JP2004076806A - Control valve for injection machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve high speed response by shortening a time for changing over a spool when intensifying shot pressure. <P>SOLUTION: This control valve for an injection machine comprises a sleeve 44 having a primary port 28 and a secondary port 30, the spool 60 for change-over between a valve opening condition and a valve closing condition, a piston 56 to be displaced integrally with the spool 60 under the operation of pressure oil supplied to a pressure chamber 54, and a valve element 74 for communication shut-off between a first communication hole 66a and a second communication hole 66b by the displacement along a hollow portion 70 in the spool 60 under the resilient operation of a second spring member 76. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a control valve used in an injection machine such as a die casting machine, and more particularly, to a control valve for an injection machine that enables a high-speed response when a shot pressure is increased immediately before a shot of a molten metal is completed.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, in an injection machine such as a die casting machine, when filling a cavity of a mold with a molten metal, an injection speed by an injection piston is lowered immediately before a shot of the molten metal is completed, so that an adverse effect on quality of a cast product is avoided. Therefore, it is common practice to increase the shot pressure.
[0003]
For example, Japanese Unexamined Patent Publication (Kokai) No. 61-193763 has an injection cylinder in which an injection piston and a pressure-intensifying piston are incorporated, and a hydraulic pressure source is provided on the pressurized side of the injection piston via a check valve and an injection speed control valve. There is disclosed a configuration in which a pressure increasing speed control valve is connected between the hydraulic pressure source and the pressure increasing piston. In the above-mentioned Japanese Patent Application Laid-Open No. 61-193763, the speed of the injection piston is detected, and when the detected speed drops to a predetermined value or less immediately before completion of filling the molten metal into the cavity, the pressure increasing 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. 56-131063 discloses that a pressure increasing start valve and a pressure increasing rising speed setting valve are provided between a shot cylinder which pressurizes and injects molten metal by operating with hydraulic pressure and a pressure increasing accumulator. Is disclosed. In JP-A-56-131063, a shot cylinder oil pressure at each shot is measured, and the measured oil pressure value is compared with a set oil pressure value, and an automatic computer is used so that the shot pressure is always within a set allowable range. A control method is employed.
[0005]
[Problems to be solved by the invention]
However, the injection speed control valve and the pressure increasing speed control valve disclosed in the above-mentioned prior art JP-A-61-193763, and the injection speed control valve disclosed in the above-mentioned prior art JP-A-56-131063 are disclosed. 2. Description of the Related Art In a control valve that controls a large amount of pressure oil, such as a pressure increasing rise speed setting valve, a spool valve is generally used as a valve structure.
[0006]
In this case, in the control valve according to the related art, the diameter of the spool becomes large in order to control the high-pressure hydraulic oil, and a high-speed response cannot be achieved because the switching time for switching the open / close state of the spool is long. There is a problem.
[0007]
SUMMARY OF THE INVENTION The present invention has been made in consideration of the above-described problems, and provides a control valve for an injection machine that can shorten a spool switching time when increasing a shot pressure and thereby achieve a high-speed response. The purpose is to:
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the present invention is a control valve disposed between an injection cylinder and an accumulator to control 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,
It is provided so as to be slidably displaced in the sleeve, and the valve open state in which the primary port and the secondary port communicate with each other, and the communication between the primary port and the secondary port is cut off. A spool for switching between a closed state and a closed state.
A piston engaged with an end of the spool and displaced integrally with the spool under the action of pressure oil supplied to a pressure chamber;
A valve body that is displaced along a hollow portion in the spool to shut off communication between the primary port and the secondary port;
An elastic member for urging the valve body toward the primary port side,
It is characterized by having.
[0009]
In this case, a guide hole for guiding the valve body when the valve body slides and displaces 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 between the first communication hole and the second communication hole formed in the spool is reliably shut off.
[0010]
Further, by setting the inner diameter of the primary port formed in the sleeve to be smaller than the inner diameter of the opposite end along the axial direction with respect to the primary port, the accumulator side supplied from the primary port is provided. This is because even if the oil pressure and the oil pressure on the pressure chamber side are the same, the spool can be smoothly operated by the pressure receiving area difference due to the difference in the inner diameter.
