JP3238991B2 - Electro-hydraulic material testing equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electro-hydraulic material testing apparatus for applying a hydraulic pressure to a test piece and electrically detecting a measured value to test the properties of various materials. The present invention relates to an electro-hydraulic material testing apparatus for testing a test piece in a plurality of negative feedback control modes by a machine.

[0002]

2. Description of the Related Art Generally, a material test is performed by selecting various negative feedback control modes by an operator and applying a load to a test piece in the selected mode. This negative feedback control mode includes modes such as displacement, elongation, and load.For example, when a test piece is chucked to an actuator of a test machine, the test is performed in a displacement negative feedback control mode. When switching to the negative feedback control mode, a complicated operation is required to avoid the shock on the test piece due to the level difference between the modes.

That is, as shown in FIG. 10, a signal generator 1, a position setting volume 2, and signals from displacement, elongation, and load detectors 3, 4, and 5 corresponding to a negative feedback control mode of each test. To the test piece TP via the adder 6.
Input to the servo valve 8 of the hydraulic control system of the actuator 7 that applies hydraulic pressure to the actuator 7, and selectively switches to a desired mode state by the test mode switch 9 so that the mode measurement value is electrically detected. It is composed. In the figure, reference numerals 10 and 11 denote an amplifier and an ammeter interposed in a signal line between the adder 6 and the servo valve 8, respectively.
Reference numerals 2, 13, and 14 denote sensor amplifiers interposed in signal lines between the detectors 3 to 5 and the test mode changeover switch 9, respectively.

Generally, a material testing apparatus using this kind of hydraulic pressure is in a state where the hydraulic pressure of the hydraulic pressure source does not act on the actuator 7, that is, during the non-use state, the center position of the spool of the servo valve 8 and the position of the actuator 7. When the pump of the hydraulic pressure source is driven and the hydraulic pressure is applied in such a state, a large displacement is instantaneously given to the actuator 7 depending on the position of the spool or the actuator 7, and at the same time, the Even if certain sensors 3 to 5 or test piece TP or other parts are destroyed or not destroyed, the test cannot be continued as it is,
Problems arise, such as replacing the test piece TP and performing the test again, mounting the test piece TP again, and re-adjusting the reference level from the sensor.

For this reason, in the conventional apparatus, when the use of the apparatus is started, the hydraulic pressure supplied to the servo valve 8 from the hydraulic pressure source is cut off in advance to switch to the displacement mode state.
A complicated operation of operating the position setting volume 2 to monitor the servo valve ammeter 11 to adjust the value to zero, and then applying hydraulic pressure to the servo valve 8 was required.

Therefore, conventionally, when the power switch of the apparatus is turned on, the displacement mode changeover switch is turned on in connection with the power switch, and the signal other than the signal generator is prevented from being input to the control system of the actuator. When a signal other than the generator is not input to the control system of the actuator, by configuring the hydraulic power source drive switch to be turned on, at the start and end of use of the device, without performing a complicated operation, Devices have been proposed which facilitate handling without giving use to test pieces and other components.

[0007]

In the above-mentioned conventional apparatus, the handling is easy without any trouble to the test pieces and other parts without complicated operation of the apparatus.
Only when the signal other than the signal generator is not input to the control system of the actuator, the drive switch of the hydraulic source is turned on and the hydraulic pressure from the hydraulic source acts on the actuator. It is supposed to be.

However, a relatively long time is required for the hydraulic pressure from the hydraulic pressure source acting on the actuator to stabilize, so that there is a problem that the test time for a test involving switching of the negative feedback control mode becomes long. Was.

Therefore, in view of the above-mentioned conventional problems, the present invention can perform the switching operation of the negative feedback control mode without obstructing the test pieces and others and with the hydraulic pressure applied, and is easy to handle. It is another object of the present invention to provide an electro-hydraulic material testing apparatus capable of shortening a time required for a test involving switching of a negative feedback control mode.

