JP4164682B2 - Material testing machine - Google Patents

Description

  The present invention relates to a material testing machine having a load mechanism for applying a load to a test piece, a test force acting on the test piece, and a function of measuring distortion of the test piece.

  In a material testing machine, in general, a load such as tension or compression is applied to a test piece, and the test force acting on the test piece or the strain such as elongation of the test piece is measured every moment, and the test force or strain is measured. Investigate the material properties of the test piece from the measurement results.

  The test force acting on the specimen is detected by a load cell, and the elongation of the specimen is detected by a strain gauge. These detection outputs are usually free from noise by passing through a filter suitable for each output (see, for example, Patent Document 1).

FIG. 2 is a block diagram showing a configuration example of a main part of a conventional material testing machine.
In this example, after the output of the load cell 22 attached to the tester main body 21 and the output of the extensometer 23 attached to the test piece W are amplified by the load amplifier 22a and the strain amplifier 23a, respectively, Filtering is performed by the corresponding analog filters 22 b and 23 b, digitized by the A / D converters 22 c and 23 c, and taken into the testing machine controller 24. In the tester controller 24, among the measurement data of the test force and strain, the data set in the control amount matches the preset target value so that the actuator 25 of the load mechanism of the tester main body 21 is the same. To control. The test force and strain measurement data is taken into the data processing / storage personal computer 26 through the tester controller 24, processed into a load-elongation curve, and stored.

In addition to using the analog filter as described above, after each detection output is digitized, digital data filtering, so-called digital filter processing may be performed by software.
Japanese Patent Laid-Open No. 64-86035

  By the way, in the conventional material testing machine as described above, the filter characteristics of the test force and strain detection output are basically fixed when an analog filter is used. For example, the cutoff frequency and the filter ON -The user can change the setting for certain limited characteristics such as OFF. In addition, in the case of subjecting each detection signal to digital filter processing, since complex filter processing cannot be performed in real time, only simple filtering such as moving average can be originally performed.

  From the above, in the conventional material testing machine, the filter characteristics of each detection output by the test force and extensometer cannot be changed substantially, and the optimum filtering is not necessarily performed. There was a problem that it was difficult to say.

  The present invention has been made in view of such circumstances, depending on the type of load cell and extensometer used in the testing machine, the amount of noise superimposed on each detection output based on disturbance, etc. An object of the present invention is to provide a material testing machine capable of always performing an optimal filtering process on the detected output.

In order to solve the above problems, a material testing machine of the present invention includes at least a load mechanism for applying a load to a test piece, a test force acting on the test piece, and a load cell and a strain gauge for detecting the strain of the test piece, respectively. In the material testing machine, a filter for inputting the test force detection output by the load cell and the strain detection output by the strain gauge, and a storage means for storing a plurality of types of filtering methods and parameters respectively corresponding to the filters. A discrimination means for discriminating types of the load cell and the strain meter , a noise amount detection means for detecting a noise amount superimposed on each detection output of the load cell and the strain gauge , a discrimination result by the discrimination means and a noise amount detection means based on the detection result, the filtering of a plurality of types stored in the storage means From the methods and parameters, characterized by that it comprises a setting means for setting the method and parameters suitable for each filter automatically selected and (claim 1).

  Here, in the present invention, each filter is a digital signal processing means configured by programmable hardware, and the detection output of the test force by the load cell and the detection output of the distortion by the strain meter are converted to the above-mentioned respective values after digitization. In addition to being guided to the digital signal processing means, the setting means selects a suitable program from a plurality of programs of each digital signal processing means stored in the storage means, and loads the program of each digital signal processing means. It is preferable that the information is rewritten (Claim 2).

  The present invention is based on the type of load cell and strain gauge used, or the amount of noise superimposed on the signal, etc., and a plurality of filtering methods and parameters stored in advance are suitable for each detection output. By automatically selecting and setting each filter for each detection output, an intended purpose is achieved.

That is, for each of the filters from which the test force by the load cell and the strain detection output by the strain gauge are derived, a plurality of types of filtering methods and parameters are stored, and the type of the load cell or strain gauge is determined from these. results, and, in accordance with the detection result of the amount of noise superimposed on the detection outputs, select the methods and parameters suitable for filtering each detection output, automatically by setting each filter in question Optimal filter processing can always be performed according to the signal state.

  As a specific configuration for realizing such a filter, as in the invention according to claim 2, digital signal processing means configured by hardware capable of programming the filter, specifically, an FPGA (Field Progamable Gate). A so-called programmable logic device such as Alley) or CPLD (Complex Programmable Logic Device) is used, and a digital filter circuit is configured by hardware using such a device. In such a programmable logic, for example, the logic written in the dedicated ROM is configured, but the dedicated ROM is made rewritable and stored in different storage means. By selecting and transferring the most suitable logic in accordance with the state of each detection signal, it is possible to make the filter based on each programmable logic suitable for each detection output.

