JP2002120046A - System for controlling hydraulic pressure in hydraulic cylinder in molding machine for mold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a system for controlling hydraulic pressure in a hydraulic cylinder of a molding machine for mold by squeezing molding sand in a molding chamber, squeezing members for squeezing the molding sand in the molding mutually approaching is actuated so as to make a necessary value of a mold hardness. SOLUTION: This system has the peculiarity, in which a pressure switch 25 is connected with the side supplying the hydraulic pressure for squeezing the molding sand at a supplying/ejecting oil hole in the hydraulic cylinder 28 and further, a timer for controlling the time for supplying the hydraulic pressure for squeezing the molding sand is arranged in a control panel for controlling the hydraulic cylinder.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic molding machine for squeezing molding sand in a molding chamber to form a mold. The present invention relates to a device for controlling the hydraulic pressure.

[0002]

2. Description of the Related Art Conventionally, as one of mold molding methods,
In some cases, molding sand is squeezed from molding sand in a molding chamber matched to a model plate to form a mold. In the squeeze, in a state where air or the like is trapped in the squeezed molding sand, the pressure switch operates at the set pressure value to forcibly complete the squeeze process. Therefore, the squeeze is completed in a state where the air in the mold is compressed, and as a result, a reverse compression force acts on the sand particles in the mold, and as a result, the sand particles are formed in the mold. There is a problem that the mold becomes uneven in hardness when the mold is raised. SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to provide an apparatus for controlling the hydraulic pressure of a hydraulic cylinder so as to make a mold hardness a required height.

[0003]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a molding machine for squeezing molding sand in a molding chamber to form a mold. A device for controlling a hydraulic pressure related to a hydraulic cylinder that operates a squeezing member for squeezing, wherein a pressure switch is connected to a side for supplying a hydraulic pressure for casting sand skies in a supply / drain hole of the hydraulic cylinder, and The present invention is characterized in that a timer for controlling a time for supplying hydraulic pressure for casting sand skies to a control panel for controlling the cylinder is provided.

[0004] In the above configuration, during the squeezing process, the pressure switch is turned on to confirm the set squeeze pressure while the hydraulic pressure rises to the set squeeze pressure, and the timer is operated for the set time. Hold the set squeeze pressure. By maintaining the set squeeze pressure in this way, the air in the mold is discharged, and the squeeze force is evenly applied to the sand grains of the mold, thereby securing the mold hardness.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a mold making apparatus to which the present invention is applied will be described below in detail with reference to the drawings.
A blow head 7 is mounted on a machine base (not shown), and a rotating frame 10 is mounted on the machine base so as to be vertically rotatable by 90 degrees. A hydraulic cylinder 28 extending along one end of the turning frame 10 is
Upper and lower squeezing members 4 and 8 are mounted on the other end of the piston rod extending along the other end and the moving frame 29, respectively. Further, between the upper and lower squeezing members, upper and lower frames which are fitted with the model plate and have blowing ports 5 and 6 respectively can enter and exit at an angle of 90 degrees.

The oil supply / drain hole A of the hydraulic cylinder 28
, A four-port three-position switching valve 20 is connected via a main pipe 21. In the hydraulic unit, a variable discharge pump 11 is connected to an oil tank (T) via a strainer (not shown), and the variable discharge pump 11 is connected to a check valve 19.
And a four-port three-position switching valve 20 is connected via a pressure supply pipe 14. A of 4 port 3 position switching valve 20
Ports include a pilot check valve 22 and a flow control valve 23
The main pipe 21 is connected to the flow control valve 23. In addition, B of the 4-port 3-position switching valve 20
The main pipe 27 is connected to the port via a flow control valve 26. The variable discharge pump 11 is provided with a relief valve 15 and a pressure control proportional solenoid valve 16 with a controller. A motor 13 is connected to the variable discharge pump 11 via a coupling 12. A gauge cock 17 and a pressure gauge 18 are connected to the pressure supply pipe 14 via a branch pipe. A throttle valve 24 and a pressure switch 25 are connected to the main pipe 21 via a branch pipe.

