JP4863354B2 - Indenter shaft and material testing machine - Google Patents

Description

  The present invention relates to an indenter shaft and a material testing machine.

  2. Description of the Related Art Conventionally, as a material testing machine, for example, a hardness testing machine that measures a physical property value such as the hardness of a material by pushing an indenter shaft into a sample surface to form a recess is known. Specifically, for example, the hardness tester measures the indentation depth when the tip of the indenter shaft is pushed into the sample surface, that is, the displacement amount of the indenter shaft with a displacement meter, and measures the measured displacement amount. The physical property value such as hardness of the sample is measured by obtaining the relationship between the load and the load when the indenter shaft is pushed into the sample surface.

By the way, the hardness tester is used, for example, when evaluating temperature dependency such as hardness of a sample. In this case, the hardness tester includes, for example, a sample stage heater that heats the sample stage, and the sample placed on the sample stage is heated by heating the sample stage by the sample stage heater. It has become.
In such a hardness tester, the indenter is brought into contact with a heated sample during measurement of the hardness of the sample or the like, or the heated sample table heats the air in the vicinity of the sample table. The shaft is also heated and thermally expanded. Further, the hardness tester constituent members (tester frame and the like) also thermally expand due to the influence of the high temperature atmosphere. Thus, when the indenter shaft and the hardness tester constituting member are thermally expanded, there is a problem that an accurate indentation depth of the indenter shaft cannot be measured.

Therefore, for example, in a hardness tester (indentation test apparatus) having an indenter shaft, a both-end supported beam having the indenter shaft attached to the center, and a support portion for the both-end supported beam that supports the both-end supported beam, A hardness tester (for example, a super invar) in which at least one of the both-end support beam and the support portion for both-end support beam, which is a component of the hardness tester, is formed of a material having a low coefficient of thermal expansion (specifically, Super Invar) , See Patent Document 1) and the like.
JP 2004-12178 A

  However, Patent Document 1 can cope with the thermal expansion of the hardness tester constituting member, but cannot cope with the thermal expansion of the indenter shaft.

  An object of the present invention is to provide an indenter shaft capable of reducing the influence of thermal expansion and a material testing machine having the indenter shaft.

In order to solve the above-mentioned problem, the invention described in claim 1 is directed to an indenter shaft (2) in which an indenter (21) is provided at the tip of the indenter shaft body (22). It is characterized by being formed of super invar having a smaller absolute value of thermal expansion coefficient than steel.

The invention according to claim 2 is the indenter shaft (2a) in which an indenter (21a) formed of a material having a positive thermal expansion coefficient is provided at a tip portion of the indenter shaft body (22a). The main body is composed of a first indenter shaft body (22a1) formed of a material having a negative thermal expansion coefficient and a second indenter shaft body (22a2) formed of a material having a positive thermal expansion coefficient, The sum of the length in the pushing direction of the indenter, the length in the pushing direction of the first indenter shaft body, and the length in the pushing direction of the second indenter shaft body is the pushing direction from the tip of the indenter to the displacement detection reference. It is set so that it may become the same as this length.

According to a third aspect of the present invention, in the indenter shaft according to the second aspect , the material having a negative coefficient of thermal expansion is hexagonal boron nitride.

According to a fourth aspect of the present invention, in the indenter shaft according to the second aspect , the material having a negative coefficient of thermal expansion is aluminum titanate.

According to a fifth aspect of the present invention, the indenter of the indenter shaft according to any one of the first to fourth aspects is pushed into the surface of the sample (S) to form a recess, and a predetermined material of the sample is formed based on the recess. It is characterized by evaluating characteristics.

The invention according to claim 6 is the material testing machine according to claim 5 , wherein the sample table (11) for placing the sample, the heating / cooling unit (13) for heating or cooling the sample table, Temperature detection means (for example, temperature detection section 12) for detecting the temperature in the vicinity of the sample placed on the sample stage, and the heating and cooling section based on the temperature detected by the temperature detection means to control the sample Control means (for example, control part 14) which controls the temperature of a stand.

According to the first aspect of the present invention, the indenter shaft body is formed of a material having a smaller absolute value of the thermal expansion coefficient than stainless steel conventionally used as the indenter shaft body. Thus, it becomes difficult for the indenter shaft to thermally expand (or shrink), and the influence of the thermal expansion of the indenter shaft can be reduced.
Further, the indenter shaft main body is not only small in thermal expansion coefficient but also formed of super invar excellent in workability, and therefore can be easily molded.

According to the second aspect of the present invention, since at least a part of the indenter shaft body is formed of a material having a negative thermal expansion coefficient, the thermal expansion of the indenter formed of a material having a positive thermal expansion coefficient is prevented. Since it can cancel, the influence of the thermal expansion of the indenter shaft can be reduced.

According to the invention described in claim 3 , it is needless to say that the same effect as that of the invention described in claim 2 can be obtained, and at least a part of the indenter shaft body has not only a negative coefficient of thermal expansion. Since it is formed of hexagonal boron nitride that is excellent in workability and non-oxidizing, it can be easily molded and has high durability.

