JPS62267643A - Fatigue testing machine - Google Patents

Abstract

PURPOSE:To control so as to keep a load for working on a test piece constant, by supplying an error signal corresponding to the difference of a load signal for working the test piece and a reference signal, and an instruction signal corresponding to the sum of said error signal and the reference signal, to a servo-valve. CONSTITUTION:When a test piece 1 is attached between a load cell 2 and a frame 7, and a reference signal 16 corresponding to a test load condition being a target is generated by a reference signal generator 15, a fatigue testing machine starts to operate. An arithmetic unit 19 outputs the reference signal 16 as an instruction signal 20 to a servo-valve 9. As a result, a load works on the test piece 1 and a load signal 5 is transmitted to an error signal generator 17. In such a state, a difference between the reference signal 16 and the load signal 5 is calculated, an error signal 18 corresponding to this difference is transmitted to the arithmetic unit 19, and the arithmetic unit 19 stores this error signal 18. Subsequently, an instruction signal corresponding to the sum of the error signal and the reference signal is generated, and by this instruction signal, the servo-valve is operated.

Description

[Detailed description of the invention] [Industrial application field] This invention relates to a fatigue testing machine.

[Conventional technology]

FIG. 4 is a partial block diagram of a conventional fatigue testing machine shown in a catalog of Mtinis Japan Co., Ltd., for example. In fig.

(ri is the test piece which is the object of the test, (2) is the test piece (1
), a load cell that electrically detects the load acting on (3).
) is the load cell output, (4) is the amplifier that amplifies the load cell output, (5) is the amplified load signal, (6) is the load indicator, and (7) is the test piece (1) and load cell (2) attached. (8) is a hydraulic actuator that is fixed to the frame (7) and applies a load to the test piece, (9) is a servo valve that controls the operation of the hydraulic actuator (8), (10) is a hydraulic Hydraulic pressure generator (11) for operating the actuator (8) is the test piece (1
), a function generator that generates a command signal (described later) that sets the size of the load to be applied, the shape of the waveform, etc.;
12) is the above command signal, (13) is the command signal (12)
A controller that compares the load signal (5) with the command signal (12) and provides the signal described below to the servo valve (9) so that the load corresponding to the command signal (12) is applied to the test piece (1). is the servo valve operation signal.

The conventional fatigue testing machine is configured as described above, and when the test piece (1) is attached between the load cell (2) and the frame (7) and the function generator (11) is operated, the preset A command signal (12) with a constant amplitude and a constant shoulder wave number is generated, and this command signal (12) j
The controller (13) sends a servo valve operation signal (1) to the servo valve (9) to achieve the corresponding load, and the servo valve (9) receives this and sends this servo valve operation signal (1).
The hydraulic actuator (8) operates to apply a hydraulic pressure amount corresponding to (4) to the hydraulic actuator (8). Thereafter, the controller (13) continues to give a continuous correction signal to the servo valve (9) as a servo valve operation signal so that the difference between the command signal (12) and the load signal (5) is minimized, and a test with a constant load amplitude is performed. It is done.

A block diagram of the above control system is shown in FIG. 5, and is a so-called negative feedback type control system.

In addition, as is well known, the performance curve of the fatigue testing machine for this control system is given as the relationship between constant specimen displacement and repetition rate, as shown in Figure 6, once the capacity of the hydraulic pressure generator (1o) is determined. .

[Problems that the invention is intended to solve]

In conventional fatigue testing machines, cracks occur in the heat test piece (1) during the test at a constant repetition rate, the rigidity of the test piece (1) decreases, and the amount of deformation increases, resulting in the control shown in Figure 6. When the test piece enters the unstable region, there is a problem that the load acting on the test piece decreases, and if you try to set the decreased load to the initial target value, the load waveform becomes distorted, making it difficult to perform accurate fatigue tests. In addition, if you want to perform a test with high accuracy in such a case, it is necessary to readjust the function generator (11) and reduce the repetition rate.As a result, the test There was a problem that the efficiency deteriorated.

This invention was made to solve the above-mentioned problems, and once the command signal corresponding to the test load condition is set, the stiffness of the test piece remains stable even if it changes during the test. The test load value and load waveform will not change (
The purpose is to obtain a fatigue testing machine that can perform , tests.

[Means for solving problems]

The fatigue testing machine according to the present invention is configured such that the load value and load waveform acting on the test piece match the set test conditions.
A reference signal generator that generates a reference signal, an error signal generator that generates an error signal that corresponds to the difference between the load signal that corresponds to the load acting on the test piece and the reference signal, and the sum of the reference signal and error signal. The system is equipped with an arithmetic unit that generates a command signal to perform the operation.

[For production]

In this invention, by supplying an error signal corresponding to the difference between the above-mentioned load signal and the reference signal and a command signal corresponding to the sum of this error signal and the reference signal to the servo valve, the load acting on the test piece is constant. Control takes place.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a fatigue testing machine according to the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram partially showing an embodiment of the present invention, and (1) to (1G) are exactly the same as those shown in FIG.