[0011]
According to the present invention, when the shot with respect to the cavity of the mold is completed and the injection cylinder is stalled, the flow rate of the pressure oil from the primary port to the secondary port disappears, and the valve element is attached by the elastic force of the elastic member. The valve body is urged to be 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 the secondary side port is closed. A pressure relief condition flowing into 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 switching time of the spool when increasing the shot pressure is substantially reduced. It is possible to achieve a high-speed response by shortening.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
BEST MODE FOR CARRYING OUT THE INVENTION A preferred embodiment of a control valve for an injection machine according to the present invention will be described below 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. Connected to an injection head (not shown) provided in the injection sleeve.
[0016]
The injection control mechanism 10 has an accumulator (ACC) 24 provided with a gas cylinder 22. The accumulator 24 is connected to a primary port 28 of the injection control valve 12 via a first passage 26. ing. The secondary port 30 of the injection control valve 12 is connected through a second passage 32 to a pressurizing chamber 34 in which the injection piston 14 is housed.
[0017]
A pump 36 and a tank 38 are connected to the first passage 26, and a switching valve 40 is arranged between the accumulator 24 and the pressure-intensifying piston 16 via a branch passage.
[0018]
As shown in FIG. 2, the injection control valve 12 includes a sleeve 44 fitted in a concave portion of the block body 42 and a plurality of bolts 46 screwed into screw holes of the block body 42. A first cover member and a second cover member are connected to one end of the sleeve in a liquid-tight manner. Inside the first and second cover members 48 and 50, there is provided 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). Inside, a first spring member 58 for urging the piston 56 together with the hydraulic pressure of the pressure oil is provided.
[0019]
A primary port 28 communicating with the first passage 26 and a secondary port 30 communicating with the second passage 32 are formed in the sleeve 44, and are slid in the axial direction along the inner wall surface of the sleeve 44. Accordingly, a spool 60 for switching between a communication state and a non-communication state of the primary port 28 and the secondary 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 of the spool 60, there is provided a valve portion 64 that makes the primary side port 28 and the secondary side port 30 in a non-communication state by sitting on a seating portion 62 formed on the inner wall surface of the sleeve 44 (FIG. 3). ), And a first communication hole 66a and a second communication hole 66b for communicating the primary port 28 and the secondary port 30, respectively.
[0021]
A piston 56 slidable along the inner wall surface of the sleeve 44 is provided on an end side of the sleeve 44, and the piston 56 is formed with a flange portion 68 that engages with an end surface of the spool 60. You. In this case, the piston 56 is urged toward the primary port 28 by the pressing force between the pressure oil supplied into the pressure chamber 54 and the first spring member 58, and the flange portion engages with the end face of the spool 60. The valve portion 64 of the spool 60 is seated on the seating portion 62 via the valve 68 to be in a valve closed state.
[0022]
A hollow portion 70 communicating with the first communication hole 66a and the second communication hole 66b 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 displaceable valve element 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 to the primary port 28 by the elastic force of the second spring member 76. It is being rushed.
[0023]
Therefore, when the valve element 74 reaches the end position (displacement end position) 72a of the guide hole 72 by the resilient force of the second spring member 76, the valve element 74 closes the hollow portion 70 of the spool 60 and The communication state between the first communication hole 66a and the second communication hole 66b formed in 60 is cut off (see FIG. 2). A third communication hole 78 communicating with the second communication hole 66b of the spool 60 is formed in the valve body 74, and an 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 operation and effect thereof will be described.
[0025]
As shown in FIG. 2, the valve portion 64 of the spool 60 is seated on the seat portion 62 of the sleeve 44 under the action of the pressure oil supplied to the pressure chamber 54, and the primary port 28 is closed. And
[0026]
That is, the pressure oil supply source 52 is energized to supply the pressure oil to the inside of the pressure chamber 54, and the pressure oil supplied to the pressure chamber 54 and the pressing force of the first spring member 58 cause the piston 56 to move to the primary side port. Press toward. At this time, since the flange portion 68 of the piston 56 is engaged with the end face of the spool 60, the spool 60, the valve element 74, and the piston 56 are displaced integrally toward the primary 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, so that the supply of the pressure oil from the accumulator 24 to the secondary port 30 is shut off.
