JP3849665B2 - Impact testing machine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an impact tester that applies impact to a test piece to obtain impact fracture characteristics and the like.
[0002]
[Prior art]
In the impact tester, the lower oil chamber of the hydraulic cylinder communicates with the tank, and the pressure accumulated in the accumulator is guided to the upper oil chamber, so that the piston rod is extended (lowered) at high speed and attached to the tip of the piston rod. The test jig thus made is collided with the test piece and destroyed. The impact fracture characteristics of the specimen can be obtained from the data at the time of the collision. The descending speed of the piston rod can be changed by controlling the return oil from the lower oil chamber with a flow rate control valve such as a servo valve (see, for example, Patent Document 1).
[0003]
After the test is completed, pump pressure is guided to the upper and lower oil chambers of the hydraulic cylinder, and the piston rod is contracted (increased) by the differential pressure generated by the difference in the pressure receiving area of the piston (upper <lower). As a result, the test jig can be gently returned to the initial position.
[0004]
[Patent Document 1]
Japanese Patent Publication No. 7-54290 [0005]
[Problems to be solved by the invention]
Conventionally, the impact test is based on the premise that the specimen is destroyed. However, with the recent progress of materials, some materials may not be destroyed even if an impact is applied. In this case, the colliding test jig is restrained by the test piece, and the test jig may not be restored only by the difference in the pressure receiving area.
[0006]
An object of the present invention is to provide an impact tester capable of returning a test jig without any problem even when a test piece is not broken.
[0007]
[Means for Solving the Problems]
The impact testing machine according to the present invention has a piston rod on which an impact test jig is mounted, and extends the piston rod by the pressure to the first oil chamber, and the piston rod by the pressure to the second oil chamber. A hydraulic cylinder that contracts, an accumulator that accumulates the discharge pressure of the hydraulic pump, a pump communication position that communicates at least the second oil chamber with the hydraulic pump, and a tank communication position that communicates with the tank. A flow rate control valve that controls the flow rate of the return oil at the communication position, a pump communication position that is interposed between the hydraulic pump and the accumulator and communicates the first oil chamber with the hydraulic pump, and a tank communication position that communicates with the tank The switching rod can be switched to the tank communication position, the switching valve is in the pump communication position, and the piston rod is extended by the accumulated pressure of the accumulator. The test jig is made to collide with the test piece, the flow rate control valve is set to the pump communication position, and the switching valve is set to the tank communication position so that the piston rod contracts and the test jig is returned. .
In particular, according to the second aspect of the present invention, the first relief valve that limits the discharge line pressure of the hydraulic pump to the first pressure and the discharge line pressure of the hydraulic pump to the second pressure that is lower than the first pressure. A second relief valve to limit and a selection valve to select one of the first and second relief valves, and at least when the pressure for the impact test is stored in the accumulator, the first relief valve is selected; When the first relief valve is not selected, the second relief valve is selected.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is an overall configuration diagram of an impact tester in the present embodiment. A cross yoke 3 is supported on the support 1 via a support column 2, and a hydraulic cylinder 4 is supported on the cross yoke 3. A punch 5 as an impact test jig is attached to the tip of the lower piston rod 4c that can expand and contract with respect to the cylinder tube 4a. A plate-shaped test piece TP is placed on the support table 1 at a position facing the punch 5 via a receiving table 6, and a pressing plate 7 (FIG. 2) is arranged on the upper side of the test piece TP. When the lower piston rod 4c is extended (lowered) at high speed, the punch 5 passes through the opening of the holding plate 7 and collides with the test piece TP. A load cell 5a is incorporated in the punch 5, and the load at the time of collision of the test piece is sent to the controller 21 in FIG.
[0009]
FIG. 3 shows a hydraulic system and a control system of the impact tester. The hydraulic cylinder 4 has a reciprocating piston 4b that moves up and down in the cylinder tube 4a, and the above-described lower piston rod 4c and upper piston rod 4d are connected to the piston 4b. The upper piston rod 4d is inserted into, for example, a capacitance type displacement detector 22 that detects the amount of displacement of the piston 4b, and the detection signal of the displacement detector 22 is input to the controller 21 as a displacement signal.
