JPS623640A - Load tester - Google Patents

Abstract

PURPOSE:To improve test efficiency by performing correction in accordance with the result of comparison between load data and detection data of a physical quantity acting upon a sample body resulted from preceding load data. CONSTITUTION:The first load data is read out from a RAM 13 to drive a servo actuator 21. The data value at this time is stored in the first buffer of the RAM 13. The load which acts upon a sample body W by driving of the actuator 21 is detected by a load cell 4, and a detection signal (s) is stored in the second buffer of the RAM 13 as detection data. Contents of the first and the second buffers are compared with each other, and the difference is stored in the RAM 13 as a correction value. Though the second load data is read out and outputted next, the value obtained by correcting the read-out value with the correcting value is outputted actually as load data. Since the magnitude of an operation signal (m) supplied to the actuator 21 is always corrected independently of the transfer characteristic so that detection data of the same value as load data in the RAM 13, is always obtained it is unnecessary to check the transfer characteristic before-hand, and the test efficiency is improved.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a load testing machine that converts load data output from a computer into analog and uses it as an operating signal for a loading mechanism, and specifically relates to a structural testing machine. .

This article relates to a testing machine used as a fatigue testing machine, etc.

<Prior Art> Load testing machines such as structural testing machines and fatigue testing machines whose main control mechanism is a computer have already been widely put into practical use. In general, in such a load testing machine, preset load waveform data is output from a combiator moment by moment, and the load data is converted into an analog signal by a D-A converter and then supplied to the load mechanism. give a load to. Detection signals of physical quantities related to loads actually acting on the specimen, such as load and displacement, are digitized by an AD converter and input into a computer.

<Problems to be Solved by the Invention> By the way, in the above-mentioned load testing machine, when comparing the load waveform data output from the computer and the detected data taken into the computer, the detected data is higher than the output data. It is generally smaller than. In structural tests and fatigue tests, it is the above-mentioned detection data that is important for analysis, and it goes without saying that it is undesirable for the load actually acting on the specimen to be unintentionally reduced. Conventionally, as a countermeasure against this, prior to testing, it was necessary to load the specimen, investigate the characteristics of the transmission system including the specimen, and determine the data to be output based on the results. There wasn't. However, if the characteristics of the system change during the test, there is a problem in that even if the above measures are taken, the desired load cannot be applied to the specimen.

The present invention has been made in view of the above, and is a testing machine that converts load data output from a computer into analog to obtain operating signals of a load mechanism. The purpose of the present invention is to provide a load testing machine that can always apply a desired amount of load to a specimen even if the characteristics of the system change.

Means for Solving Problems〉 As shown in the basic conceptual diagram in Fig. 1, the load tester of the present invention converts load data outputted from a computer every moment into D-
The operation signal m of the load mechanism 2 is converted into analog by the A converter 1.
At the same time, the detection signal S of the physical quantity related to the load actually acting on the specimen W was digitized by the A-D converter 3 and fed into the computer. A first buffer a that stores the latest load data, and a second buffer that stores digital conversion data of the detection signal S of the physical quantity acting on the specimen W based on the operation signal m based on the contents of the first buffer a. A buffer b is provided. It also includes a comparing means C for comparing the contents of the first and second buffers a and b, and a third comparing means C for storing the comparison results.
A buffer d is provided. And this third buffer d
Based on the contents of , the load data to be supplied to the DA converter 1 and converted into analog data is corrected by the correction means e.

Effect> The load data supplied to the D-A converter 1 is always corrected based on the comparison result between the previous load data and the detected data of the physical quantity actually acting on the specimen W based on the load data. Therefore, physical quantities of the desired magnitude always act on the specimen W, regardless of the characteristics of the system, and the desired purpose can be achieved.

<Example> Embodiments of the present invention will be described below based on the drawings.

The computer is CPU II, ROM12. Consists of RAM 13 and input/output port 14, etc.
DA converter 1 and AD converter 3 are connected via. The DA converter 1 converts the load data output from the computer into analog form and outputs the analog data, and the output signal is provided as the operation signal m of the electro-hydraulic servo actuator 21. The servo actuator 21 is driven according to the magnitude of this operation signal m, and can apply a load to the specimen W.

The physical quantity related to the load acting on the specimen W, for example, the load is
is detected by the load cell 4, and its detection signal S is A-
It is configured to be digitized by a D converter 3 and input into a computer as detection data.

A program to be described later is written in the ROM 12 of the computer, and the RAM 13 has an area for storing momentary digital data (load data) of the load waveform to be output, and an area for sequentially storing the aforementioned detection data. In addition, areas serving as first to third buffers, which will be described later, are set.

Next, we will discuss the effect. FIG. 3 is a flowchart showing the program written in the ROM 12.

When the test is started, load data stored in the RAM 13 in advance is read out in order from the first load data, a correction value d is added to the value, and the resultant value is supplied to the DA converter 1.

That is, first, the first load data is read out, and the value is supplied to the DA converter 1 to be converted into an analog value, and the servo actuator 21 is driven. At this time, the value for the load data is stored in the first buffer. The load acting on the specimen W by driving the servo actuator 21 is detected by the load cell 4, and the detection signal S is A-
It is digitized by the D converter 3 and outputted as detection data A'.
It is stored in the data area in AM13 and also in the second buffer. and the first and second
The contents of the buffers are compared, and the difference A-A' is stored in the third buffer as the correction value d.

Next, the second load data is read out and output for analogization, but at this time, the value actually output as load data is the read value plus the content d of the third buffer. Hereafter, the third. The fourth load data is also always corrected by the difference d between the load data actually output last time and the load actually acting on the specimen W based on that data, that is, the detected data, and then output.

Therefore, regardless of the transmission characteristics of the system including the specimen W, the operating signal "m" supplied to the servo actuator 21
The magnitude of is always corrected so that detected data having the same value as the load data preliminarily set in the RAM 13 is obtained.

In the above embodiments, the load was selected as the physical quantity related to the load, but it goes without saying that any physical quantity such as displacement may be selected as the physical quantity.

Effects> As explained above, according to the present invention, 1. The load data that should be analogized by the D-A converter 1 and used as the operating signal m of the load mechanism 2 is always corrected based on the comparison result between the load data output last time and the output data at that time. , for the specimen W, regardless of the characteristics of the system,
A load of the same value as the preset load data is always applied, and a desired structural test or fatigue test can be performed. Moreover, it is not necessary to investigate the transfer characteristics of the system including the specimen in advance, and the test efficiency can be improved.

[Brief explanation of the drawing]

Figure 1 is a basic conceptual diagram showing the configuration of the present invention, Figure 2 is a block diagram showing the configuration of an embodiment of the present invention, and Figure 3 is the ROM.
12 is a flowchart showing a program written in 12. 1...D-A converter 3...A-D converter 4...Load cell 11...CPU 12...ROM 13...RAM 14...I/O port

Claims (1)

[Claims] D-A load data outputted from the computer every moment
In a testing machine in which an operating signal of a load mechanism is obtained by converting it into an analog signal using a converter, and a detection signal of a physical quantity related to a load actually acting on a specimen is digitized by an A-D converter and input into the computer, a first buffer that stores the latest load data supplied to the D-A converter;
a second buffer that stores digital conversion data of the physical quantity acting on the specimen according to an operation signal based on the contents of the first buffer; and a comparison means that compares the contents of the first and second buffers; A load testing machine characterized by comprising: a third buffer for storing the comparison result by the comparison means; and a correction means for correcting load data to be converted into analog next based on the contents of the third buffer.