[0010]

In order to achieve the above object, an electro-hydraulic material testing apparatus according to the present invention is shown in FIG.
As shown in the basic configuration diagram of FIG. 1, in an electro-hydraulic material testing apparatus for testing a test piece TP in a plurality of negative feedback control modes by one testing machine, each is provided corresponding to each negative feedback control mode. output a plurality of negative feedback loop means 24 _{1-24 3} which are interconnected, a servo valve which is provided between the servo valve 8 point of interconnection with the hydraulic actuator 7 of the output of the negative feedback loop means of the plurality of Drive amplification means 25
Each negative feedback loop means, in addition to the control target signal,
A negative feedback summing means 24a ₁ negative feedback signal for each mode is applied, respectively, a position setting means 24b ₁ for setting a position signal applied to adjust its output signal to the negative feedback adder means, said negative feedback adder Signal gain adjusting means 24a provided before the means for adjusting the gain for the control target signal applied to the negative feedback adding means.
_2, the forward gain adjusting means 24a ₄ for adjusting the gain for the output signal of the negative feedback summing means disposed downstream of said negative feedback adder means, said position setting means, for controlling the signal gain adjusting means and forward gain adjusting means Control means 24b, when switching the negative feedback control mode, the control means sets the gain of the signal gain adjustment means of the negative feedback loop means before and after the switching to 0,
The gain of the forward gain adjusting means of the negative feedback loop means before switching is gradually reduced to 0, and the gain of the forward gain adjusting means of the negative feedback loop means after switching is gradually increased to a predetermined value. The position signal is set by the position setting means so that the magnitude of the negative feedback signal of the negative feedback loop means keeps a constant value.

[0011]

In the above construction, a plurality of negative feedback loop means are provided.
4 ₁ 24 ₃ of the interconnection point of the output to be connected to the servo valve drive amplifying means 25 provided between the servo valve 8 of the hydraulic actuator 7, when switching of the negative feedback control mode, the control means 24b is The negative feedback loop means before and after the switching, for example, the signal gain adjusting means of 24 ₁ and 24 ₂ , for example, the gains of 24a ₂₁ and 24a ₂₂ are set to 0, and the forward gain adjusting means 24a ₄₁ of the negative feedback loop means 24 ₁ before switching. gain negative feedback loop means 24 ₂ gain of the forward gain adjusting means 24a ₄₂ after the switching is gradually increased to a predetermined value with gradually decreasing to 0, the magnitude of the negative feedback signal of the negative feedback loop means after switching the time constant Position setting means 24 so as to hold the value.
and so as to set the position signal by b _1.

Therefore, the negative feedback signal before and after the switching, that is, the sensor signal, hardly changes, in other words, changes in the displacement, elongation or load acting on the test piece TP before and after the control mode switching. Therefore, even when the switching operation is performed by applying hydraulic pressure, unnecessary shock is not applied to the test piece.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 shows a schematic configuration of an embodiment of an electro-hydraulic material testing apparatus according to the present invention. In FIG. 2, reference numeral 21 denotes a host computer having a CRT, a keyboard, a storage device, and the like (not shown). Various constants for the material test set and various data obtained as a result of the material test are stored in the storage device. A control computer 22 includes a microcomputer (CPU) that operates according to a predetermined control program, and controls a test according to one selected from various test conditions set by the host computer 21.

The control computer 22 has a displacement negative feedback loop 24 ₁ and an extension negative feedback loop 24 via a common bus 23.
It is connected to the ₂ and the load negative feedback loop 24 ₃ for controlling the relationship between the respective and mutual negative feedback loop 24 _{1-24 3.}
Displacement signal from the displacement sensor negative feedback loop 24 _{1-24 3} (not shown), the load signal from the elongation signals and load sensors from elongation sensors are input, the deviation with respect to the control target signal by processing the input signal And outputs a deviation signal. The output of the negative feedback loop 24 _{1-24 3} is connected to the input of the servo valve drive amplifier 25 as a servo valve driven amplification means on which are interconnected, the servo valve drive amplifier 25 is a hydraulic actuator (not shown) by the output signal Drive the servo valve.

