port by displacing along the hollow portion in the spool;
An elastic member for urging the valve body toward the primary port side;
A control valve for an injection machine comprising: The control valve for an injection machine according to claim 1,
A guide hole is formed on the inner wall surface of the spool to slide and displace the valve body. When the valve body reaches the displacement end position of the guide hole, the first communication hole and the second communication hole formed in the spool are formed. A control valve for an injection machine, wherein a communication state with a hole is cut off. In the control valve for an injection machine according to claim 1 or 2,
The control valve for an injection machine, wherein an inner diameter of a primary port formed in the sleeve is set smaller than an inner diameter of an end portion on the opposite side along the axial direction of the primary port.

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