JPH11230875A - Micro spring constant measuring device and spring constant measuring method - Google Patents

Abstract

(57) [Summary] To accurately measure a spring constant of a minute spring-like sample. A load is applied to an indenter having a flat tip by a load in a direction of an arrow. The displacement of the indenter at this time is measured by the displacement measuring unit 2. On the other hand, the leaf spring-shaped specimen 5 attached to the specimen holder 4 is brought directly below the indenter by a specimen stage (not shown). When the indenter 3 moves downward, the indenter 3
The flat tip pushes the sample 5 to deform the sample.
At this time, the indenter 3 is not pushed into the surface of the sample 5. The amount of deformation of the sample 5 is determined by the indenter 3 measured by the displacement measuring unit 2.
Is considered the same as the displacement of the indenter 3
The spring constant of the sample 5 is determined from the relationship with the load applied to the sample.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a minute spring constant measuring apparatus which can measure the spring constant of minute springs having various shapes such as very thin and small leaf springs and minute coil springs, and a spring constant measuring apparatus using the same. Related to the measurement method. In particular, the present invention relates to a minute spring constant measuring apparatus suitable for measuring a spring constant of a minute spring-like member such as a cantilever or a double-sided lever used in an atomic force microscope or the like, and a method of measuring the spring constant.

[0002]

2. Description of the Related Art In order to measure the spring constant of a spring made of a steel plate having a thickness of about several tens of μm, it is necessary to apply a load of mN unit to a sample and accurately detect a displacement of μm unit. . Conventionally, a load having the above-mentioned magnitude can be generated and measured by a balance mechanism, while displacement can be measured by a displacement meter using a differential transformer or the like.

[0003]

In order to measure the spring constant, it was possible to generate and measure a very small load and measure a very small displacement, respectively. There was no method to measure and no device to realize it.

In particular, it has been extremely difficult to measure the spring constant of a minute member such as a minute cantilever or a double-ended lever used as a probe of an atomic force microscope.

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and provides a minute spring constant measuring apparatus capable of measuring the spring constant of a minute spring with a simple mechanism, and a method of measuring the spring constant using the same. The purpose is to provide.

[0006]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention obtains an indenter having a flat tip, a load applying unit for applying a load to the indenter, and a moving amount of the indenter. A displacement measuring unit for determining a spring constant of the sample based on a load applied to the indenter and a displacement of the indenter when the indenter is brought into contact with the sample;

Further, in a measuring method for applying a predetermined load to the sample and obtaining the spring constant of the sample from the deformation amount of the sample at that time, a load applying portion for applying a load to an indenter in contact with the sample and a moving amount of the indenter are determined. A displacement measuring unit to be obtained is provided, the tip of the indenter is formed in a plane, a load generated in the load applying unit is applied to the sample by the indenter, and the deformation amount of the sample at that time is measured by the displacement measuring unit. The spring constant of the sample is obtained based on the following equation.

[0008] The minute spring constant measuring apparatus of the present invention is provided with a load applying section capable of applying a minute load and a displacement measuring section capable of measuring a minute displacement. Using this small spring constant measurement device, when a spring-shaped sample is pressed using a flat tip indenter instead of a sharp tip indenter used in a microhardness tester, the load and the indenter The displacement amount, that is, the deformation amount of the spring-like sample can be measured simultaneously. The spring constant of the sample can be calculated from the load applied at this time and the amount of deformation of the sample.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a main part of a minute spring constant measuring device of the present invention. When the load unit 1 applies a load to the indenter 3 pressed against the sample 5, the indenter 3 is displaced in the direction of arrow P. The displacement amount at this time is measured by the displacement measuring unit 2. The load unit 1 includes a well-known roberval mechanism and a force generation unit including a magnet and an electromagnetic coil, and the displacement measurement unit 2 includes a differential transformer. Sample 5 in FIG. 1 is an example using a double-sided lever as a sample.

