JPH04301741A - Material testing machine - Google Patents

Abstract

PURPOSE:To stably control the levels of the upper and lower limit values of actual load to a specimen in the set levels of initial amplitude. CONSTITUTION:Set signals (a) from a set signal generating means 110 and signals (b) detected by a detecting means 100 are processed through a drive control means 120, so as to be applied to an actuator 8 thereafter, so that the load test of a specimen SP is carried out by the use of a specified amplitude and a specified frequency with the actuator 8 controlled by means of feedback operations. An upper and a lower limit value detecting means 130 detects the upper and lower limit values of the detecting means (b), and a difference signal output means 140 compares the upper and lower limit values of the set signal (a) with the upper and lower limit values of the detection signal (b) respectively, so that a difference signal is applied to the set signal generating means 110. By this constitution, the amplitude of the set signal (a) is so corrected that the physical quantity corresponding to the specimen comes to the value of setting.

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 particularly suitable for load testing a highly viscoelastic specimen such as rubber.

0002

2. Description of the Related Art FIG. 4 is a schematic diagram showing a conventional electro-hydraulic material testing machine. In FIG. 4, reference numeral 1 denotes a testing machine main body that applies a compressive load or a tensile load to a highly viscoelastic specimen SP such as rubber or soft plastic, and this testing machine main body 1 is equipped with a loading frame 2. The load frame 2 is composed of a pair of columns 4 erected on a base 3 and a crosshead 5 attached to the columns 4 so as to be movable up and down. An upper jig 6 is attached to an intermediate portion of the crosshead 5 in a suspended state via a load cell 7. Note that 4a is a cross yoke horizontally suspended at the upper end of the support column 4.
It is

[0003] Inside the base 3, a hydraulic cylinder type actuator 8 for loading is installed in alignment with the axis of the upper jig 6. A lower jig 9 is attached to the tip of the piston rod 8a of the actuator 8, and a specimen SP is set between the lower jig 9 and the upper jig 6. 10
is a servo valve that controls hydraulic oil supplied to the actuator 8.

The feedback control system of the testing machine main body 1 is as follows:
A setting signal generator 11 that generates a setting signal a of any amplitude and arbitrary frequency (50 to 300 Hz or more), an amplifier 12 that amplifies the load signal b detected by the load cell 7, and a setting signal a and a detection signal. The servo amplifier 14 includes an adder 13 that calculates the deviation from the deviation signal c, and a servo amplifier 14 that amplifies this deviation signal c and applies it to the servo valve 10.

In the conventional material testing machine configured as described above, when a setting command suitable for testing the specimen SP is input to the setting signal generator 11, the setting signal generator 11 outputs a signal of a predetermined frequency and a predetermined amplitude. A setting signal a is generated, and this setting signal a is input to the adder 13. The adder 13 calculates the deviation between the setting signal a and the detection signal b, and the deviation signal c is amplified by the servo amplifier 14 and input to the servo valve 10. The servo valve 10 supplies hydraulic oil at a flow rate proportional to the signal to the actuator 8, thereby causing the actuator 8 to reciprocate at a cycle and stroke according to the set signal, thereby moving the specimen between the upper and lower jigs 6 and 9. S
Test the specimen SP by repeatedly applying a load to P.

[0006]

[Problems to be Solved by the Invention] By the way, since a highly viscoelastic specimen such as rubber has small stress and is easily deformed, there is a difference between the setting signal a and the detection signal b as shown in (a) in FIG. As shown in , a phase delay corresponding to ψ occurs. Along with this, the deviation signal c also oscillates as shown in FIG. 5(b), and the actual load applied to the specimen SP deviates from the initial set load. In other words, the upper and lower limit levels of the detection signal (actual load signal) change as shown by the broken line in FIG. 5(a) due to the deviation signal with the waveform shown in FIG. 5(b), and the load changes at the set amplitude level. I will not be able to take the test. Furthermore, when the phase delay becomes large and approaches 180°, there is a problem that feedback control of the testing machine itself becomes impossible.

