JPH0629720Y2 - Material testing machine - Google Patents

Description

Detailed Description of the Invention A. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a material testing machine for detecting two different physical quantities of a controlled object by a digital value and an analog value, and feeding back one of them as desired for testing.

B. 2. Description of the Related Art Conventionally, a fixed table and a crosshead that moves up and down relative to the fixed table are provided, and grips are attached to the fixed table and the crosshead, respectively, and a test piece is held between the grips to perform a test. Material testing machines are widely known. In such a material testing machine, a test pattern that loads the test piece while driving the crosshead at a constant speed, a test pattern that loads the test piece with a constant load speed, and a test pattern with a constant strain rate of the test piece The test is performed with a plurality of test patterns, such as a test pattern for loading a piece.

In a material testing machine that performs various tests with such a plurality of test patterns, conventionally, for example, a control circuit configured as shown in FIG. 3 is used.

In FIG. 3, the rotary encoder 1 directly connected to the motor MT for driving the crosshead detects the speed of the crosshead as a pulse train, and the load cell 2 attached to the crosshead detects the load applied to the test piece as an analog value. Further, the strain gauge 3 attached to the test piece detects the strain of the test piece as an analog value. Further, according to an input operation from the operation panel 4, a crosshead speed setting device 5 for setting a target speed of the crosshead, a load speed setting device 6 for setting a load speed, and a strain speed for setting a strain speed of the test piece. The setter 7 is provided in the control unit 100, and the set values from the setters 5 to 7 are set in accordance with the test patterns 1 to 7 above.
The detection outputs from the rotary encoder 1, the load cell 2 or the strain gauge 3 are compared to obtain a deviation, and the crosshead driving motor MT is drive-controlled according to the deviation.

That is, when the test pattern of is selected, the switch S
W1 is closed, and switch SW2 has a contact closed and b contact opened. The number of pulse trains corresponding to the target speed is output from the crosshead speed setter 5, and this pulse signal is output to the counter 8
It is input to the up terminal of. The pulse signal from the rotary encoder 1 is input to the down terminal of the counter 8. The count value of the counter 8 is converted into an analog signal by the D / A converter 9 and is passed through the amplifier 10 to the motor MT.
To the motor drive signal. As a result, the motor MT rotates so that the crosshead moves up and down at the set target speed, and the test piece is loaded.

When the test pattern of is selected, the switch SW1
Open, switch SW2, switch SW3, SW4 is b
The contact closes and the analog signal from the load speed setting device 6
The load detection analog signal output from the load cell 2 via the load amplifier 11 is input to the deviation device 12, and the deviation of both analog signals is taken. This deviation signal is multiplied by the gain in the gain setting unit 13 and sent to the motor MT via the amplifier 10. As a result, the crosshead is moved up and down so that the load applied to the test piece increases at the set load speed.

Similarly, for the test pattern of, the motor MT is driven according to the deviation between the analog signal from the strain rate setting device 7 and the strain detection analog signal from the strain gauge 3, and the crossing is performed so that the strain velocity becomes constant. The head is driven.

The up / down counter 8 and the D / A converter 9
The servo amplifier 200 is configured by the amplifier and the amplifier 10. 28 is an A / D converter for converting the outputs of the load amplifier 11 and strain amplifier 14 into digital values,
A CPU 24 performs various data processing based on the load signal and the distortion signal sent from the A / D converter 28.

C. DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention However, in such a control circuit, a digital port DP to which a pulse train is input and an analog port AP to which an analog signal is input are provided as input terminals of the servo amplifier.
And are required, and their configuration is complicated.

A technical problem of the present invention is to eliminate the analog port of a servo amplifier in a material testing machine that detects a physical quantity of a controlled object by a digital value (pulse train) and an analog value and selectively feeds back the detected quantity.

D. Means for Solving the Problems Referring to FIG. 1 showing an embodiment, the material testing machine according to the present invention solves the above technical problems by the following constitution.

The material testing machine according to the present invention includes an actuator MT that raises and lowers a crosshead to load a test piece, an encoder 1 that outputs a number of pulse trains according to the ascending and descending speed of the crosshead, and a load of the test piece that is detected. Detecting means 2 for outputting an analog signal according to a physical quantity such as stretch
(3), a first setter 21 that sets the number of pulses according to the target ascending / descending speed of the crosshead by an input operation, and a second setter 21 that sets a target value of a physical quantity such as load or elongation by an input operation. 22 (23).

Further, the deviation calculation means 101 for calculating the deviation between the target value set by the second setting device 22 (23) and the detection value detected by the detection means 2 (3) and the deviation calculation means 101 are used. Based on the deviation, it has a pulse number calculating means 102 for calculating the number of pulses according to the ascending / descending speed of the crosshead necessary to cancel the deviation.