The hardware configuration of the negative feedback loop 24 _{1-24 3} are identical and shown in detail for the one 24 _1, are as shown in FIG. In other words, the negative feedback loop 24 ₁ digital signal processor (DSP) 24a
And a microcomputer (CPU) 24b as control means for controlling the DSP 24a. DSP
24a operates according to a control program stored in a ROM 24c connected thereto, fetches a signal from a sensor converted to a digital signal by an A / D conversion circuit 24d, processes this signal, and obtains a deviation from a control target signal. ,
Outputs a digital deviation signal. This deviation signal is D
After being converted into an analog signal by the / A conversion circuit 24e, it is sent to the servo valve drive amplifier 25. DSP24
a also has a common RAM 24 shared with the CPU 24b.
f is also connected.

On the other hand, the CPU 24b operates the R connected thereto.
Operate according to the control program stored in OM24g,
Bus 23 via interface (I / F) circuit 24h
Is connected to, on the basis of a command signal received from the negative feedback loop 24 ₁ via the bus 23 executes the command, captures a signal from the sensor converted to a digital signal by the A / D conversion circuit 24d, the signal to RAM24i The DSP 24a is controlled by writing and processing. A common RAM 24f shared with the DSP 24a is also connected to the CPU 24b.

The DSP 24a realizes a circuit configuration as shown in FIG. 4 by performing processing according to a control program stored in the ROM 24c. That, DSP24a includes an adder 24a ₁ as a negative feedback adder means for taking the difference between the sensor data Es corresponding to the sensor signal from the function data Ei and the A / D conversion circuit 24d corresponding to the target signal from the common RAM24f , Adder 2
A signal gain adjustment section 24a ₂ as a signal gain adjustment means for adjusting the function data Ei applied to 4a _1, sensor gain adjustment for adjusting the sensor data Es output of the A / D conversion circuit 24d to be added to the addition unit 24a ₁ Part 24a
_3, forward gain P (proportional) adjustment portion 24a ₄ of the forward gain adjusting means for adjusting the deviation data Ee corresponding to the deviation signal obtained at the output of the adder 24a ₁
When constitute the ID adjuster 24a ₅ for adjusting I (integral) D (derivative) before converting into an analog signal by the output data of the forward gain P adjuster 24a ₄ D / A converter circuit 24e.

[0018] Incidentally, the position data Ep common RAM which position setting portion 24b ₁ of the position setting means for configuring the CPU24b the addition section 24a ₁ is generated
24f. A second adder 27 is provided between the sensor amplifier 26 and the A / D conversion circuit 24d for zero adjustment of the sensor.
7, a zero adjustment signal generator 24b configured by the CPU 24b.
The adjustment signal from ₂ is supplied. Further, the sensor data Es output from the A / D conversion circuit 24d is fetched by the CPU 24b for monitoring and is stored in the RAM 24i.
Is stored. Furthermore, the deviation signal of the output of the D / A conversion circuit 24e is supplied to the servo valve drive amplifier 25.

The signal gain adjusting section 24a_Two, Sensory
In adjustment unit 24a_ThreeAnd forward gain P adjusting unit 24
a_FourGain coefficients Ki, Ks, and Kf, and ID adjustment unit 2
4a _FiveIs stored in the common RAM 2 by the CPU 24b.
4f, and the DSP 24a calculates these coefficients.
Read and multiply for gain adjustment, to get deviation
Addition / subtraction and ID operation are performed at high speed to obtain the deviation signal as D / A
It is sent to the input of the conversion circuit 24e. The above operation is A / D conversion
This is performed within the sampling interval by the conversion circuit 24d.
This allows everything to be configured digitally,
Significant improvement in S / N, which is a disadvantage of logs, can be achieved.
No adjustment, improved reliability, and lower cost can be realized.