An object of the present invention is to provide a material testing machine that can stably control the upper and lower limit levels of the actual load on the specimen to the initially set amplitude levels.

[
0008

[Means for Solving the Problems] The present invention will be explained with reference to FIG. 1, which is a diagram corresponding to claims. a detection means 100 that generates a setting signal a of arbitrary amplitude and an arbitrary frequency, and a drive control means 120 that drives and controls the actuator 8 based on a deviation signal between the setting signal a and the detection signal b. Applicable to material testing machines. The above purpose is to detect the upper and lower limit values of the detection signal b, and to compare the upper and lower limit values of the detection signal b with the reference upper and lower limit values of the setting signal a, and to detect the difference between the upper and lower limit values of the setting signal a. This can be achieved by having a difference signal output means 140 for outputting a signal, and adding this difference signal to the setting signal generating means 110 to correct the upper and lower limit values of the setting signal a.

[0009]

[Operation] When the actuator 8 starts operating in response to the setting signal a from the setting signal generating means 110, the upper and lower limit value detecting means 130 detects the upper and lower limits of the amplitude from the detection signal b. The difference signal output means 140 compares the upper and lower limit values of the detection signal b with the reference upper and lower limit values of the setting signal a, and inputs the difference signal to the setting signal generating means 110. This makes it possible to modify the amplitude of the setting signal a and apply a desired load to the specimen SP.

0010

Embodiment FIG. 2 is an overall configuration diagram showing an embodiment of the present invention. In the figure, the same parts as in FIG. 4 are given the same reference numerals, and a description of the configuration thereof will be omitted, and the parts different from FIG. 4 will be explained with emphasis.

As is clear from FIG. 2, the difference from FIG. 4 is that the setting signal generator 11 generates an initial setting signal a of a predetermined amplitude and a predetermined frequency set in response to a setting command from an operator or the like. The upper limit value Psr and the lower limit value Pdr are based on the upper and lower limit values of the amplitude of this setting signal a.
The upper and lower limit value detection circuit 15 detects the upper limit value Psb and the lower limit value Pdb of the detection signal b, and the upper limit value detection circuit 15 corresponding to the initial setting signal a from the setting signal generator 11 is provided. , lower limit values Psr, Pdr, and upper and lower limit values Psb, Pd detected by the upper and lower limit value detection circuit 15
a comparison circuit 1 that compares the difference between the two and generates a signal for controlling the amplitude of the setting signal from the difference, and outputs the signal to the setting signal generator 11;
It is located where 6 is located.

Next, the operation will be explained. When the initial setting signal a generated from the setting signal generator 11 is input to the servo valve 10 through the adder 13 and the servo amplifier 14, the servo valve 10 supplies the actuator 8 with hydraulic oil at a flow rate proportional to the signal. . As a result, the actuator 8 starts reciprocating motion with a cycle and stroke according to the initial setting signal a, and repeatedly applies compressive and tensile loads to the specimen SP. The load applied to the specimen SP due to the reciprocating motion of the actuator 8 is detected by the load cell 7, and its detection signal b is input to the adder 13 and the upper and lower limit value detection circuit 15. The adder 13 calculates the deviation between the setting signal a and the detection signal b, and inputs the deviation signal c to the servo valve 10 through the servo amplifier 14.

On the other hand, in the upper and lower limit value detection circuit 15, for example, the upper limit value Psb of the amplitude of the detection signal b is detected every cycle of the detection signal b.
and the lower limit value Pdb are detected and output to the comparison circuit 16. In the comparison circuit 16, the upper and lower limit values Psb of the detection signal b,
Standard upper and lower limit values Ps corresponding to Pdb and initial setting signal
By comparing r and Pdr, the upper limit difference signal S1
and a lower limit difference signal S2. When the upper and lower limit difference signals S1 and S2 are input to the setting signal generator 11, the upper and lower limit levels of the amplitude of the setting signal a to be generated are controlled to increase or decrease.