(15) is a reference signal generator for generating a reference signal corresponding to the set test conditions. (16) is a reference signal generated by this reference signal generator, and (17) is a reference signal generated by amplifier (4). An error signal generator (1a) for comparing the loaded load signal (5) and the reference signal (16) and generating an error signal corresponding to the difference between them is generated by this error signal generator (17). error signal s
(19) is the reference signal (16) and error signal (18) mentioned above.
) and generates a command signal corresponding to the sum of these sums.
This is a command signal generated by one.

In the fatigue testing machine configured as described above, the test piece (1) is attached between the load cell (2) and the frame (7), and the reference signal (1) corresponding to the target test load condition is applied.
6) is generated in the reference signal generator (15), the fatigue tester starts operating.

In the first load, since the previous load signal (5) is unknown, the calculation device (one outputs the reference signal (16) as the command signal (20) to the servo valve (9). , a load acts on the test piece (ri), and a load signal (5) is transmitted to the error signal generator (17).The load applied to the test piece (1) mentioned above depends on the stiffness of the load system. The waveform and size of the standard signal (16) will not be the same depending on the performance of the hydraulic power source and the hydraulic power source, and the load will not be applied according to the test conditions.Next, the error signal generator (17) The difference between the reference signal (16) and the above-mentioned load signal (5) is calculated, and the corresponding error signal (18) is transmitted to the calculation device (19), which stores this error signal (18). do.

This completes the first loading process.

In the second load, the arithmetic unit (19) transmits the memorized sum of the first error signal (18) and the reference signal (16) to the servo valve (9) as a command signal (20). , a second load is performed. In this case, the command signal (20
) is the reference signal (16) and the first load error signal (
18), the reference signal (
16) is performed, and the load signal (5)
is transmitted to the error signal generator (17) in the same way as the first load, the difference with the reference signal (16) is calculated, and transmitted and stored as an error signal (18) to the arithmetic unit (19). The second loading process is completed. Thereafter, the load is repeated in the same way, and after the number of repetitions determined by the gain of the control system, the reference signal (1
6) Different loads are executed.

In addition, in a conventional fatigue testing machine, load control is performed by continuously modifying the command signal in real time, but in the fatigue testing machine of the present invention, the command signal (20) is corrected in one load.
Corrections will be made. FIG. 2 shows a block diagram of the control system of the fatigue testing machine according to the present invention, and FIG. 3 shows the correspondence of the above-mentioned signals. For example, by inputting a reference signal as shown in Fig. 3(a) into a fatigue tester, Fig. 3(1))
When a load signal like this is obtained, the error signal for the primary load is shown in Figure 3 (C), and the command signal is shown in Figure 3 (d).
It is set as follows. As described above, since control is performed based on the reference signal and error signal, the fatigue tester according to the present invention can control the amplitude-repetition rate characteristic without restrictions as shown in FIG.

In addition, in the above example, a control system was described in which the load acting on the test piece was kept constant, but the same effect as described above can be obtained even when the amount of deformation of the test piece or the amount of displacement of the hydraulic actuator is controlled to be constant. .

〔Effect of the invention〕

As described above, according to this output FJAζζ, there is a reference signal generator that generates a reference signal, and an error signal generator that generates an error signal corresponding to the difference iζ between the reference signal and the load signal.

Since we have installed a calculation device that generates a command signal corresponding to the sum of the error signal and the reference signal and operates the servo valve using this command signal, even if the stiffness of the test piece changes, the initialized load can be maintained It is possible to perform fatigue tests without changing the size or waveform, and has the effect of determining the fatigue properties of materials with extremely high accuracy.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a partial block diagram of an embodiment of the present invention, and FIG. 2 is a block diagram of its control system. FIG. 3 is a waveform diagram of signals generated in each part of FIGS. 1 and 2, FIG. 4 is a block diagram showing a partial block diagram of a conventional fatigue testing machine, and FIG. 5 is a block diagram of its control system. FIG. 6 is a performance curve diagram of a conventional fatigue testing machine. In the figure, (ri is the test piece, (2) is the load cell, (3 is
) is the load cell output, (4) is the amplifier, and (5) is the load signal. (6) is a load indicator, (7) is a frame, (8) is a hydraulic actuator, (9) is a servo valve, and (10) is a hydraulic pressure generator. (11) is the function generator, (12) is the command signal, (Ig) is the controller, (1 is the servo valve operation signal, (15) is the reference signal generator% (14) is the reference signal. (17) is the error The signal generator, (18) is the error signal, (1
One is an arithmetic unit, and (20) is a command signal. In addition, in FIG. 1, the same reference numerals indicate the same or equivalent parts. Figure 1-4

Claims (1)

[Claims] A load addition/detection system for applying a load to a test piece and generating a load signal corresponding to this load, a reference signal generator for generating a reference signal corresponding to set test conditions, and the load signal. and an error signal generator for generating an error signal corresponding to the difference between the reference signal and the reference signal, and generating a command signal corresponding to the sum of the reference signal and the error signal, and transmitting the command signal to the load addition/detection system. A fatigue testing machine characterized by being equipped with a computing device for supplying data to a computer.