Further, a selecting means SW5 for selecting one of the number of pulses set in the first setting device 21 and the number of pulses calculated by the pulse number calculating means 102, and this selecting means SW5.
Pulse generator 2 which outputs the pulse train of the number selected in 5.
5 and a servo amplifier 200 to which the pulse train from the pulse generator 25 and the pulse train from the encoder 1 are input, and a deviation between the two is taken, and a drive signal for driving the actuator MT is output at a rotation speed corresponding to the deviation. To do.

E. The physical quantity of the controlled object such as the load and strain of the test piece is detected by the detecting means 2.
(3) is detected as an analog value, and the elevation speed of the crosshead is detected by the encoder 1 as a digital value, that is, a pulse train. The analog value of the detected physical quantity is compared with the target value by the deviation calculating means 101 to calculate the deviation. The deviation is converted into the number of pulses by the pulse number calculating means 102, and the pulse generator 25 outputs the pulse train of that number and inputs it to the servo amplifier 200. The servo amplifier 200 takes a deviation between the pulse from the encoder 1 and the pulse from the pulse generator 25, and controls the speed of the actuator MT according to the deviation. Therefore, the servo amplifier 200 does not need an analog input port.

It should be noted that, in the above D and E for explaining the configuration of the present invention, the drawings of the embodiments are used to make the present invention easy to understand, but the present invention is not limited to the embodiments.

F. Embodiment An embodiment of the material testing machine according to the present invention will be described with reference to FIGS. 1 and 2. The same parts as those in FIG. 3 are designated by the same reference numerals for description.

The load cell 2 detects the load acting on the test piece and outputs an analog detection signal corresponding thereto, and the strain gauge 3 detects the strain of the test piece and outputs an analog detection signal corresponding thereto. The load amplifier 11 amplifies the analog detection signal of the load cell 2, the strain amplifier 14 amplifies the analog detection signal of the strain gauge 3, and the A / D converter 28 includes the amplifiers 11, 1
The amplified output of 4 is A / D converted. Rotary encoder 1
Outputs a number of pulse trains according to the rotation speed of the motor MT that moves up and down the crosshead, that is, according to the crosshead lifting speed.

The crosshead speed setter 21 stores the number of pulses corresponding to the target speed according to the crosshead target speed signal input from the operation panel 4. The load speed setting device 22 stores the speed of the load applied to the test piece as a digital value according to the load speed signal input from the operation panel 4. The strain rate setting device 23 stores the strain rate of the test piece as a digital value according to the strain rate signal input from the operation panel 4.
The CPU (Central Processing Unit) 24 obtains the speed of the load detected by the load cell 2 and calculates the deviation between this load speed and the load speed sent from the load speed setter 22. Then, the deviation of the calculated load speed, that is, the number of pulses corresponding to the ascending / descending speed of the crosshead necessary to cancel the difference between the target load speed and the actual load speed is calculated. C
The PU 24 similarly calculates the deviation of the strain velocity and the number of pulses corresponding to the deviation. Therefore, this CPU 24
The deviation calculating means 101 and the pulse number calculating means 102 are included.

The switch SW5 (selection means) selectively selects either one of the number of pulses set in the crosshead lifting speed setting device 21 and the number of pulses calculated by the CPU 24.
Send to 5. The pulse generator 25 outputs a pulse train of the number of input pulses.

The servo amplifier 200 has an up / down counter 8, a pulse train from the rotary encoder 1 is input to the down terminal, and a pulse generator 25 is input to the up terminal.
The pulse train from is input. Therefore, the counter 8
The count value of indicates the deviation between the actual speed of the crosshead and the command speed. The D / A converter 9 D / A converts the count value of the counter 8 and forms an analog signal according to the count value. This analog signal is amplified by the amplifier 10 and sent to the motor MT as a motor drive signal.

The operation of the material testing machine thus configured will be described.

When performing a test at a constant crosshead lifting speed, the switch SW5 is switched to the a contact side in conjunction with the test start operation, and the number of pulses set in the crosshead lifting speed setting unit 21 is input to the pulse generator 25. Pulse generator 2
5 inputs the pulse train of the number to the up terminal of the up / down counter 8. A pulse train from the rotary encoder 1 is input to the down terminal of the up / down counter 8, but no pulse is output from the rotary encoder 1 because the motor MT is stopped at the start of the test. Therefore, the counter 8 counts up with the pulse from the pulse generator 25, the analog motor drive signal obtained from the amplifier 10 via the D / A converter 9 increases, and the motor MT is accelerated. When the motor MT starts rotating, a pulse is output from the rotary encoder 1 and input to the down terminal of the counter 8. Rotary encoder 1
When the number of pulse trains from the pulse generator is higher than the number of pulse trains from the pulse generator 25, the counter 8 counts down and the motor MT decelerates. When both are equal,
The count value is held at a value corresponding to the set crosshead lifting speed, the motor MT rotates at a constant speed, and the crosshead moves up and down at the set speed.

