JP3347927B2 - Material testing machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a material testing machine, and more particularly to an electro-hydraulic material testing machine which controls a single-acting hydraulic cylinder for applying a load to a test piece by an electro-hydraulic servo valve.

[0002]

2. Description of the Related Art FIG. 2 shows a material testing machine disclosed in Japanese Utility Model Publication No. 7-4548, in which a single-acting hydraulic cylinder 1 has a ram 2, and the ram 2 has a testing machine main body. Table 3 is attached. The three-way valve controlled electro-hydraulic servo valve 4 has ports A, B and C. The port C is connected to the cylinder chamber 1a of the single acting hydraulic cylinder 1 by a pipe 5a, and the port A is connected to a pipe 5b and a filter 6a. Is connected to the hydraulic pump 7 through the port B, and the port B
Is connected to the tank 9. The intermediate portion of the single acting hydraulic cylinder 1 is connected to the tank 9 via a pipe 5d and a relief valve 10, and the pipe 5a is connected to the tank 9 via a pipe 5e and a safety valve 11. The solenoid valve 12 dedicated to ram return is connected between the cylinder chamber 1a of the single-acting hydraulic cylinder 1 and the tank 9 by a pipe 5a and a pipe 5f.

[0003] The automatic load control unit 13 controls the electrohydraulic servo valve 4, and the power measuring machine 14 detects the output of the single acting hydraulic cylinder 1. At the time of material test, that is, at the time of load, the three-way valve controlled electro-hydraulic servo valve 4 communicates the port A with the port C, whereby hydraulic oil is sent from the hydraulic pump 7 to the cylinder chamber 1a of the single acting hydraulic cylinder 1. , The ram 2 is raised and a load is applied to the test piece on the table 3. The magnitude of the load at this time is detected by the power meter 14.

At the end of the material test, that is, at the time of unloading, the electro-hydraulic servo valve 4 communicates the port B with the port C, so that the pressure oil in the cylinder chamber 1a of the single-acting hydraulic cylinder 1 is discharged by the electro-hydraulic servo valve. It is gradually discharged to the tank 9 via the valves 4 and 8. At the same time, the solenoid valve 1 dedicated to ram return
2 is opened, the pressure oil in the cylinder chamber 1a is rapidly discharged to the tank 9 via the solenoid valve 12, and the ram 2 is quickly returned to the initial position.

[0005]

However, in the above-described conventional material testing machine, the operation is complicated because it is necessary to independently control the electrohydraulic servo valve and the solenoid valve dedicated to ram return at the time of unloading. There is a problem that is.

An object of the present invention is to provide a material testing machine which is very simple to operate and can open a ram return valve by controlling an electrohydraulic servo valve.

[0007]

In order to achieve this object, the present invention provides a single-acting hydraulic cylinder for applying a load to a test piece, a hydraulic pressure generating source, a tank, the single-acting hydraulic cylinder, A ram return relief valve connected between the tank and the single-acting hydraulic cylinder for rapidly discharging the hydraulic fluid in the single-acting hydraulic cylinder to the tank when the valve is opened; and a first port connected to the hydraulic pressure source And a second port connected to the tank, a third port connected to the single-acting hydraulic cylinder, and a fourth port connected to the ram return relief valve. An electro-hydraulic servo valve, wherein the electro-hydraulic servo valve communicates the first port and the third port when in the load position, and communicates with the second port and the fourth port. And communicate between the first port and the third port. The hydraulic fluid is supplied to the single-acting hydraulic cylinder from the hydraulic pressure source through the first port, the first port and the fourth port communicate with each other at the time of the unloading position, and the second port and the second port communicate with each other. 3 port and the first port
And the fourth port communicates with the fourth port to supply pressure fluid from the hydraulic pressure source to the relief valve for returning the ram to open the relief valve for returning the ram. is there.

[0008] The electrohydraulic servo valve communicates the first port with the third port and communicates the second port with the fourth port when in the load position. By the communication between the first port and the third port, a hydraulic fluid is supplied from a hydraulic pressure source to a single-acting hydraulic cylinder via an electrohydraulic servo valve, whereby a load is applied to the test piece. In addition, the communication between the second port and the fourth port keeps the ram return relief valve closed.

The electro-hydraulic servo valve communicates the first port with the fourth port and communicates the second port with the third port when in the unloading position. With the communication between the second port and the third port, the hydraulic fluid is gradually discharged from the single acting hydraulic cylinder to the tank via the electrohydraulic servo valve.
In addition, by the communication between the first port and the fourth port,
The hydraulic fluid is supplied from the hydraulic pressure source to the relief valve for ram return via the electrohydraulic servo valve, and the relief valve for ram return is opened. By opening the relief valve for returning the ram, the hydraulic fluid is quickly discharged from the single-acting hydraulic cylinder to the tank via the relief valve for returning the ram. By discharging the hydraulic fluid through the relief valve for returning the ram, the ram of the single-acting hydraulic cylinder quickly returns. As described above, since the relief valve for ram return is opened by the four-way valve-controlled electro-hydraulic servo valve, the relief valve for ram return is reliably opened, and the operation is very simple. Become.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of a material testing machine according to the present invention, in which the same parts as those in FIG.
This will be described with reference to FIG. In FIG. 1, a single-acting hydraulic cylinder 1 has a ram 2 to which a table 3 of a tester main body is attached. The four-way valve controlled electro-hydraulic servo valve 15 has ports A, B, C and D
And is controlled by the automatic load control unit 13. The port A of the electrohydraulic servo valve 15 is connected to the hydraulic pump 7 through the pipe 5b and the filter 6, and the port B
Is connected to a tank 9 via a pipe 5c and a valve 8, port C is connected to a cylinder chamber 1a of the single acting hydraulic cylinder 1 via a pipe 5a, and port D is a relief for returning the ram via a pipe 5g. Connected to valve 16.

