JP2518017B2 - Material testing machine - Google Patents

Description

The present invention relates to a material testing machine equipped with an automatic range switching device.

B. Conventional technology Apply load such as compressive force or tensile force to the test piece, measure the load and elongation at that time, record and display the load-elongation curve, or store the load and elongation data in the memory once. A material testing machine is known in which data processing is performed after the test to obtain various strength characteristic data on the test piece. Generally, in this type of material testing machine, in order to improve the resolution of the output from the load cell, the load amplifier connected to the load cell has a multi-stage load measurement range (hereinafter, simply referred to as “range”) Reduces the full scale and increases the full scale under high load. That is, the load value with respect to the maximum output voltage value of the load amplifier is increased / decreased by range switching to improve the resolution.

During the test, the maximum load is predicted and the optimum range (full scale) is selected.However, if the detected load exceeds the expected maximum load during the test, the load cannot be detected. When it reaches about 95%, the range is switched and the full scale is increased to continue the test.

Fig. 5 shows the load-elongation curve of such a material test. The elongation is 1t at full scale when the detected load is 95% of full scale, for example, full scale is 2t when S1 is exceeded. It is switching.

C. Problems to be solved by the invention For this reason, the resolution of load data in the region where the elongation exceeds S1 is half that of S1.

By the way, in FIG. 5, a shows the maximum yield point and b shows the minimum yield point, and the load value at each of these points is called a characteristic value, which is a very important factor for the strength evaluation of the test piece. However, as shown in FIG. 5, the resolution of these characteristic values is halved compared to the extension S1, and the accuracy of the data may be insufficient. In particular, as shown in Fig. 4, the maximum yield point a
Is below full scale, and if the load value just before that is 95% of full scale, that is, if the characteristic value is between 95% and 100% of full scale, change the range. If the test is continued without performing the test and the range is switched after the detected load exceeds the minimum yield point b, these characteristic values can be accurately obtained.

An object of the present invention is to provide a material testing machine equipped with an automatic range switching device capable of accurately measuring various characteristic values as described above.

D. Means for Solving Problems Explaining with reference to FIG. 1 which is a claim correspondence diagram, the material testing machine according to the present invention applies a load such as a compressive force or a tensile force to a test piece, and the test piece at that time In a material testing machine for measuring and displaying a physical quantity working on a physical quantity detecting means 10 for detecting the physical quantity working on the test piece and outputting a corresponding physical quantity signal.
1, a range setting means 102 for setting the range of physical quantity measurement by this physical quantity signal, a change detection means 103 for detecting a change due to the physical quantity, and various kinds of characteristic values based on the detected physical quantity and change. A signal processing means 105 for sending data to the output means 104, a judgment means 106 for outputting a judgment signal when it is judged that the characteristic value has been obtained by the signal processing means 105, and the physical quantity signal is determined by the range. By providing a control means 107 for switching the range by the range setting means 102 so that the full scale becomes large on condition that the predetermined ratio of the scale is reached and the determination signal is output, Solve the problem of.

E. Action When a load such as compressive force or tensile force is applied to the test piece, the physical quantity that acts on the detected test piece at that time, for example, the characteristic value is detected when the load reaches a predetermined percentage of full scale, for example 95% Then, the physical quantity (load) measurement range is switched so that the full scale becomes larger. Therefore, the resolution of the physical quantity (load) data near the characteristic value becomes high,
Highly accurate test results can be obtained.

F. Embodiment One embodiment of the present invention will be described with reference to FIGS.

FIG. 2 is a block diagram showing the overall configuration of the automatic range switching device. Here, a material testing machine in which this device is used, for example, holds a test piece through a pair of upper and lower gripping tools between a rising and falling crosshead and a fixed table, and loads the test piece by lifting and lowering the crosshead. Is.

The load meter 1 is installed on the crosshead and detects the load (physical quantity) acting on the test piece (measurement object) via the gripping tool and outputs a corresponding load signal. The extensometer 2 detects the elongation (change in the measured object due to the physical quantity) between the reference points of the test piece and outputs a corresponding elongation signal. The load amplifier 3 amplifies the load signal from the load meter 1, and the range selector switch 3a
By switching the switch driving circuit 3b, the resistors R1 to R3 can be switched to select the full scale (the load value indicated by the maximum output voltage of the load amplifier). The switch driving circuit 3b is driven by a range switching command from the manual operation unit 4 or a range switching command from the control circuit 9 described later to switch the switch 3a. Load amplifier
3. The analog signals of the manual operation unit 4 and the stroke amplifier 5 are converted into digital signals by the A / D converters 6 to 8 and sent to the control circuit 9.

