JPS6029717Y2 - Load testing machine - Google Patents

Description

[Detailed description of the invention] This invention is a load test in which a load is applied to a sample test specimen by controlling a fluid pressure actuator in a servo loop according to the difference between the output of a load signal source and the output of a load detection load cell. Regarding machines.

In this type of load testing machine, a reaction force detector such as a load cell is interposed between a load test object and an operating mechanism that directly applies a quadruple load to the load test object.

In addition, a signal corresponding to the quadruple load currently applied to the load test object from the reaction force detector and a signal for applying the quadruple load to the load test object are respectively input to the servo signal generator. I'm giving it to the edge.

The servo signal generator is configured to generate a signal corresponding to the difference between the two signals, and use this signal as a servo signal to operate the actuating mechanism to change the quadruple load.

If the two signals are not equal, the servo signal becomes zero, the operation of the actuating mechanism is stopped, and balance is maintained.

However, the output signal of the reaction force detector exhibits a sudden change when the load test object is ruptured due to an increase in the quadruple load on the load test object.

Therefore, when a break occurs, the signal difference between the two suddenly increases, and the servo signal suddenly changes in the direction of applying a quadruple load to the load test specimen.

As a result, the operating mechanism goes out of control, causing the problem of not only destroying the load test object but also, in the worst case, damaging or destroying the load test machine.

To solve this problem, conventionally, a limit switch or the like is provided during the stroke of the movement locus of the actuating mechanism to cut off or reduce the fluid pressure that operates the actuating mechanism, and to stop or stop the actuating mechanism. A pressure cut method was used.

However, in this method, the response characteristics to fracture of the load test specimen were poor, and a time delay of about 0.5 seconds occurred no matter what.

Therefore, at least complete or almost complete destruction of the load test specimen was caused, and important data such as the process of destruction of the load test specimen was often not collected.

Furthermore, a method of stopping a load testing machine by detecting a sudden change in the output of a load cell using a CR differential circuit or the like has been commonly used as a simple stopping means.

However, this method is designed to make an emergency stop in response to sudden changes in applied load in a static load testing machine that does not have a servo loop.

Therefore, in a load testing machine with a high-gain servo loop as described above, power supply noise generated as a disturbance in the high-gain servo loop and external noise superimposed on the signal cable connecting the servo circuit and the test drive device Against noise, such emergency stop means are completely useless.

For this reason, a problem has arisen in that a defective load outside the settings is applied to expensive sample specimens and load testing machines, resulting in damage to these.

The present invention was devised in view of these problems, and is a load test method that prevents damage or destruction of expensive load test specimens and load testing machines, and that allows data on the destruction of load test specimens to be easily obtained. The aim is to provide the opportunity.

Embodiments of the load testing machine according to the present invention will be described below with reference to the drawings.

FIG. 1 is a block circuit diagram.

As shown in the figure, a voltage signal e is applied to one input terminal of a servo amplifier 5VAl, which is an example of a servo signal generator.

This voltage signal e1 is applied to a signal from a signal generator SG2 via a resistor R1 to a servo valve SV, which is an example of a fluid pressure control mechanism to be described later, via a resistor R2.
This is a superimposed signal of the feedback signal from 4.

Note that the signal from the signal generator SG2 is a voltage signal for applying a load to the load test body 3.

On the other hand, the other input terminal of the servo amplifier SVA l has a voltage value + proportional to the load currently applied to the load test specimen 3 from the load cell L/C5, which is a reaction force detector described later. is given.

The servo amplifier 5VAi outputs a servo current, which is a servo signal, which increases or decreases in proportion to the voltage difference between the two pressure signals, e2.

In other words, the larger the difference between the two armies'JE"He2, the more
Both military pressure e1? As the difference in e2 becomes smaller, a decreasing servo current is output.

The degree of amplification of this servo amplifier SVA i is determined by the ratio of the resistors R1 and R2, that is, the ratio of R2/R.

The servo current is applied to the servo valve SV4 via a switch circuit section 6 that has a function of blocking the flow of this current.

This servo valve SV4 is controlled by a servo current, and supplies oil, which is a type of fluid, to the actuator 7, which is an example of an operating mechanism, in proportion to the amount of this servo current.

The actuator 7 is operated by changing the oil pressure of the actuator 7 with an amount of oil proportional to the amount of servo current.

A load cell L/C5, which is the reaction force detector described above, is interposed between the actuator 7 and the load test body 3.

In the above circuit, as mentioned above, the servo amplifier 5
Both forces e1. at the input end of VAl. The difference in e2 disappears and e□
When the condition = e2 is satisfied, the servo current becomes zero, and the operation of the actuator tough is stopped to maintain balance.

Further, a part of the feedback signal from the servo valve SV4 is given to the differentiating circuit section 8.

In this differential circuit section 8, as shown in FIG. 2, the load increases and the load test specimen 3 breaks, and the output voltage signal e2 from the load cell L/C5 changes rapidly, causing both Pressure e1. An impulse wave is generated when the difference in e2 becomes large and the servo current suddenly changes.

