JP2001296225A - Material tester - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a material tester, capable of obtaining a true load on a real-time basis without correcting the measured value after a test. SOLUTION: A load F applied to a sample 4 is inputted to a CPU 20 by a load set section 21, and a current is fed to a solenoid coil 8a from a current feed section 14 via a D/A converter 17. An indenter 5 is lowered via a fulcrum 7 by the repulsion against a magnet 8b. When the indenter 5 is kept with contact with the sample 4, α=I/d is obtained from the linear correlation between the current I and a displacement d of the indenter 5. When the indenter 5 is brought into contact with the sample 4 during the test, the displacement d is measured by a displacement measurement section 16, and F=k(I-αd) is calculated by the CPU on a real-time basis. When this value reaches the set load F, the test is finished, and the true force and the displacement d are displayed on a display section 22.

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, and more particularly to a microhardness tester and a compression / tensile testing machine for measuring the hardness of a sample from an indentation by pressing an indenter against the test material.

[0002]

2. Description of the Related Art In order to evaluate the hardness of a material, there is a microhardness tester in which an indenter applied with a predetermined load is pressed into a sample and the hardness of the sample is measured from the indentation. In a Vickers hardness tester or the like, a load device using a permanent magnet and an electromagnetic coil is used to press an indenter having a tip formed into a predetermined shape into a sample. FIG. 3 shows a conventional microhardness tester. A sample table 2 that can be moved up and down in a frame 1
Has a stage 3 movable in XY directions orthogonal to each other.
Are provided detachably, and the sample 4 is placed and fixed on the stage 3.

As shown in detail in FIG. 4, a self-balancing electronic balance type load device 9 provided in a frame 1 has an electromagnetic force generating device 8 comprising a magnet 8b and an electromagnetic coil 8a. The force generator 8 generates a force according to the current supplied from the control unit 13a to the electromagnetic coil 8a. One end of a lever 24 that can swing around the fulcrum 7 is located below the electromagnetic force generator 8 and is connected to the electromagnetic coil 8a.
Rotates about the fulcrum 7. The amount of rotation of the lever 24 is increased by increasing the supply current to the electromagnetic coil 8a, and when the supply current is maintained at a constant value, the lever 24 is held in the rotation posture at that time.

The other end of the lever 24 is connected to an indenter holding member 27 via a leaf spring 25 and a bracket 26, and an indenter 5 for suppressing the sample 4 on the stage 3 is attached to the lower end of the holding member 27 in the figure. Have been. Link 29
Has one end at the upper and lower portions of the holding member 27 and the other end
A pair of links each rotatably connected to the
These links 29 constitute a parallel link mechanism. As the lever 24 rotates, the holding member 27, that is, the indenter 5, moves up and down while maintaining the same posture by the action of the parallel link mechanism.

[0005] Reference numeral 6 in FIG. 3 denotes a differential transformer type displacement detector for detecting the amount of displacement of the indenter 5, and the detection result is input to a displacement measuring unit 16 of the control unit 13a. Control unit 13a
Is a displacement measuring unit 16 based on an input signal from the displacement detector 6.
, A predetermined load level is set by the load setting unit 21, power is supplied from the current supply unit 14 to the electromagnetic coil 8 a, and the indenter 5 is obtained from the current I measured by the current measurement unit 15. A predetermined calculation process is performed based on the pressing load F = kI (k: conversion coefficient between current and force) on the sample 4 of
The apparent force F, the displacement d, and the hardness are displayed on the display unit 22 as the hardness data of the sample 4. Reference numeral 10 denotes an optical monitor as an auxiliary device, which includes an objective lens 11 and an eyepiece 12, and measures the test position on the surface of the sample 4 and checks the state of the dent formed on the sample surface by the indenter 5. Used for observation by workers.

[0006]

The conventional material testing machine is constructed as described above, but the current I flowing through the electromagnetic coil 8a of the electromagnetic force generator 8 is measured by the current measuring unit 15,
When calculating the pressing load F of the indenter 5 from the value of the current I,
The pressing load F = kI was calculated simply by multiplying the conversion coefficient k between the current I and the apparent force F. Or,
After the test, the correlation between the displacement d until contact with the sample 4 and the current I was obtained, and the pressing load F was corrected based on this value to obtain a true pressing load F ′.

As described above, by simply multiplying the conversion coefficient k between the current I and the apparent force F, the pressing load F = kI
In the method of calculating, a value including an error is obtained because the current value I when the indenter 5 is not loaded is not corrected. In the method of calculating and correcting after the test, a measured value can be obtained in real time. There is a problem that can not be done. For this reason, there is a problem that the set force cannot be applied.

The present invention has been made in view of such circumstances, and is not a method of correcting a measured value after a test, but a material testing machine capable of obtaining a real pressing load F in real time. The purpose is to provide.

