JP3499507B2 - Material testing machine - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a material testing machine capable of coping with a sudden reaction of a test piece subjected to a material test.

[0002]

[Related Background Art] A material testing machine applies a compressive load or a tensile load to a test piece,
It measures the elongation (displacement) of the test piece caused by this, and is configured to include a load sensor and an elongation sensor. In general, for example, as shown in FIG. 4, after the sensor output consisting of the load or elongation measured by the sensor 1 is amplified by the preamplifier 2, a preset measurement is made by the output amplifier 3. Amplification is performed at an amplification factor (magnification) corresponding to the range, the amplified output is converted into a digital value through the A / D converter 4 having a predetermined number of bits, and then the digital value is taken into the controller 5 including a microprocessor and a sequencer. , Is configured to acquire the measurement data.

In particular, the output amplifier 3 is constructed so that its amplification factor (measurement range) is variably set under the control of the amplification factor setting unit 6, and is switched and set under the instruction of the controller 5, for example. By setting the amplification factor of the output amplifier 3 according to a command from the output switching device (switch circuit) 7, an amplified output corresponding to the full scale of the A / D converter 4 is obtained.

[0004]

By the way, in the measurement system configured as described above, for example, as shown in FIG. 5, the measurement data (digital value) obtained through the A / D converter 4 has a predetermined scale range. It is necessary for the controller 5 to determine whether it is within the (measurement range) [step S1]. If the measured data is out of the scale range, an instruction to switch the amplification factor (measurement range) of the output amplifier 3 is issued [step S
2], it is determined whether or not the output selector (switch circuit) 7 has been driven and the measurement range (amplification factor) thereof has been changed [step S3]. Then, it is checked again whether the measurement data obtained from the A / D converter 4 is within a predetermined scale range [step S1], and the sensor value is acquired [step S4]. As a result, it becomes possible to acquire a digital conversion value having a high resolution corresponding to the output level of the sensor 1 as the measurement value.

However, depending on the test piece, the reaction due to the applied load changes abruptly. In such a case, if the amplification factor (measurement range) of the output amplifier 3 is switched according to the measurement data acquired by the controller 5, the switching of the amplification factor may not follow the change in the sensor output. If the switching timing is missed, there is a possibility that measurement data may be missed.

The present invention has been made in view of the above circumstances, and an object thereof is to make it possible to reliably obtain a digital conversion value corresponding to an output level of a sensor as a measurement value with high resolution. It is to provide a material testing machine equipped with a system.

[0007]

In order to achieve the above-mentioned object, a material testing machine according to the present invention comprises a sensor for measuring a load or elongation applied to a test piece and an amplification of preset measurement ranges different from each other. A plurality of output amplifiers for amplifying the outputs of the sensors at a rate, and a multi-channel type A for obtaining digital conversion values respectively corresponding to the amplified outputs of these output amplifiers and selectively outputting the digital conversion values. A / D converter and the A / D converter by switching the channel of the A / D converter according to the output of the A / D converter.
And a controller for selecting a digital conversion value acquired from the converter.

That is, the material testing machine according to the present invention comprises a plurality of output amplifiers whose amplification factors are fixedly set according to a plurality of measurement ranges (measurement magnifications) different from each other. Measured data obtained from the sensor are amplified respectively to obtain a plurality of amplified outputs, and these amplified outputs are digitally converted through the A / D converter and selectively acquired by the controller. By eliminating the need to switch the amplification factor of each of the output amplifiers, the digital conversion value in the measurement range corresponding to the output level of the sensor is obtained as the measurement value with good resolution.