This generated impulse wave is amplified by an amplification circuit section 9 and is applied to a switch drive circuit section 10 that drives the switch circuit section 6 .

That is, the switch circuit section 6 is driven based on an impulse wave generated by a sudden change in the servo current to cut off the servo current.

According to this configuration, noise superimposed on the servo system power supply,
Output signal line of signal generator 2 and servo amplifier 1
The large amplitude change (surge) that occurs in the servo signal due to noise superimposed on these signal lines by routing the output signal lines at the test site is blocked by the switch 6, so the servo valve 4 There is no response to these noises.

That is, since the actuator 7 is stopped before the surge is applied to the test object, damage to the expensive test object 3 or damage to the servo mechanism can be effectively prevented.

Next, FIGS. 3 and 4 show these switch circuit sections 6,
An example of a specific circuit constituting the differentiating circuit section 8, the amplifying circuit section 9, and the switch driving circuit section 10 is shown.

FIG. 3 shows a specific circuit of the switch circuit section 6.
The reference numeral O12 in the figure indicates an input/output terminal corresponding to that in FIG.

The switch circuit section 6 includes a contact point 6A of a high-speed relay switch,
6B and a contact piece 6C.

The contact piece 6C of the switch circuit section 6 is normally connected to the contact point 6A, so that the servo current flows from the input terminal O to the output terminal P.

However, when the servo current suddenly changes, the contact 6C changes to
A and connected to the contact 6B, and the contact piece 6C is grounded.

As a result, the flow of the servo current is interrupted, and the operation of the actuator 7 is instantaneously stopped.

FIG. 4 shows specific circuits of the differential circuit section 8, the amplification circuit section 9, and the switch drive circuit section 10, and the symbol q in the figure indicates the input terminal corresponding to that in FIG. 1.

The servo current that changes suddenly due to breakage of the load test specimen 3 introduced into the input terminal q is connected to the capacitor C88A and the resistor y.

The signal is differentiated in the differential section composed of 8B, and a differential wave, that is, an impulse wave is formed.

The time constant of this differential portion varies depending on the fracture type of the load test specimen 3, but may be set to about 0.1 m5eC for metal materials, composite materials, and their structures.

Next, this impulse wave is transmitted to the transistor Tr□9T
r29 A? 9. In the widening section composed of B and the like, the width is widened and the waveform is formed.

This waveform-shaped impulse wave is applied to the gate G of the thyristor SCR10B to turn it on.

When the thyristor SCRI QB is turned on, the relay driving section 10A is operated, the contact piece 6C is connected to the contact point 6B, and the servo current is cut off.

If a high-speed relay switch constituted by the contacts 6A, 6B, the contact 6C, and the relay drive section 10A is used in this way, the servo current can be interrupted in about 5 to 1Q msec.

Note that it is also possible to use a semiconductor switching element instead of the high-speed relay switch.

In this case, it goes without saying that the circuit configuration changes depending on the semiconductor switching element.

In addition, in this embodiment, the servo signal was explained using a signal to increase or decrease the current, but the circuit configuration etc. may be changed appropriately to a signal based on an increase or decrease in voltage or a signal based on an increase or decrease in the number of pulses. Therefore, it is clear that the present invention is applicable.

In summary, the load testing machine of the present invention is characterized in that it is configured to detect a sudden change in the servo signal due to breakage of the load test object, etc., and promptly shut off the servo signal.

As a result, the operating mechanism can be stopped instantaneously via the fluid control mechanism, and damage or destruction of the load testing machine due to runaway of the operating mechanism can be prevented.

Further, complete or almost complete destruction of the load test specimen can be avoided as much as possible, and data on the process of destruction etc. can be easily collected.

Note that when many actuating mechanisms are used simultaneously, such as in a whole-aircraft suspension test, it is possible to effectively prevent unbalance of the airframe due to damage to the airframe or the load section.

Furthermore, since it detects sudden changes in servo signals, it can be configured to operate against spike noises coming from inside or outside the load testing machine. Provides sufficient protection for the body.

[Brief explanation of drawings]

Fig. 1 is a block circuit diagram showing one embodiment of the present invention;
The figure shows the change in servo current as the load test object breaks, and Figure 3 is a specific circuit diagram of the switch circuit shown in Figure 1.
FIG. 4 is a specific circuit diagram of the differentiator circuit section, amplification circuit section, and switch drive circuit section of FIG. 1. In addition, in the symbols used in the drawings, 1...
...Servo amplifier, 3...Load test specimen, 4...
... Servo valve, 6 ... Switch circuit section, 7 ... Actuator, 8 ... Differentiation circuit section, 9 ... Amplification circuit section, 10...Switch drive circuit section.

Claims (1)

[Scope of utility model registration request] A fluid pressure actuator is connected to the load test object via a load cell, and the difference between the load detection output obtained from the load cell and the load signal source output is amplified by a servo amplifier and sent as a servo signal to the servo valve of the fluid pressure actuator. In a load testing machine that performs closed loop control in which the fluid pressure actuator operates in accordance with the output of the load signal source, means for detecting a sudden change in the servo signal; A load testing machine characterized by comprising means for blocking a signal.