The indenter 3 has a conical or pyramid-shaped tip, and the tip of the indenter 3 has a relatively large flat surface 3a, unlike an indenter having a sharp pointed tip such as a normal microhardness tester. Is formed. This is to prevent the indenter 3 from biting into the sample 5 when pressed against the surface of the sample 5. That is, since the planar shape of the tip of the indenter 3 is to prevent biting into the sample, the planar shape is not limited to an absolute plane but includes a shape that can be regarded as a substantially flat surface such as a spherical shape having a large radius of curvature.

The measurement is performed as follows. First, the leaf spring-shaped specimen 5 attached to the specimen holder 4 is brought directly below the indenter 3 by a specimen stage (not shown). When the indenter 3 is moved in the direction of arrow P by the force applied by the load unit 1, a load starts to be applied when the tip of the indenter 3 comes into contact with the surface of the sample 5. Is determined as the point of contact. Further, the load is applied to the indenter 3 while the load is measured by the load unit 1 at a constant load speed, and the displacement of the indenter 3 is measured by the displacement measuring unit 2. At this time, the measured value obtained by the displacement measuring unit 2 is the displacement amount of the indenter 3,
Since the indenter 3 is simply pushed and deformed without being pushed into the surface of the sample 5, it can be regarded as the deformation amount of the sample 5.

When the obtained data is plotted as a load on the vertical axis and a displacement on the horizontal axis, a graph as shown in FIG. 2 is obtained. A point T in FIG. 2 represents a point in time when the indenter and the sample come into contact with each other. Data at a position where the displacement is larger than the point T is represented as a substantially linear L. When the L portion is approximated to a linear line by the least square method or the like, the spring constant of the sample 5 can be obtained from the slope.

FIG. 3 shows a measurement example in which the spring constant of the double-sided lever as illustrated in FIG. 1 is measured. FIG. 3A shows the measured values, and FIG. 3B shows the measured values graphically. The same sample was measured twice (measurement 1 and measurement 2), and a straight line L1 and a straight line L2 in FIG. 3B were obtained.
From each straight line, the value of the spring constant is 305.6 (N / m) and 305.
It was calculated as 1 (N / m) and the average was calculated as 305.4 (N / m). Note that the point at which the indenter contacts the sample is shifted in the two measurements simply because the set initial position of the sample is shifted, and does not affect the measurement of the spring constant.

[0014]

According to the minute spring constant measuring apparatus and the spring constant measuring method of the present invention, an indenter having a flat tip, a load mechanism for applying a small force to the indenter, and a minute displacement of the indenter can be measured. Using the displacement measuring mechanism, a minute force is applied to the sample, and the resulting minute displacement is measured, so that the spring constant of a very small spring-like member can be accurately measured.

[Brief description of the drawings]

FIG. 1 is a diagram showing a main part of a minute spring constant measuring device of the present invention.

FIG. 2 is a diagram illustrating a relationship between a load applied to a sample and an amount of deformation of the sample.

FIG. 3 is a measurement example of a spring constant of a double-sided lever.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Load part 2 ... Displacement measuring part 3 ... Indenter 4 ... Sample holder 5 ... Sample

Claims (2)

[Claims] 1. An indenter having a flat tip, a load applying unit for applying a load to the indenter, and a displacement measuring unit for determining an amount of movement of the indenter, wherein the indenter is brought into contact with a sample. A spring constant of the sample is obtained based on a load applied to the indenter and a displacement of the indenter. 2. A method for applying a predetermined load to a sample, and determining a spring constant of the sample from a deformation amount of the sample at that time, wherein a load applying portion for applying a load to an indenter in contact with the sample and a moving amount of the indenter are determined. A displacement measuring unit to be obtained is provided, the tip of the indenter is formed in a plane, a load generated in the load applying unit is applied to the sample by the indenter, and the deformation amount of the sample at that time is measured by the displacement measuring unit. A method of measuring a spring constant, wherein a spring constant of a sample is obtained based on the following.