As shown in FIG. 1, after the model plate 3 is loaded between the upper and lower frames 1 and 2, the upper and lower frames 1, 2 and the model plate 3 are superposed. Are vertically rotated by 90 degrees by a rotating mechanism (not shown) to connect the sand blowing ports 5 and 6 of the upper and lower frames 1 and 2 to the sand blowing holes of the blow head 7. Next, the upper squeezing member 4 is slightly inserted into the other end opening of the upper frame 1 and the lower squeezing member 8 is slightly inserted into the other end opening of the lower frame 2, respectively.
A molding chamber 9 is defined by the model plate 3 and the upper and lower skies members 4 and 8. Next, from the blow head 7 to the molding chamber 9
Then, the molding cylinder 9 is blown, and the hydraulic cylinder 28 fixed to the moving frame 29 is extended to bring the upper and lower squeezing members closer to each other, thereby squeezing the molding sand in the molding chamber 9.

In this case, the maximum pressure of the hydraulic pressure supplied to the hydraulic cylinder for squeezing is, for example, a high pressure 16 MPa, a medium pressure 12 MPa, and a low pressure 8 MPa in a range of 21 MPa preset for the relief valve 15.
Is set in advance in the pressure control proportional solenoid valve 16 with a controller, and the operating pressure is set in the pressure switch 25 from -0.5 to -1 MPa from the low pressure. Also, a dedicated timer for keeping the squeeze pressure at a set value (for high pressure: T1, for medium pressure: T2, for low pressure: T
In 3), the time is set in the range of 0.3 to 2 seconds for each squeeze pressure.

Then, during the above-mentioned squeeze process, the set pressure of the pressure switch is turned on while the hydraulic pressure is rising to the set squeeze pressure, the set squeeze pressure is confirmed, and the dedicated timer is operated for the set time. Hold the set squeeze pressure. By maintaining the set squeeze pressure in this manner, the air in the mold is discharged, and the squeeze force is evenly applied to the sand grains of the mold to secure the mold hardness. After completing skis, 4 port 3 position switching valve 20
To supply the pressure oil to the B port side through the flow control valve 26 and the main pipe 27 to the AA port of the hydraulic cylinder to contract the hydraulic cylinder.

The mold making apparatus of the above embodiment is configured to blow the molding sand S from the sand blowing ports 5 and 6 of the upper and lower frames 1 and 2, but is not limited thereto. In essence, the point is that using a granular material such as molding sand having a certain degree of viscosity, the hardness of the sand of the molding sand in the molding chamber can be sufficiently increased by skies.
The present invention can be applied to any framed mold making apparatus.

[0011]

As is apparent from the above description, according to the present invention, during the squeeze process, the pressure switch is turned on while the hydraulic pressure is rising to the set squeeze pressure, and the set squeeze pressure is confirmed. Operates for the set time to maintain the set squeeze pressure. By maintaining the set squeeze pressure in this manner, there is an effect that the air in the mold is discharged and the squeeze force is evenly applied to the sand grains of the mold to secure the mold hardness.

[Brief description of the drawings]

FIG. 1 is a schematic diagram for explaining an embodiment of the present invention.

[Explanation of symbols]

 4 Upper skies member 8 Lower skies member 9 Molding room S molding sand 15 Relief valve 16 Pressure control proportional solenoid valve with controller 25 Pressure switch 28 Hydraulic cylinder

Claims (1)

[Claims] An apparatus for controlling a hydraulic pressure applied to a hydraulic cylinder for operating a squeezing member which approaches a squeezing member to squeeze molding sand in a molding chamber in a molding machine for squeezing molding sand in a molding chamber. A pressure switch is connected to a side of the oil supply / drain hole of the hydraulic cylinder that supplies hydraulic pressure for foundry sand skies, and further supplies hydraulic pressure for foundry sand skies to a control panel that controls the hydraulic cylinder. A hydraulic control device for a hydraulic cylinder in a molding machine, comprising a timer for controlling time.