[0010]
An electromagnetic switching valve (hereinafter referred to as an electromagnetic valve) 12 and an accumulator 13 are provided in a pipe line connecting the hydraulic pump 11 and the upper oil chamber 4U of the hydraulic cylinder 4. When the solenoid valve 12 holds the position B (pump communication position) as shown in the figure, the discharge pressure of the hydraulic pump 11 is guided to the upper oil chamber 4U and the accumulator 13 is pressurized. On the other hand, when the solenoid valve 12 is switched to the low position (tank communication position) by a signal from the controller 21, the upper oil chamber 4U is communicated with the tank.
[0011]
The servo valve 15 as a flow rate control valve is controlled by a signal from the controller 21, a state where the lower oil chamber 4 </ b> L of the hydraulic cylinder 4 communicates with the hydraulic pump 11, a state where it communicates with the tank 14, the hydraulic pump 11, Switching to a state in which any of the tanks 14 is blocked is possible. When the lower oil chamber 4L communicates with the tank 14, the flow rate of the return oil to the tank 14 is controlled by the servo valve 15, so that the moving speed of the lower piston rod 4c, that is, the impact destruction to the test piece TP is prevented. It is possible to arbitrarily switch the speed for a predetermined range.
[0012]
Both 16 and 17 are relief valves for limiting the discharge pressure of the hydraulic pump 11, and the relief valve 17 is set to have a lower set pressure than the relief valve 16. The use of the relief valves 16 and 17 will be described later, but which one of the relief valves is used is selected by the electromagnetic valve 18. The solenoid valve 18 is also switched by the controller 21.
[0013]
An operation panel 30 is also connected to the controller 21. As shown in FIG. 4, the operation panel 30 includes a power switch 31, a start switch 32 for instructing a test start, a charge switch 33 for instructing the accumulator 13, and an up / down position for adjusting the vertical position of the punch 5. / Down switches 34 and 35, a RUN switch 36 for operating the hydraulic pump 11 at a low pressure, a return switch 37 for returning the piston rod 4c to the initial state, and the like.
[0014]
The procedure of the impact test by the impact tester configured as described above will be described.
First, the power switch 31 is operated. In the initial state, the electromagnetic valve 12 is in the A position, and the accumulator 13 and the upper oil chamber 4U of the hydraulic cylinder 4 are communicated with the hydraulic pump 11. The solenoid valve 18 is at a position b where the low pressure relief valve 17 is selected. The servo valve 15 shuts off the lower oil chamber 4L of the hydraulic cylinder 4 and the tank 14, and also shuts off the lower oil chamber 4L from the hydraulic pump 11, and the hydraulic pump 11 is stopped.
[0015]
When the RUN switch 36 is operated in this state, the controller 21 drives the hydraulic pump 11 while holding the solenoid valve 12 in the A position. As a result, the hydraulic pressure acts on the accumulator 13, but since the low pressure relief valve 17 is selected, the discharge line of the hydraulic pump 11 is held at a low pressure, and the accumulator 13 is not pressurized. At this time, since the servo valve 15 blocks the lower oil chamber 4L and the tank 14, the hydraulic cylinder 4 is not driven. This state is a low-pressure operation state.
[0016]
The vertical position of the punch 5 is adjusted by the vertical switches 34 and 35 in the low pressure operation state. When the lower switch 35 is operated, the servo valve 15 causes the lower oil chamber 4L to communicate with the tank 14, whereby the piston 4b, that is, the punch 5 is lowered at a low pressure. When the operation of the lower switch 35 is released, the lower oil chamber 4L is shut off from the tank 14, and the piston 4b stops. When the upper switch 34 is operated, the servo valve 15 communicates the lower oil chamber 4L with the hydraulic pump 11. As a result, the pump pressure acts on both the upper oil chamber 4U and the lower oil chamber 4L. However, since the lower pressure receiving area of the piston 4b is larger than the upper pressure receiving area, the piston 4b, that is, the punch 5 rises at a low pressure. When the operation of the upper switch 34 is released, the lower oil chamber 4L is shut off from both the hydraulic pump 11 and the tank 14 by the servo valve 5, whereby the piston 4b stops. In the low pressure operation state, the piston 4b does not move at high speed, and the adjustment work can be performed accurately and safely.
[0017]
When the charge switch 33 is operated, the electromagnetic valve 18 is switched to the position a for selecting the high pressure relief valve 16, and the discharge line pressure of the hydraulic pump 11 is increased to enter the high pressure operation state. Although the solenoid valve 12 is in the A position, the servo valve 15 shuts off the lower oil chamber 4L from both the hydraulic pump 11 and the tank 14, so the hydraulic cylinder 4 is not driven and high hydraulic pressure is accumulated in the accumulator 13. Is done.