[0009]

In order to achieve the above object, a material tester according to the present invention applies a predetermined load to a sample by means of an electromagnetic force generating means, measures a deformation amount of the sample, and measures the hardness or compression of the sample. In a material testing machine for measuring tensile strength, a current is applied to an electromagnetic force generating means, and a function of measuring displacement and current of the indenter until the driven indenter comes into contact with the sample has a function of measuring the indenter's absence. The data of the correlation between the displacement under load and the current is taken into the CPU, and the displacement amount and current value of the indenter when a predetermined load is applied to the sample are measured by the displacement measurement unit and the current measurement unit. The correction value is calculated from the data of the correlation between the displacement at the time and the current, corrected in real time, the true pressing load is calculated, and when the true pressing load reaches the set value, the test is terminated, and the calculated true Display the load value and displacement on the display Is shall.

[0010] The material testing machine of the present invention is configured as described above. The current is applied to the electromagnetic force generating means, and the displacement and current of the indenter until the driven indenter comes into contact with the sample are measured for displacement. The CPU calculates a correction value from the data of the correlation between the displacement and the current at the time of non-contact, and subtracts the force at the time of non-contact from the apparent force during the test. Correction is performed by the CPU in real time,
The test can be terminated when the true force is applied to the sample. Further, the calculated true load value and displacement amount can be displayed on the display unit.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the material testing machine of the present invention will be described with reference to FIG. FIG. 1 is a diagram showing a measurement system of a material testing machine according to the present invention. This material testing machine includes a testing machine main body, a control unit 13 thereof, and a display unit 22. The testing machine body is the same as the conventional micro hardness tester,
A stage 3 is provided, on which a sample 4 is mounted and fixed, and on which the sample 4 can be moved up and down, a load device 9 of an automatic balance type electronic balance type provided in the frame 1, and a displacement of the indenter 5 is detected. It comprises a displacement detector 6 and an optical monitor 10 as an auxiliary device.

The sample stage 2 is provided with a stage 3 which is movable in XY directions orthogonal to each other, and is detachably provided.
The sample 4 is mounted and fixed thereon, and has a mechanism capable of moving up and down. As shown in FIG. 4, the load device 9 includes a magnet 8b.
And an electromagnetic force generating device 8 including an electromagnetic coil 8a. The device 8 generates a force according to the current supplied from the control unit 13 to the electromagnetic coil 8a. Electromagnetic force generator 8
One end of a lever 24 that can swing around the fulcrum 7 is located below and is connected to the electromagnetic coil 8a, and the lever 24 rotates around the fulcrum 7 by the force generated by the electromagnetic force generator 8. . The amount of rotation of the lever 24 increases by increasing the supply current to the electromagnetic coil 8a, and when the supply current is maintained at a constant value, the lever 24 is held in the rotation posture at that time.

The other end of the lever 24 is connected to an indenter holding member 27 via a leaf spring 25 and a bracket 26. An indenter 5 for suppressing the sample 4 on the stage 3 is attached to the lower end of the holding member 27 in the figure. Have been. Link 29
Has one end at the upper and lower portions of the holding member 27 and the other end
A pair of links each rotatably connected to the
These links 29 constitute a parallel link mechanism. As the lever 24 rotates, the holding member 27, that is, the indenter 5, moves up and down while maintaining the same posture by the action of the parallel link mechanism.

The displacement detector 6 is of a differential transformer type that detects the amount of displacement of the indenter 5, and the detection result is input to a displacement measuring unit 16 of the control unit 13. Optical monitor 10
Is used as an auxiliary device and includes an objective lens 11 and an eyepiece lens 12, etc., and measures a test position on the surface of the sample 4 and an operator observes a state of a depression formed on the sample surface by the indenter 5. Used for

The control unit 13 controls the electromagnetic coil 8 of the load device 9.
a current supply unit 14 for supplying a current to a, a current measurement unit 15 for measuring a current flowing through the electromagnetic coil 8a,
A displacement measuring unit 16 for detecting and measuring a displacement amount of the indenter 5 of the load device 9 driven by the current by the displacement detecting unit 6;
A load setting unit 21 for setting a load value, a CPU 20 of a data processing device for calculating a correction value from a control of each unit and the acquired data and calculating a true pressing load F, and a D / A as an interface between the CPU 20 and each unit. Converter 17 and A
/ D converters 18 and 19. The load setting unit 21 sets the pressing load F of the sample 4, the set value is converted into an analog value by the D / A converter 17 via the CPU 20, and the current is supplied from the current supply unit 14 to the electromagnetic coil 8a. Supplied.