The control circuit 9 is configured by connecting the input / output interfaces 9a and 9b, the central processing unit CPU, the random access memory RAM, and the read only memory ROM by the buses 9d and 9e.
The program of the processing procedure described later is stored in the ROM.
A data processing unit 10 is connected to the control circuit 9, and the data processing unit 10 calculates the maximum yield load, the minimum yield load, or the minimum yield load based on the load data LD obtained by digitizing the load signal and the elongation data SD obtained by digitizing the elongation signal. Various characteristic values such as proof stress are obtained, and various data processing is performed. A printer 12 is connected to the control circuit 9 via a D / A converter 11. This printer 12 draws a load-elongation curve as shown in FIG. 4 from the load data LD and the elongation data SD, or uses the maximum yield load, minimum yield load, proof stress, etc. determined by the data processing unit 10 as numerical values. Record and output. Further, the switch drive circuit 3b is connected to the control circuit 9 via the D / A converter 13, and the switch is provided on condition that the load data has reached 95% of full scale and the maximum yield point b has been detected. A range switching command is sent to the drive circuit 3b to increase the full scale. Next, the range switching operation will be described with reference to the flowchart shown in FIG. In the following, the full scale is set to the 1t range at the start of the test, and the full scale is set by switching the range.
The description will be made assuming that the setting is switched to 2t.

This procedure is executed when the material testing machine is started,
In step S1, the load data LD and the elongation data SD are sampled, and in the next step S2, these data are sent to the data processing unit 10 and predetermined data processing is performed to detect the maximum yield point a, the minimum yield point b, etc. Then, various characteristic values are obtained. In step S3, it is determined whether or not the load data LD exceeds the full scale, and if it exceeds, the material testing machine is stopped in step S9 and the process proceeds to the end. If not, the process proceeds to step S4, it is determined whether or not the test piece is broken, and if it is broken, the material testing machine is stopped in step S9.

If it is not broken, the test is continued and it is determined in step S5 whether the data processing unit 10 has detected the minimum yield point b. If the result is affirmative, it is determined in step S6 whether the load data LD has reached a value of 95% of full scale. If the result is affirmative, range switching is performed in step S7. In other words, change the full scale from 1t to 2t. After that, the process proceeds to step S8 and data processing associated with range switching is performed. That is, since the load signal output from the load amplifier 3 is disturbed when the range is switched, for example, the 10 sampled load data LD sampled after the range is switched are not stored, and the load data LD immediately before the range switch is stored. The data is replaced with the data of. After this processing,
Returning to step S1, the above means is repeated. Also, when the determinations in steps S5 and S6 are negative, the process returns to step S1.

According to such a procedure, for example, as shown in FIG. 4, the load data LD reaches 95% of the full scale a little before the maximum yield point, and the point where the load data LD is a little past the minimum yield point b is the full scale. In the test condition such that the load data LD reaches 95% of the full scale as in the conventional case, the range is not switched and the range is switched to the full scale 1t → 2t after the minimum yield point b is detected. Therefore, various characteristic values such as maximum yield load and minimum yield load can be measured with high resolution. When it is determined that the load data LD is 95% or more of the full scale after the minimum yield point b is detected, the range is switched, and therefore, after the extension S1 after the range is switched, the load is as shown in the figure. Recorded and displayed in 1/2 scale before range switching.

In the configuration of the above embodiment, the load meter 1 is the physical quantity detecting means 101, the range change switch 3a of the load amplifier 3 is the range setting means 102, and the extensometer 2 is the change detecting means 1.
03, the printer 12 constitutes the output means 104, the control circuit 9 constitutes the signal processing means 105, the control circuit 9 constitutes the determination means 106, and the control circuit 9 and the switch drive circuit 3b constitute the control means 107.

G. Effect of the Invention According to the present invention, for example, the maximum yield load, the minimum yield load, or the proof stress is a detection value that is important for measurement, such as switching the load measurement range after waiting for the detection of a characteristic value that is particularly important in material testing Since the physical quantity measurement range is switched after obtaining, the data of the characteristic value can be detected with high resolution, and the measurement accuracy is improved.

[Brief description of drawings]

FIG. 1 is a diagram corresponding to claims. 2 to 4 illustrate one embodiment of the present invention.
FIG. 2 is a block diagram showing the overall configuration, FIG. 3 is a flowchart showing an example of the processing procedure, and FIG. 4 is a graph of load-elongation curve. FIG. 5 is a graph of a load-elongation curve for explaining a conventional example. 1: Load meter, 2: Extensometer 3: Load amplifier 3a: Range switch 3b: Switch drive circuit 9: Control circuit 10: Data processing unit, 12: Printer

Claims (1)

(57) [Claims] 1. A material testing machine for applying a load such as a compressive force or a tensile force to a test piece and measuring and displaying the physical quantity working on the test piece at that time, detecting the physical quantity working on the test piece and detecting a corresponding physical quantity signal. A physical quantity detecting means for outputting, a range setting means for setting a range of physical quantity measurement by the physical quantity signal, a change detecting means for detecting a change due to the physical quantity, and a yield point or the like based on the detected physical quantity and change. The signal processing means for obtaining the characteristic value and sending various data to the output means, the determination means for outputting the determination signal for determining that the characteristic value is obtained by the signal processing means, and the physical quantity signal for the range The full scale is increased so that the full scale becomes large on the condition that a predetermined ratio of the full scale determined by is reached and the judgment signal is output. And control means for switching the range provided by the di-setting means, materials testing machine, characterized in that the maximum yield load, the characteristic values such as the minimum yield load or strength can be detected with high resolution.