That is, since the difference signal between the initial setting signal a and the detection signal b becomes a deviation signal with a waveform as shown in FIG. 5(b), the detection signal b changes to the broken line in FIG. When the waveform shown in FIG. , the amplitude of the setting signal a to be outputted from now on is corrected according to the difference signal as shown by the broken line in FIG. Therefore, if the corrected setting signal a is input to the servo valve 10 through the adder 13 and the servo amplifier 14 as shown by the broken line in FIG. 3 and the actuator 8 is operated, the detection signal b detected by the load cell 7 is
As shown in FIG. 3, the waveform corresponds to the initial setting signal (corresponding to the waveform shown by the solid line in FIG. 3), and the actual load can be stably controlled to the initially set amplitude level.

Furthermore, if the phase delay between the setting signal a and the detection signal b approaches 180° due to the properties of the specimen SP, the deviation signal c between the two will have a waveform opposite to that shown in FIG. 5(b). However, in this case, if the amplitude of the setting signal a is corrected in the direction of decreasing it, contrary to the above case, a stable load test in which the actual load matches the initial setting amplitude level becomes possible.

In this embodiment, even when a large phase delay occurs between the setting signal and the detection signal during feedback control in a load test of a highly viscoelastic specimen such as rubber, the actual load on the specimen is maintained. The upper and lower limit levels do not fluctuate and can be stably controlled to the initial set level. In addition, the amplitude of the initial setting signal is adjusted by increasing or decreasing according to the difference between the lower limit value of the initial setting signal standard and the upper and lower limit value of the detection signal.
Stable amplitude control and feedback control are possible regardless of the magnitude of phase delay.

In the above embodiment, the case of load control has been described, but the same can be applied to displacement control. Furthermore, the present invention can also be applied to tests in which torque, acceleration, and speed are controlled in a sinusoidal manner.

In the above embodiment, the load cell 7 serves as the detection means 100, the setting signal generating device 11 serves as the setting signal generating means 110, and the servo valve 10, amplifier 12, adder 13 and servo amplifier 14 serve as the drive control means 120. ,
The upper and lower limit value detection circuit 15 constitutes upper and lower limit value detection means 130, and the comparison circuit 16 constitutes difference signal output means 140, respectively.

[0019]

[Effects of the Invention] As explained above, according to the present invention, the amplitude of the setting signal is corrected by the difference signal between the reference upper and lower limit values of the setting signal and the upper and lower limit values of the detection signal indicating various physical quantities. Therefore, the upper and lower limit levels of the physical quantity can be stably controlled to the initial set amplitude level regardless of the phase difference between the set signal and the detected signal fed back.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a material testing machine corresponding to the claim.

FIG. 2 is an overall configuration diagram showing an embodiment of the present invention.

FIG. 3 is a waveform diagram for explaining the operation in this embodiment.

FIG. 4 is a configuration diagram of a conventional material testing machine.

FIG. 5 is a waveform diagram for explaining conventional operation.

[Explanation of symbols]

SP specimen 1　Testing machine main body 2 Load frame 7 Load cell 8 Actuator 10 Servo valve 11 Setting signal generator 12 Amplifier 13 Adder 14 Servo amplifier 15 Upper and lower limit value detection circuit 16 Comparison circuit 100 Detection means 110 Setting signal generation means 120 Drive control means 130 Upper and lower limit value detection means 140 Difference signal output means

Claims (1)

[Claims] [Claim 1] An actuator that loads a specimen;
a detection means for detecting a physical quantity that changes when the specimen is loaded; a setting signal generating means for generating a setting signal of arbitrary amplitude and arbitrary frequency; and a deviation signal between the setting signal and the detection signal of the physical quantity. A material testing machine having a drive control means for driving and controlling an actuator, upper and lower limit value detection means for detecting upper and lower limit values of the detection signal, and a reference for the upper and lower limit values of the detection signal and the setting signal, and a difference signal output means for comparing the difference signal with a lower limit value and outputting the respective difference signals, and correcting the upper and lower limit values of the setting signal by adding the difference signal to the setting signal generating means. material testing machine.