The current measuring unit 15 measures a current flowing through the electromagnetic coil 8a, and a current value linearly related to a displacement until the indenter 5 comes into contact with the sample 4, and a set pressing load upon contact. And the current value at which the
The data is converted into a digital value by the / D converter 18 and processed by the CPU. The displacement measuring section 16 detects the amount of displacement of the indenter 5 with the displacement detector 6, and the value of the displacement is measured by the A / D converter 19.
Is converted into a digital value, and is processed by the CPU. The display unit 22 displays the true pressing load F calculated by the CPU 20 of the control unit 13, the displacement d of the sample 4 by the indenter 5, the resulting hardness, other information of the sample, and the like.

Next, the operation of the material testing machine and the CPU 2
The data processing of 0 will be described. First, a pressing load value is input to the CPU 20 by the load setting unit 21. According to the value, a current is supplied from the current supply unit 14 to the electromagnetic coil 8a, and a force is applied to the indenter 5 by the fulcrum 7 by a repulsive force with the magnet 8b. Until the indenter 5 contacts the sample 4, as shown in FIG. 2, the current I and the displacement d of the indenter 5 have a linear correlation. This current I and α of displacement d =
The CPU 20 calculates I / d. This α value is stored in the storage device. This operation may be performed before the test.

As a method of detecting the contact of the indenter 5 with the sample, α = I / d until the indenter 5 contacts the sample.
Is constant and does not change, but the value of α increases upon contact. The point in time is the time of contact. Then, during the test, the indenter 5 comes into contact with the sample 4, and a current is applied until a predetermined pressing load value is reached. When the indenter 5 is pressed against the sample 4, the displacement d of the indenter 5 and the current I are determined. Are measured by the displacement measuring unit 16 and the current measuring unit 15. At that time, the CPU 20 calculates the arithmetic expression F
= K (I-αd). Here, k is a conversion coefficient between the current I and the force F. When the F value reaches the pressing load value set by the load setting unit 21, the test is terminated.

The first term kI of the equation F = k (I-αd)
Represents the apparent force, the second term kαd is the force when the indenter 5 does not contact the sample 4, and the force of the second term kαd is not the force applied to the sample 4. Therefore, in order to correct this component, it is necessary to correct the first term by subtracting the second term. CPU 20 performs this calculation in real time.

In the above-described embodiment, digital control is performed using the CPU 20, but data processing F = k (E) is performed by an analog-controlled electric circuit without using the D / A converter 17, the A / D converters 18 and 19. The operation of I-αd) can also be performed. Further, in the above embodiment, the microhardness tester was described, but the present invention can be similarly applied to a compression / tensile tester for applying a compressive load or a tensile load to a test material.

[0021]

The material testing machine of the present invention is constructed as described above, and uses the correlation between the current and the displacement when the indenter is not in contact before the test to obtain an apparent value during the test. Correction by subtracting the force at the time of non-contact from the force is performed by the CPU in real time, and the test can be terminated when the true force is applied to the sample. As a result, the test is completed when the set pressure is reached by using the corrected force without the need for the post-test data correction as in the past, and the hardness tester with this function, compression / tensile test Inexpensive and precise measurement can be performed on the machine.

[Brief description of the drawings]

FIG. 1 is a view showing one embodiment of a material testing machine of the present invention.

FIG. 2 is a diagram showing a relationship between a displacement until an indenter contacts a sample and a driving current.

FIG. 3 is a view showing a conventional material testing machine.

FIG. 4 is a diagram illustrating a mechanism of a driving unit of the material testing machine.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Frame 2 ... Sample stage 3 ... Stage 4 ... Sample 5 ... Indenter 6 ... Displacement detector 7 ... Support point 8 ... Electromagnetic force generator 8a ... Electromagnetic coil 8b ... Magnet 9 ... Load device 10 ... Optical monitor 11 ... Objective lens DESCRIPTION OF SYMBOLS 12 ... Eyepiece 13 ... Control part 14 ... Current supply part 15 ... Current measurement part 16 ... Displacement measurement part 17 ... D / A converter 18 ... A / D converter 19 ... A / D converter 20 ... CPU 21 ... Load Setting part 22 ... Display part 23 ... Pressing load calculating part 24 ... Lever 25 ... Leaf spring 26 ... Bracket 27 ... Holding member 28 ... Fixing part 29 ... Link

Claims (1)

[Claims] A material tester for applying a predetermined load to a sample by means of an electromagnetic force generating means and measuring the deformation of the sample to measure the hardness and compression / tensile strength of the sample. A supply unit, a displacement measuring unit that measures displacement of the indenter until the driven indenter contacts the sample, and when a predetermined load is applied to the sample, a current measuring unit that measures current, and the measurement thereof And a control unit for processing the obtained data.The control unit calculates a correction value from the data of the correlation between the displacement of the indenter when no load is applied and the current, corrects the data in real time, calculates the true pressing load, and A material testing machine characterized in that the test is terminated when the pressing load of the sample reaches a set value, and the calculated true load value and displacement are displayed on a display unit.