In particular, the controller compares the output of the A / D converter with preset upper and lower limits to control channel switching of the A / D converter ,
The output (digital conversion value) of the A / D converter is the upper limit
When the value exceeds the value, the output amplification with the amplification factor lowered by one step
The channel of the converter and select the output of the A / D converter.
If the force (digital conversion value) falls below the above lower limit,
The measurement range is automatically switched by selecting the channel of the output amplifier whose amplification factor is increased by one step, and one of the plurality of output amplifiers whose amplification factor is fixed according to the measurement range is selected. Before the maximum measurement value of the measurement range is associated with
About 50% of the full scale of the A / D converter (below
Set as a range from the limit value to about 95% (upper limit value)
The feature is that the digital conversion value in the measured scale is obtained with high accuracy.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION A measuring system having a characteristic structure of a material testing machine according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram of a measurement system in this material testing machine, 11 is a test piece (not shown)
It is a sensor including a load cell and the like for detecting a load applied to the. The output of the sensor 11 is taken out via a preamplifier 12 as a so-called sensor amplifier and guided to an output amplifier 13. However, in this material testing machine, a plurality of output amplifiers 13a, 13b, in which the amplification factors specified by the respective measurement ranges are fixedly set, corresponding to the respective preset plurality of different measurement ranges. 13n are provided in parallel, and the sensor output detected through the preamplifier 12 is amplified by each amplification factor.

On the other hand, each of these output amplifiers 13a, 13
The A / D converters 14 for inputting the amplified outputs b, 13n respectively are of a multi-channel type, and the amplified outputs obtained from the output amplifiers 13a, 13b, 13n are respectively digital values of a predetermined number of bits. Convert to. Then, it receives a selection signal from the controller 15 including a microprocessor, a sequencer, etc., selects a channel, outputs the digital conversion value of the selected channel to the controller 15, and the controller 15 acquires this as the measurement data. ing.

Incidentally, the measurement range (measurement magnification) of the sensor output in the controller 15 is, for example, (× 1),
(× 2), (× 5), (× 10), (× 20), (× 50), (× 10
0), (× 200), the plurality of output amplifiers 13a, 13b, to 13 are set.
The amplification factor set for n is set so that the maximum measurement value in each of the above measurement ranges becomes the full scale FS of the A / D converter 14. Specifically, in the above example, the amplification factor in the maximum measurement range (× 200) is [1].
, The amplification factor in the minimum measurement range (× 1) is set as [200].

Further, the controller 15 has an upper limit value judgment function 15a for comparing the digital value given from the A / D converter 14 with its upper limit value and a lower limit value judgment function 15b for comparing it with the lower limit value, and further, these judgments are made. Function 15a,
An output control function 15c for selectively switching the channel of the A / D converter 14 according to the comparison result by 15b is provided. Specifically, the upper limit determination function 15a
When the digital value obtained from the / D converter 14 exceeds, for example, 95% of the full scale, a signal for increasing the measurement range by one step is output, and the lower limit value determination function 1
When the digital value obtained from the A / D converter 14 is, for example, less than 50% of the full scale, 5b outputs a signal that lowers the measurement range by one step. Then, the output control function 15c is configured to determine each of these determination functions 15a, 15
The channel of the A / D converter 14 is switched and set according to the comparison result from b and the currently set measurement range, and when the digital output value is within the measurement range, this is acquired as measurement data. Is configured.

According to the measurement system thus constructed, each of the output amplifiers 1 as shown in FIG.
3, 13b to 13n respectively amplify the sensor output at an amplification factor fixedly determined in advance, and the A / D converter 1
Reference numeral 4 inputs these amplified outputs to the respective channels to obtain their digital conversion values. Then, the controller 15 that obtains the digital conversion value of the one channel from the A / D converter 14 determines whether the digital conversion value is within the measurement range defined by the upper limit value and the lower limit value described above. If it is out of the measurement range, the channel of the A / D converter 14 is switched to obtain a digital conversion value within the full scale.

Therefore, according to the measurement system constructed as described above, whether the digital conversion value obtained from the A / D converter 14 is included in the predetermined measurement scale in the controller 15 as shown in FIG. 3, for example. Whether or not it is judged [Step S11], and when it is out of the measurement scale, the channel of the A / D converter 14 is simply switched [Step S1].
2], the sensor value (digital conversion value) can be acquired by switching the measurement range [step S13].

Particularly in this case, since it is not necessary to change the amplification factor of the output amplifier 3 in determining the measurement range as in the conventional case, it is possible to immediately obtain the digital conversion value in the switching-set measurement range. it can. That is, the analog processing of variably setting the amplification factor of the output amplifier 3 is not necessary, and the amplification factor according to the measurement range is individually determined by the plurality of preset output amplifiers 13, 13b, 13n. Since it is only necessary to select a digital conversion value corresponding to a plurality of types of amplified outputs, the switching can be performed quickly.