According to the present invention, the type of load cell or strain gauge is automatically determined, the amount of noise superimposed on each output from the load cell or strain gauge is automatically detected, and the determination result and detection are detected. Based on the results , the filtering method and parameters of the filter that filters the detection output of the load cell and strain gauge are automatically selected and set, so depending on the signal status caused by the material test setting status and environment, etc. It is possible to perform minimum filtering.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing the main configuration of an embodiment of the present invention.

  The testing machine main body 1 includes a load mechanism 1a, a cross head 1c that moves up and down with respect to the table 1b by driving the load mechanism 1a, and a pair of grips 1d that are respectively attached to the table 1b and the cross head 1c. 1e is mainly used, and the test piece W is used for the test in a state where both ends thereof are gripped by the gripping tools 1d and 1e.

  A load cell 2 is interposed between the upper gripping tool 1e and the crosshead 1c, and a test force acting on the test piece W is detected by the load cell 2. Further, an extensometer 3 is attached to the test piece W, and the elongation of the test piece W is detected by the extensometer 3.

  The outputs of the load cell 2 and the extensometer 3 are amplified by the load amplifier 2a and the strain amplifier 3a, respectively, digitized by the AD converters 2b and 3b, and then provided in correspondence to the FPGA 2c. And 3c.

  Dedicated EPROMs 2d and 3d and a CPU 4 are connected to the FPGAs 2c and 3c, respectively, and logics written in the corresponding EPROMs 2d and 3d are programmed in the FPGAs 2c and 3c, respectively. The contents of the EPROMs 2d and 3d are rewritten by the CPU 4 correspondingly. The CPU 4 selects the optimum logic among a plurality of types of logic written in the ROM 5 provided separately and updates the contents of the EPROMs 2d and 3d as will be described later. The plurality of types of logic written in the ROM 5 are all logics for the FPGAs 2c and 3c to filter the signals digitized by the A / D converters 2b and 3b. Different filtering parameters and filtering methods are realized. Accordingly, each of the FPGAs 2c and 3c becomes a filter circuit having substantially different filtering methods and parameters in accordance with the selection of logic in the ROM 5 by the CPU 4 to the contents written in the EPROMs 2d and 3d.

  The CPU 5 automatically recognizes the type of the load cell 2 and the type of the extensometer 3 attached to the testing machine main body 1 by a known method such as a short circuit state between predetermined pins of the connector, and further warms up prior to the test. In some cases, the level of disturbance noise or the like is recognized from the data passed through the FPGAs 2c and 3c, and a plurality of filtering methods and parameters stored in the ROM 5 are realized based on such information. Then, the optimum one is selected and written in the EPROMs 2d and 3d. As a result, the FPGAs 2c and 3c perform optimum filtering processing on the test force detection data and the elongation detection data input to the FPGAs 2c and 3c, respectively, and output them as test force data and elongation data.

  The test force data and the elongation data that have been subjected to the optimum filtering process are taken into the tester controller 6, and the tester controller 6 uses the data set as the control amount as the target value. In comparison, the load mechanism 1a of the testing machine main body 1 is driven and controlled. Further, the test force data and the elongation data after the filtering process are taken in and stored in the data processing personal computer 7 and processed into test information such as a load-elongation curve.

  In the above embodiment, an example in which an FPGA is used as the programmable logic has been described. However, it is a matter of course that an element having an equivalent function such as a CPLD or a DSP (Digital Signal Processor) can be used.

  In the above embodiment, an example in which an extensometer is attached to a test piece to measure the elongation has been described. However, a compressive load is applied to the test piece to measure its compressive strain, or a bending load. Needless to say, when measuring the bending distortion by applying the above, each of these distortion detection outputs can be configured to perform optimum filtering in the same manner as in the above-described example.

It is a block diagram which shows the principal part structure of embodiment of this invention. It is a block diagram which shows the principal part structure of the conventional material testing machine.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Test machine main body 1a Drive mechanism 1b Table 1c Cross head 1d, 1e Grasping tool 2 Load cell 3 Extensometer 2a Load amplifier 3a Strain amplifier 2b, 3b AD converter 2c, 3c FPGA
2d, 3d EPROM
4 CPU
5 ROM
6 Test machine controller 7 Personal computer W Test piece

Claims (2)

In a material testing machine comprising at least a load mechanism that applies a load to a test piece, a load cell that detects a test force acting on the test piece, and a strain of the test piece, and a strain gauge, respectively.
Filters for inputting test force detection output by the load cell and distortion detection output by a strain meter, storage means for storing a plurality of types of filtering methods and parameters respectively corresponding to these filters, and the load cell and distortion Based on the determination means for determining the type of meter, the noise amount detection means for detecting the amount of noise superimposed on each detection output of the load cell and strain gauge , the determination result by the determination means and the detection result by the noise amount detection means , A material testing machine comprising a setting means for automatically selecting and setting a method and parameters suitable for each filter from a plurality of types of filtering methods and parameters stored in the storage means. .   Each filter is a digital signal processing means configured by programmable hardware, and the test force detection output by the load cell and the distortion detection output by the strain gauge are guided to the digital signal processing means after digitization. The setting means rewrites a program of each digital signal processing means by selecting a suitable one from a plurality of programs of each digital signal processing means stored in the storage means. 2. The material testing machine according to 1.

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