[0018]
When the start switch 32 is operated after the stock pressure, the servo valve 15 communicates the lower oil chamber 4L with the tank 14. Since the solenoid valve 12 holds the A position, the piston 4b descends at a high speed due to the high pressure accumulated in the accumulator 13, and the punch 5 attached to the piston rod 4c collides with the test piece TP. The controller 21 reads the output of the load cell 5a and the output of the displacement detector 22 at that time, and processes these data to obtain the impact fracture characteristics and the like of the test piece TP. When the piston 4b moves to the stop position and the test is completed, the controller 21 switches the electromagnetic valve 18 to the b position and automatically enters the low pressure operation state.
[0019]
Thereafter, when the return switch 37 is operated to return the punch 5 to the initial position, the solenoid valve 12 is switched to the low position, the upper oil chamber 4U communicates with the tank 14, and the servo valve 15 hydraulically controls the lower oil chamber 4L. Communicate with the pump 11. Accordingly, the piston 4b is raised by the pump pressure, and the return operation of the punch 5 can be performed. When the punch 5 rises to the initial position, the lower oil chamber 4L is shut off from both the hydraulic pump 11 and the tank 14 by the servo valve 5, whereby the piston 4b stops.
[0020]
In this way, the pump pressure is guided to the lower oil chamber 4L, and the upper oil chamber 4U is communicated with the tank 14 to perform the return operation. Therefore, the force is larger than the return operation based only on the pressure receiving area difference of the piston 4b. Can be demonstrated. Therefore, even when the impact is applied, the test piece TP is not broken, and even if the punch 5 is restrained by the test piece TP, the punch 5 can be reliably returned to the initial position. Moreover, in the present embodiment, the low pressure relief valve 17 is selected at the time of punch position adjustment and return operation, so that a gradual operation can be realized and safety is improved.
[0021]
If safety can be ensured without switching to the low pressure relief valve during the return operation of the punch 5, the low pressure relief valve and the relief valve selection function can be omitted.
[0022]
【The invention's effect】
According to the present invention, the return operation of the test jig is performed by setting the flow control valve to the pump communication position and the switching valve to the tank communication position, so that the test jig is restrained without breaking the test piece. Even in this case, it is possible to reliably return the test jig.
[Brief description of the drawings]
FIG. 1 is an overall configuration diagram of an impact tester according to an embodiment of the present invention.
FIG. 2 is an enlarged view showing a punch and a test piece mounting portion.
FIG. 3 is a diagram showing a hydraulic system and a control system of an impact tester.
FIG. 4 is a diagram showing an operation panel of an impact tester.
[Explanation of symbols]
4 Hydraulic cylinder 4b Piston 4c Lower piston rod 4U Upper oil chamber 4L Lower oil chamber 5 Punch 11 Hydraulic pump 12, 18 Solenoid valve 13 Accumulator 14 Tank 15 Servo valve 16 Relief valve (high pressure)
17 Relief valve (low pressure)
21 Controller 30 Operation panel TP Test piece

Claims (2)

A hydraulic cylinder having a piston rod to which an impact test jig is mounted, extending the piston rod by the pressure to the first oil chamber, and contracting the piston rod by the pressure to the second oil chamber; and a hydraulic pump An accumulator that accumulates the discharge pressure of the oil, a pump communication position that communicates at least the second oil chamber with the hydraulic pump, and a tank communication position that communicates with the tank, and the flow rate of return oil at the tank communication position A flow control valve for controlling the pressure, and a pump communication position that is interposed between the hydraulic pump and the accumulator and communicates the first oil chamber with the hydraulic pump, and a tank communication position that communicates with the tank. And the switching valve is in the tank communication position, the switching valve is in the pump communication position, and the piston is controlled by the accumulated pressure of the accumulator. The test rod is extended so that the test jig collides with the test piece, and the flow control valve is set to the pump communication position and the switching valve is set to the tank communication position, so that the piston rod contracts and the test treatment is performed. An impact tester characterized by returning the tool. A first relief valve that limits the discharge line pressure of the hydraulic pump to a first pressure; and a second relief valve that limits the discharge line pressure of the hydraulic pump to a second pressure lower than the first pressure. A relief valve and a selection valve for selecting one of the first and second relief valves, and at least when the accumulator stores a pressure for an impact test, the first relief valve is selected, and the first relief valve is selected. 2. The impact tester according to claim 1, wherein when the first relief valve is not selected, the second relief valve is selected.

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