Since the DSP 24a functions as shown in FIG. 4, a process performed according to a control program stored in the ROM 24c will be described below with reference to a flowchart of FIG. The DSP 24a is activated, for example, by turning on the power, and in the first step S1, the A / D conversion circuit 2
4d, the sampled sensor data Es is read and stored in the common RAM 24f. Then, the process proceeds to step S2, where the function data Ei stored in the data area of the common RAM 24f is read, and in the next step S3, the position data Ep stored in the data area of the common RAM 24f is read, and these data are shared. It is stored in the work area of the RAM 24f.
Then, in the next step S4, the coefficients Ki, Ks and Kf and the ID coefficient are read from the common RAM 24f, and this data is also stored in the work area of the common RAM 24f.

Then, the process proceeds to step S5, where the function data Ei and the sensor data Es are multiplied by the coefficients Ki and Ks, respectively, to adjust the gain, and the deviation between the gain-adjusted function data Ei and the sensor data Es is calculated. Obtain data and adjust position. By adding and subtracting the function data Ei, the sensor data Es, and the position data Ep, a deviation between the function data Ei and the sensor data Es is obtained to obtain the deviation data Ee and adjust the position. Further, after the gain adjustment P is performed by multiplying the deviation data Ee by a coefficient Kf, the ID of the gain-adjusted deviation data Ee is adjusted using an ID coefficient.

Next, the operation proceeds to step S6, in which the operation result is output and D / A conversion is performed by the D / A conversion circuit 24e.
Returning to step 1, the next sampling is performed and the above processing is repeated. As described above, the sensor signal is sampled every T seconds to obtain the sensor data Es, and all the calculations including the gain adjustment of each unit are completed and the deviation data is output during the period from the next to the next sensor data. Will be able to

The above-described operation is a test operation in the selected negative feedback control mode. In the case of switching the control mode of the above-described apparatus from displacement to elongation, the simplified diagram of FIG. This will be described below with reference to FIG.

When the negative feedback control mode is in the displacement mode, the gain coefficient K of the forward gain adjuster 24a ₄₁ is
is a predetermined value f ₁ is a predetermined gain coefficient Kf ₂ of forward gain adjustment section 24a ₄₂ is zero, which is in an open state. Now, the gains Ki ₁ and Ki _{2 of} the signal gain adjusters 24a ₂₁ and 24a ₂₂ are both set to 0,
Function data applied to the adder 24a ₁₁ and 24a ₁₂ are both a is 0. In this state, the adding unit 24a
Supplies the position data Ep ₁ of the specified size by CPU 24b ₁ to _11, monitor captures the CPU 24b ₁ sensor data Es ₁ is negative feedback signal at this time. As a result, although the deviation data Ee ₁ output of the adder a ₁₁ has become substantially zero, to switch processing while always maintaining this value.

Next, the value of the sensor data Es ₂ is
4b _2, and based on the monitored value of Es ₂ , the CPU 24 sets the deviation data Ee ₂ to 0.
b ₂ is to specify the position data Ep ₂ (-Es _2). Then gradually increasing the gain coefficient Kf ₂ of forward gain adjustment section 24a ₄₂ to a predetermined value, the gain coefficient Kf ₂ of forward gain adjustment section 24a ₄₁ gradually decreases to 0, switching to extend from the displacement of the negative feedback control mode but by Es ₂ are monitored at this time adjusts the position data Ep ₂ to maintain a substantially constant value, to avoid shock to the test piece.

The method of switching the negative feedback control mode from displacement to elongation, which has been schematically described above, is described by a displacement negative feedback loop 24 _1.
CP of the negative feedback loop 24 ₂ elongation and CPU 24b ₁ in
The process performed by U24b _{2 in} accordance with a predetermined control program will be described in detail with reference to flowcharts of FIGS.