The intermediate portion of the single-acting hydraulic cylinder 1 is connected to a tank 9 via a pipe 5d and a relief valve 10, and the cylinder chamber 1a of the single-acting hydraulic cylinder 1 is connected to a tank 9 via a pipe 5e and a safety valve 11. It is connected to the. The ram return relief valve 16 is connected between the cylinder chamber 1a of the single-acting hydraulic cylinder 1 and the tank 9 by a pipe 5a and a pipe 5f. The automatic load control unit 13 controls the electrohydraulic servo valve 15 of the four-way valve control, and the power meter 14 detects the output of the single-acting hydraulic cylinder 1.

Next, the operation of this embodiment will be described. At the time of material test, that is, at the time of load, the automatic load control unit 13 controls the electrohydraulic servo valve 15 of the four-way valve control to connect the ports A and C, and to connect the ports B and D.
And communicate with. Due to the communication between the port A and the port C, pressure oil is sent from the hydraulic pump 7 to the cylinder chamber 1a of the single acting hydraulic cylinder 1 via the electrohydraulic servo valve 15, whereby the ram 2 rises and the table 3 A load is applied to the upper specimen. The magnitude of the load at this time is detected by the power meter 14. The communication between the port B and the port D closes the ram return relief valve 16.
When the electrohydraulic servo valve 15 is subsequently switched to the neutral position, the load state at that time is maintained.

At the end of the material test, that is, at the time of unloading, the automatic load control unit 13 controls the electrohydraulic servo valve 15 of the four-way valve control to connect the ports A and D, and to connect the ports B and C to each other. To communicate. By the communication between the port B and the port C, the pressure oil in the cylinder chamber 1a of the single acting hydraulic cylinder 1 is gradually discharged to the tank 9 via the electrohydraulic servo valve 15 and the valve 8. At the same time, the communication between the port A and the port D causes the hydraulic fluid from the hydraulic pump 7 to supply the hydraulic fluid to the pipe 5b, the electrohydraulic servo valve 15, and the
Is supplied to the relief valve 16 for returning the ram, and the relief valve 16 for returning the ram is opened. When the relief valve 16 for returning the ram is opened, the hydraulic fluid is discharged from the cylinder chamber 1a of the single-acting hydraulic cylinder 1 to the relief valve 16 for returning the ram.
Through the tank 9. Thus, the ram 2 of the single acting hydraulic cylinder 1 quickly returns to the initial position.

As described above, the four-way valve-controlled electrohydraulic servo valve 15 communicates the cylinder chamber 1a of the single-acting hydraulic cylinder 1 with the tank 9 in response to a command from the automatic load control unit 13 at the time of unloading. The relief valve 16 for ram return is driven to open. Therefore, the opening of the electrohydraulic servo valve and the relief valve for ram return are controlled by the electrohydraulic servo valve, and the operation becomes very simple.

[0015]

As is apparent from the above description, according to the present invention, the operation of the relief valve for returning the ram is very simple because it is opened by the electrohydraulic servo valve controlled by the four-way valve. At the same time, reliability is improved.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an embodiment of a material testing machine according to the present invention.

FIG. 2 is a schematic view showing a conventional material testing machine.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Single-acting hydraulic cylinder 2 Ram 7 Hydraulic pressure generation source (hydraulic pump) 9 Tank 15 Electrohydraulic servo valve of four-way valve control 16 Relief valve for ram return A First port of electrohydraulic servo valve B Electrohydraulic Second port of electrohydraulic servovalve C Third port of electrohydraulic servovalve D Fourth port of electrohydraulic servovalve

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G01N 3/10 JICST file (JOIS)

Claims (1)

(57) [Claims] 1. A single-acting hydraulic cylinder for applying a load to a test piece, a hydraulic pressure source, a tank, and connected between the single-acting hydraulic cylinder and the tank. A ram return relief valve for rapidly discharging the pressurized liquid in the pressure cylinder to the tank; a first port connected to the hydraulic pressure generation source; a second port connected to the tank; A four-way valve controlled electro-hydraulic servo valve having a third port connected to a hydraulic cylinder and a fourth port connected to the relief valve for returning the ram, wherein the electro-hydraulic servo The valve communicates the first port with the third port and communicates the second port with the fourth port when in the load position, and communicates the first port with the third port. Hydraulic fluid from the hydraulic pressure source through the single-acting hydraulic system Supplied to Sunda, communicates the communicating and the second port and the third port and the first port and the fourth port when the unloading position, the first
A material test, comprising supplying hydraulic fluid from the hydraulic pressure source to the relief valve for returning to the ram and opening the relief valve for returning to the ram by communication between the first port and the fourth port. Machine.