JPH0345781B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Field of Industrial Application The present invention relates to an apparatus for stopping a material testing machine in a state where no undesirable load is applied to the test piece when the drive of the material testing machine is stopped.

(B) Prior Art When a material testing machine reaches a certain test condition and the test is stopped, this has conventionally been done by, for example, stopping the hydraulic power source of the actuator of the testing machine. However, according to this method, the weight of the piston of the actuator, the grip, etc. acts on the test piece, making it impossible to recover the test piece in the final state of the test. Conventionally, in order to prevent this phenomenon, a sub-control loop was added to the control loop during the test without stopping the hydraulic power source, for example, by controlling the stroke of the actuator and stopping the piston at the desired position. Methods such as having the However, even with this, the main control signal from the test remained, so it was not possible to completely eliminate the load acting on the test piece.

(c) Purpose An object of the present invention is to be able to stop the testing machine without applying any load to the test piece when a test stop command is issued. An object of the present invention is to provide a test piece protection stop device for a material testing machine.

(d) Configuration The present invention is characterized by a circuit means for forcibly setting the control amount of the servo mechanism that controls the actuator of the load mechanism as a load when a test stop command is issued, and setting the target value to zero; A circuit means for inserting a sub-control loop into the servo mechanism that feeds back the detected displacement value of the actuator to the displacement target value when the test stop command is issued, and when the test stop command is issued, the actuator is controlled by the load that makes the target load value zero. The present invention is configured to be driven by a control loop of both control and displacement control for controlling the actuator to a predetermined target stop position.

(e) Examples Examples of the present invention will be described below based on the drawings.

The drawing is a block diagram showing the configuration of an embodiment of the present invention.

The actuator 1 that applies a load to the test piece W is
The drive is controlled by a hydraulic servo mechanism including a servo amplifier 2 and a servo valve 3. The load acting on the test piece W due to the drive of the actuator 1 is detected by the load cell 4 and the load amplifier 5, and the displacement of the piston of the actuator 1 is detected by the displacement detector 6 and the stroke amplifier 7, respectively.

The input signal supplied to the servo amplifier 2 is configured so that different input signals are supplied at the time of testing and at the time of stopping the test by a changeover switch S1. The changeover switch S1 assumes the state shown in the figure during testing, and is automatically switched when a test stop command is issued.

A target value signal during the test is generated by the test waveform generator 8, and a deviation signal obtained by feeding back the above-mentioned load detection value or displacement detection value to the target value signal is sent to the servo amplifier via the changeover switch S1. 2 is input. Note that any feedback signal during the test can be selected by operating the selection switch S2.

The target value signal at the time of stopping the test is generated by the load zero signal generator 9. The zero load signal generator 9 generates a target value signal such that the load acting on the test piece W becomes zero. When a test stop command is issued, a deviation signal obtained by feeding back the load detection value from the load amplifier 5 to the target value signal from the load zero signal generator 9 is input to the servo amplifier 2 via the changeover switch S1. In addition, this input signal is supplied to a displacement target value signal generator 10 provided separately.
A deviation signal obtained by feeding back the detected displacement value from the stroke amplifier 7 is superimposed on the output signal from the stroke amplifier 7, and a sub-control loop that uses this displacement as the controlled variable is added to the main control loop that uses the above-mentioned load as the controlled variable. It will be done.

According to the above-described embodiment of the present invention, during a test, the actuator 1 is driven and controlled by an arbitrary control amount according to the target value signal from the test waveform generator 8, but when a test stop command is issued, , the changeover switch S1 is automatically switched, and the control is switched to a main control in which the load is the controlled variable and its target value signal is zero, and a sub-control is added that uses the displacement of the actuator 1 as the controlled variable. . Therefore, when the test is stopped, the actuator 1 is driven and stopped so that the load is always zero, regardless of the control amount and its magnitude during the test.

In the above embodiment, the load target value is immediately set to zero when the test stop command is issued, but the load value at the time of the test is memorized, and the load value is gradually reduced to zero from that value, for example, according to a preset slope. It is also possible to generate such a load target value signal.

(f) Effects As explained above, according to the present invention, when a test stop command is issued, the main control is automatically performed using the load to make the target value zero, and the displacement sub-control is added. The actuator 1 is always stopped in a zero-load state without the weight of the piston or grip acting on the test piece, and the test piece in the final state of the test can be recovered.

[Brief explanation of drawings]

The drawing is a block diagram showing the configuration of an embodiment of the present invention. 1...actuator, 2...servo amplifier, 3...
Servo valve, 4...Load cell, 5...Load amplifier,
6... Displacement detector, 7... Stroke amplifier, 8... Test waveform generator, 9... Zero load signal generator, 10... Displacement target value signal generator, S1... Changeover switch, S2
...Selection switch.

Claims (1)

[Claims] 1. In a material testing machine that applies a load to a test piece by an actuator controlled by a servo mechanism whose control amount is an arbitrary physical quantity related to the load on the test piece,
circuit means for forcibly setting the control amount of the servo mechanism as a load and setting the target value to zero when the test stop command is issued; and a sub for feeding back the detected displacement value of the actuator to the displacement target value when the stop command is issued. The actuator is equipped with circuit means for inserting a control loop into the servo mechanism, and when a test stop command is issued, the actuator performs both load control to make the load target value zero and displacement control to control the actuator to a predetermined target stop position. A test specimen protection stop device for a materials testing machine, characterized in that the device is configured to be driven by a control loop of a material testing machine.