In the flowchart of FIG. 7, the CPU 24b
₁ response to the start of the mode switching operation, in a first step S11 that determines whether or not there is a step-down command from the elongation negative feedback loop 24 _2, the determination is Y
Proceeds to step S12 when the ES reduces the gain coefficient Kf ₁ of forward gain adjustment section 24a ₄₁ by a predetermined value ΔKf _1. Note that the predetermined value ΔKf ₁ is a value for setting Kf ₁ to 0 at an N equal division ratio, and Kf ₁ / N = ΔKf ₁ . Thereafter, the flow returns to step S11 to wait for the next step-down command, and when there is a step-down command, the above-described operation is repeated.

On the other hand, in the flowchart of FIG.
24b ₂ is response to the start of the mode switching operation, in a first step S21 the read sensor data Es ₂ and holds it as an initial value Es _20. Thereafter, the process proceeds to step S22, where the CP of the displacement negative feedback loop 24 ₁ is set.
Sends a step-down command addressed to U24b _1, forward gain adjustment section 24a at the next step S23
₄₂ of the gain coefficient Kf ₂ by a predetermined value DerutaKf ₂ increases.
Note that the predetermined value ΔKf ₂ is a value that sets Kf ₂ to a predetermined value at N equal division ratios, and Kf ₂ / N = ΔKf ₂ . Then the process proceeds to step S24, where monitoring the value of the sensor data Es _2, in the next step S25, whether the monitor value Es ₂ has either increased relative to the initial value Es _20, or decreased, or equal Is determined. That is, Es
_It is determined whether ₂₀₋ Es ₂ = ΔEs ₂ is negative, positive, or zero.

[0029] When the determination in step S25 is increased, the steps from the supply to the adder 24a ₁₂ a predetermined value ÁEp ₂ subtracted value willing from the current position data Ep ₂ in step S26 as a new position data Returning to S24, the operations of steps S24 and S25 are repeated. On the other hand, when the determination in step S25 is a decrease, the process proceeds to step S27, where the position data E
to p ₂ a value obtained by adding a predetermined value ÁEp ₂ after supplied to the addition section 24a ₁₂ as new position data returns to step S24 to repeat the operations of steps S24 and S25.

[0030] Note that when the same determination in step S25, determines whether the gain coefficient Kf ₂ of forward gain adjustment section 24a ₄₂ becomes the specified value the routine proceeds to step S28, described above when this determination is NO returning to step S22 repeats the operation of step S22 and later, the negative feedback control mode switching operation When the determination in step S28 becomes a value that the gain coefficient Kf ₂ is designated the forward gain controller 24a ₄₂ becomes YES finish. At this time, it becomes a gain coefficient Kf ₁ are 0 forward gain adjustment section 24a ₄₁ of the displacement negative feedback loop 24 _1, negative feedback control mode is switched-out fully extended from the displacement. By the way, the speed at which the control returns from step S26, S27 to step S24 is linear because the control is linear.
It is determined by the stability condition of the system.

As described above, when the control mode is switched, the gain coefficient of the forward gain adjuster provided at the output of the adder of each system is increased or decreased by a predetermined amount, and the change in the sensor output at that time is monitored. The increase / decrease of the position signal applied to the adder so that the sensor output retains the initial value is automatically repeated until the gain coefficient of the forward gain adjuster reaches a predetermined value. In addition to being able to perform switching work, it is also possible to switch between different control loops accurately due to the characteristic error of the negative feedback control loop, and without shocks without requiring troublesome operations and without damaging the test specimen. Can be realized smoothly.