Therefore, even in the case where the test piece suddenly reacts due to the load application, the output amplifiers 13, 13b, ...
Since 3n obtains the amplified output under the preset amplification factor, the reaction state of the test piece, that is, the change in the load and elongation applied to the test piece can be reliably grasped. In particular, it is possible to obtain a digital conversion value in the optimum measurement range without causing a problem such as a response delay until the operation becomes stable due to the change of the amplification factor of the output amplifier 3. Therefore, measurement data with sufficiently high measurement resolution can be acquired under an appropriate measurement range, which is a great practical advantage.

Further, according to the above configuration, the output amplifier 1
In the analog system composed of 3, 13b to 13n, there is no need for switch processing such as switching the amplification factor, so there is no problem of noise generation due to switch processing, and good S / N measurement is possible. Can also be played. Further, since the switch processing in the analog system is not necessary, the circuit itself can be easily designed, and the configuration can be simplified.

The present invention is not limited to the above embodiment. For example, the plurality of measurement ranges may be set according to the load and elongation measurement ranges in the material testing machine and the required measurement resolution, and the number of channels is not limited. Also, the upper limit value and the lower limit value for executing the channel switching may be determined according to the measurement specifications. In addition, the present invention can be variously modified and implemented without departing from the scope of the invention.

[0020]

As described above, according to the present invention, a plurality of output amplifiers whose amplification factors are set in advance according to a plurality of measurement ranges are provided, and a multi-channel type A / D converter is used. Since the digital conversion value is obtained selectively according to the digital conversion value, even if the sensor output changes suddenly, the measurement range can be quickly switched and the measurement data can be leaked. S / N for measurements that can be acquired and have a simple configuration and high resolution
Practical great effects such as good execution can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a measurement system in a material testing machine according to an embodiment of the present invention.

FIG. 2 is a diagram for explaining the relationship between the sensor output and the amplified outputs (digital conversion values) of a plurality of output amplifiers in the measurement system shown in FIG. 1, and the switching mode of the amplified outputs.

3 is a diagram showing the flow of measurement range switching and sensor value acquisition in the measurement system shown in FIG.

FIG. 4 is a diagram showing a configuration example of a measurement system in a conventional general material testing machine.

FIG. 5 is a diagram showing a flow of switching a measurement range and acquiring a sensor value in a conventional measurement system.

[Explanation of symbols]

11 sensor 12 preamplifier (sensor amplifier) 13a, 13b, to 13n output amplifier (amplification factor according to measurement range) 14 A / D converter 15 controller 15a upper limit value judgment function 15b lower limit value judgment function 15c output control function

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) G01N 3/00-3/62 JISST file (JOIS)

Claims (2)

(57) [Claims] 1. A material testing machine for measuring a load applied to a test piece and an elongation generated in the test piece, wherein a sensor for measuring a load or an elongation applied to the test piece is different from a preset sensor. Maximum measurement value in the measurement range
Is the full scale of the digital conversion value that should be acquired
As described above, a plurality of output amplifiers for amplifying the output of the sensor with a fixed amplification factor respectively, and digital conversion values corresponding to the respective amplified outputs of these output amplifiers are obtained and the digital conversion values are selected. A multi-channel type A / D converter that is selected and output once and a digital conversion value that is output from this A / D converter are set in advance.
The A / D conversion is performed by comparing with the set upper and lower limits.
From the A / D converter to control the channel switching of the converter
When the output digital conversion value exceeds the upper limit above
Is the channel of the output amplifier whose amplification factor is set one step lower
And output from the A / D converter.
When the digital conversion value falls below the lower limit value, the amplification
Switch to the channel of the output amplifier with the rate set one step higher
Controller and the digital conversion value output from the A / D converter are currently
Within the specified measurement scale of the selected channel
When the digital conversion value output from the A / D converter is calculated,
A material testing machine, comprising: a data acquisition means for acquiring measurement data . 2. The predetermined value when acquiring the measurement data
The maximum measurement value of each measurement range corresponds to the measurement scale of
50 against the full scale of the A / D converter
What is set as a range from about% to about 95%
Material testing machine according to claim 1 is.