When testing with a constant load speed, the switches SW3, SW4, and SW5 are switched to the b-contact side in conjunction with the test start operation. The CPU 24 calculates the actual load speed based on the load signal from the load cell 2. The target load speed set in the load speed setter 22 is compared with the actual load speed calculated by the CPU 24, and the deviation between the two is taken. CPU2
4 further calculates the number of pulses according to the crosshead lifting speed required to cancel the deviation. The calculation of the number of pulses is performed by the procedure shown in FIG.

In FIG. 2, first, in step S1, the load signal is read, and the actual load speed is obtained from the difference from the load signal previously read. In step S2, the deviation between the actual load speed and the target load speed set by the load speed setting unit 22 is obtained, and the deviation is multiplied by the gain in step S3. The gain is input from the operation panel 4, and an appropriate value is selected according to the rigidity of the material. In step S4, the number of pulses is obtained from the multiplication result obtained in step S3. The number of pulses calculated by the CPU 24 is input to the pulse generator 25 in step S5.

The pulse generator 25 inputs the number of pulse trains to the up terminal of the up / down counter 8. At the start of the test, the detected output from the load cell 2 is zero, and therefore the actual load speed is also zero. Therefore, since the CPU 24 obtains a signal corresponding to the load speed of the load speed setting unit 22 as a deviation, the number of calculated pulses is large and many pulses are input to the up-count terminal of the counter 8. Since the motor MT is stopped at this time, no pulse is input to the down terminal of the counter 8 and therefore the motor MT is accelerated. When the motor MT starts to rotate, the motor MT is decelerated or rotates at a constant speed in the same manner as described above, and the test piece is loaded at the set load speed.

When performing a test with a constant strain rate, switch SW3, SW
4 and SW5 are the same as the test with a constant load speed except that they are switched to the c-contact side.

In this way, the deviation between the target analog value and the actual detected analog value is converted into a specified number of pulse trains and input to the servo amplifier, regardless of the control target such as load or strain that is detected and fed back as an analog value. Therefore, only the pulse train input terminal DP needs to be provided in the servo amplifier, and the analog port, which has been conventionally required, is unnecessary, and the configuration is simplified.

The circuit for calculating the deviation of the analog amount and the calculating circuit for calculating the pulse number from the deviation may be configured in the form of hardware. Further, although the motor is used to raise and lower the crosshead, the present invention can also be applied to a material testing machine that raises and lowers the crosshead with a fluid actuator. In that case, an electro-hydraulic servo valve for driving and controlling the hydraulic actuator is used, and the electro-hydraulic servo valve is used by the output of the servo amplifier.
The hydraulic servo valve is controlled.

G. Effect of the Invention According to the present invention, the deviation between the target analog value and the actual detected analog value related to the controlled object is converted into a predetermined number of pulse trains and input to the servo amplifier. Only the input terminal needs to be provided, which simplifies the configuration.

[Brief description of drawings]

FIG. 1 is a block diagram showing the overall configuration of a material testing machine according to an embodiment of the present invention, FIG. 2 is a flow chart showing an example of processing procedure, and FIG. 3 is a block diagram showing a conventional example. 1: Rotary encoder 2: Load cell, 3: Strain meter 8: Counter 9: D / A converter 21: Crosshead speed setting device 22: Load speed setting device 23: Strain speed setting device, 24: CPU 25: Pulse generator 100 : Control unit 101: Deviation calculation means 102: Pulse number calculation means 200: Servo amplifier

Claims (1)

[Scope of utility model registration request] 1. An actuator for moving a crosshead up and down to load a test piece, an encoder for outputting a pulse train of a number according to the ascending / descending speed of the crosshead to be detected, and a physical quantity such as load or elongation of the test piece to be detected. Detecting means for outputting an analog signal according to, a first setter for setting the number of pulses according to the target ascending / descending speed of the crosshead by an input operation, and a target value for a physical quantity such as load or extension by an input operation Based on the deviation taken by the deviation setting means, a deviation setting means for taking a deviation between the target value set by the second setting set and the detection value detected by the detection means. And a pulse number calculating means for calculating the number of pulses according to the ascending / descending speed of the crosshead necessary to cancel this deviation, and the pulse number and the pulse number set in the first setter. Selecting means for selecting one of the pulse numbers calculated by the calculating means, a pulse generator for outputting the pulse train of the number selected by the selecting means, a pulse train from the pulse generator and a pulse train from the encoder , A servo amplifier that outputs a drive signal for driving the actuator at a rotation speed corresponding to the deviation.