Further, as described above, displacement, since to be connected to the input of the servo valve drive amplifier 25 on the output of the negative feedback loop 24 _{1-24 3} elongation and load interconnected, Figure 9 as shown, each negative feedback loop 24 ₁
24 ₃ and when constituting each independent circuit board servo valve drive amplifier 25, between the substrates can be interconnected in a single signal line L, cost and structure becomes simple, structured surface This is advantageous in terms of reliability. Further, since the signal line between the negative feedback loop 24 _{1-24 3} and the servo valve drive amplifier 25 becomes low impedance, also it becomes excellent in noise resistance.

[0033]

As described above, according to the present invention, the displacement acting on the test piece before and after the control mode switching,
There is no change in the magnitude of elongation or load, and even if switching work is performed with hydraulic pressure applied, there is no problem by applying unnecessary shocks to test pieces and other parts, and the work is automatically performed with hydraulic pressure applied. Therefore, the handling is easy and the time required for the test involving the mode switching can be shortened.

[Brief description of the drawings]

FIG. 1 is a diagram showing a basic configuration of an electrohydraulic material testing apparatus according to the present invention.

FIG. 2 is a view showing the overall configuration of an electrohydraulic material testing apparatus according to the present invention.

FIG. 3 is a diagram showing details of a displacement negative feedback loop in FIG. 2;

FIG. 4 is a diagram showing a negative feedback loop formed by the DSP in FIG. 3;

FIG. 5 is a flowchart showing a process performed by the DSP of FIG. 3 so as to form the loop of FIG. 4;

FIG. 6 is a diagram for explaining how to switch the negative feedback control mode.

FIG. 7 is a diagram showing the operation performed to switch the negative feedback control loop.
9 is a flowchart illustrating a process performed by a middle CPU.

FIG. 8 is a diagram showing the operation performed to switch the negative feedback control loop.
9 is another flowchart showing the processing performed by the CPU in the middle.

FIG. 9 is a diagram for describing an advantage obtained by the configuration of FIG. 2;

FIG. 10 is a diagram showing an example of a conventional device.

[Explanation of symbols]

TP test piece 7 Actuator 8 Servo valve 24 _{1 to} 24 ₃ Negative feedback loop means (negative feedback loop) 24 a ₁ Negative feedback addition means (addition unit) 24 a ₂ Signal gain adjustment means (signal gain adjustment unit) 24 a ₄ Forward gain adjustment means (Forward gain adjustment unit) 24b Control unit (CPU) 24b ₁ Position setting unit (position setting unit) 25 Servo valve drive amplification unit (servo valve drive amplifier)

────────────────────────────────────────────────── ─── Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G01N 3/00-3/62 JICST file (JOIS)

Claims (1)

(57) [Claims] 1. An electro-hydraulic material testing apparatus for testing a test piece in a plurality of negative feedback control modes by a single testing machine, each of which is provided corresponding to each negative feedback control mode, and outputs are interconnected. A plurality of negative feedback loop means, and servo valve drive amplifying means provided between an interconnection point of the outputs of the plurality of negative feedback loop means and a servo valve of the hydraulic actuator. However, in addition to the control target signal, negative feedback addition means to which the negative feedback signal of each mode is respectively added, position setting means for setting a position signal applied to adjust the output signal to the negative feedback addition means,
A signal gain adjusting means provided before the negative feedback adding means for adjusting a gain for the control target signal applied to the negative feedback adding means; and a signal gain adjusting means provided after the negative feedback adding means for an output signal of the negative feedback adding means. Forward gain adjusting means for adjusting the gain, and control means for controlling the position setting means, the signal gain adjusting means and the forward gain adjusting means, and when the negative feedback control mode is switched, the control means controls before and after the switching. The gain of the signal gain adjusting means of the negative feedback loop means is set to 0, the gain of the forward gain adjusting means of the negative feedback loop means before switching is gradually reduced to 0, and the forward of the negative feedback loop means after switching is changed. The gain of the gain adjusting means is gradually increased to a predetermined value. An electro-hydraulic material testing apparatus, wherein the position signal is set by the position setting means such that the magnitude of the negative feedback signal of the return loop means is maintained at a constant value.