[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, the spool 60 is set so as to be displaced toward the primary port 28 due to the pressure receiving area difference of the inner diameter. Have been.
[0028]
Next, as shown in FIG. 3, the spool 60 is displaced toward the piston 56 to open the valve, and the primary port 28 and the secondary port 30 are communicated with each other so that the hydraulic 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 to the pressure chamber 54 through the discharge means (not shown) into the tank 38 and reducing the oil pressure in the pressure chamber 54. As a result, the spool 60, the valve body 74, and the piston 56 are displaced integrally to the right in FIG.
[0030]
In this case, the pressure oil that has passed through the primary 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 move the valve element 74 to 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 pressurizing 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 the cavity of the mold (not shown).
[0031]
When the shot is completed and the injection piston 14 of the injection cylinder 18 is stalled, the flow rate of the pressure oil from the primary port 28 to the secondary port 30 disappears, in other words, the hydraulic pressure between the primary port 28 and the secondary port 30 Are substantially the same pressure, the valve element 74 is urged by the elastic force of the second spring member 76, and the valve element 74 is displaced toward the primary port 28. In this case, the spool 60 is in a valve-open state displaced toward the piston 56, and only the valve element 74 provided inside the spool 60 is displaced by the elastic force of the second spring member 76. When the valve element 74 is displaced and reaches the end 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 element 74, and the primary port 28 and The communication state with the secondary port 30 is cut off (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 oil pressure flows into the primary port 28 without switching the spool 60 from the valve open state to the valve closed state. Pressure relief can be prevented by the valve element 74.
[0033]
Subsequently, by urging the pressure oil supply source 52 to supply the 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 spool 60 returns to the valve closed state in which the primary port 28 is closed (see FIG. 2).
[0034]
In the injection control valve 12 according to the present embodiment, a valve element 74 that slides and displaces along a guide hole 72 formed on the inner wall surface of the spool 60 is provided. A pressure relief condition flowing into the port 28 is avoided.
[0035]
Therefore, in the injection control valve 12 according to the present embodiment, 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 switching time of the spool 60 when increasing the pressure is substantially shortened, and a high-speed response can be achieved. As a result, it is possible to switch to the maintenance process after the high-speed shot 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 element biased by the elastic force of the elastic member is provided in the hollow portion of the spool, and before the spool is switched from the valve open state to the valve closed state, the hollow portion of the spool is closed by the valve element. Therefore, it is possible to substantially shorten the switching time of the spool when increasing the shot pressure and achieve a high-speed response. As a result, it is possible to switch to the maintenance process after the high-speed shot in a short time.
[Brief description of the drawings]
FIG. 1 is a block diagram of an injection control mechanism incorporating an injection control valve according to an embodiment of the present invention.
FIG. 2 is a longitudinal sectional view showing a 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 a spool is displaced from a state of FIG. 2 and a primary port and a secondary port communicate with each other.
FIG. 4 is a longitudinal sectional view showing a state where the valve body is displaced from the state of FIG. 3 and the hollow portion of the spool is closed.
[Explanation of symbols]
10 Injection control mechanism 12 Injection control valve 28 Primary port 30 Secondary 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

Claims (3)

A control valve disposed between an injection cylinder and an accumulator, for 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,
It is provided so as to be slidably displaced in the sleeve, and the valve open state in which the primary port and the secondary port communicate with each other, and the communication between the primary port and the secondary port is cut off. A spool for switching between a closed state and a closed state.
A piston engaged with an end of the spool and displaced integrally with the spool under the action of pressure oil supplied to a pressure chamber;
A valve body that is displaced along a hollow portion in the spool to shut off communication between the primary port and the secondary port;
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 through which the valve body slides is formed on the inner wall surface of the spool. When the valve body reaches the displacement end position of the guide hole, a first communication hole formed in the spool and a second communication hole are formed. A control valve for an injection machine, wherein a state of communication with a hole is shut off. The control valve for an injection machine according to claim 1 or 2,
A 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 opposite to the primary port in the axial direction.

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