According to the invention described in claim 4 , it is needless to say that the same effect as that of the invention described in claim 2 can be obtained, and at least a part of the indenter shaft body has not only a negative coefficient of thermal expansion. Since it is formed of aluminum titanate having excellent workability and high corrosion resistance, it can be easily molded and has high durability.

According to the invention described in claim 5 , since the indenter shaft according to any one of claims 1 to 4 is provided, the influence of thermal expansion of the indenter shaft on the material properties of the sample can be reduced. it can.

According to the sixth aspect of the present invention, the same effect as that of the fifth aspect of the invention can be obtained. Under the circumstances where the indenter shaft is easily heated or cooled (that is, the conventional indenter shaft). In such a case, measurement for evaluating the material properties of the sample may be performed in a situation where thermal expansion or thermal contraction is likely to occur, so that the effect of the present invention can be further exhibited.

Hereinafter, the best mode of a material testing machine according to the present invention will be described in detail with reference to the drawings. The scope of the invention is not limited to the illustrated example.
In the present embodiment, a hardness tester will be described as an example of the material tester.

For example, the hardness tester 1 pushes the indenter 21 of the indenter shaft 2 into the surface of the sample S to form a recess, and evaluates a predetermined material property of the sample S based on the recess.
Specifically, for example, as shown in FIG. 1, the hardness tester 1 detects a temperature of a sample stage 11 on which the sample S is placed and a temperature in the vicinity of the sample S placed on the sample stage 11. The temperature detection unit 12 as a means, the heating / cooling unit 13 for heating or cooling the sample stage 11, and the heating / cooling unit 13 are controlled based on the temperature detected by the temperature detection unit 12, and the temperature of the sample stage 11 is set. When the indenter is formed by the indenter shaft 2, the indenter shaft 2 that forms a recess in the sample S, the load loading mechanism unit 3 that applies a predetermined test force to the indenter shaft 2, and the indenter formation A displacement meter 4 that measures the indentation depth of the shaft 2 and a control processing unit that controls the load loading mechanism 3 and the displacement meter 4 or processes data obtained by the load loading mechanism 3 and the displacement meter 4 7 and the like.

The sample stage 11 is disposed, for example, below the indenter shaft 2 and includes a temperature detection unit 12 and a heating / cooling unit 13.
For example, the temperature detection unit 12 detects the temperature in the vicinity of the sample S placed on the sample stage 11 in accordance with a control signal input from the control unit 14, and outputs data regarding the detected temperature to the control unit 14.
For example, the heating / cooling unit 13 heats or cools the sample stage 11 in accordance with a control signal input from the control unit 14.

  For example, the control unit 14 inputs a predetermined control signal to the temperature detection unit 12 to detect the temperature in the vicinity of the sample S, and based on the data related to the temperature output from the temperature detection unit 12, the heating / cooling unit 13. The sample stage 11 is heated or cooled by inputting a predetermined control signal to.

  For example, as shown in FIG. 2, the indenter shaft 2 includes an indenter 21 for forming a recess in the sample S, and an indenter shaft body 22 having the indenter 21 attached to the tip.

The indenter 21 is made of, for example, diamond or sapphire.
The material forming the indenter 21 is not limited to diamond or sapphire, but is a material suitable as an indenter, and any material having an absolute value of thermal expansion coefficient that is comparable to or smaller than that of diamond or sapphire. Is optional.

The indenter shaft body 22 is, for example, a material suitable as a part for a load test, and has an absolute value of a thermal expansion coefficient greater than that of stainless steel (for example, SUS304 (thermal expansion coefficient: 17.3 × 10 ⁻⁶ / ° C.)). Is made of a small material.
Specifically, the indenter shaft main body 22 includes, for example, Super Invar (manufactured by Mitsubishi Materials Corporation [MA-S-INVER], thermal expansion coefficient: 0 to 1.5 × 10 ⁻⁶ / ° C.), alumina (Sumikin Ceramics, [AF999] manufactured by And Quartz Co., Ltd., coefficient of thermal expansion: 7.1 × 10 ⁻⁶ / ° C., aluminum nitride (ALN94) manufactured by Sumikin Ceramics & Quartz Co., Ltd., coefficient of thermal expansion: 4.4 × 10 ⁻⁶ / C), synthetic quartz (manufactured by Asahi Glass Co., Ltd., coefficient of thermal expansion: 0.6 × 10 ⁻⁶ / ° C.), and the like.

The load load mechanism unit 3 includes, for example, a piezoelectric element, a force coil, and the like as a drive source (not shown).
Specifically, the load load mechanism unit 3 generates a predetermined test force by a drive source (not shown) in accordance with a control signal input from the control processing unit 7, for example, and the generated test force is indented. By loading the shaft 2 (indenter shaft body 22), the indenter shaft 2 (indenter 21) is loaded with a predetermined load on the sample S, and data relating to the generated predetermined test force is sent to the control processing unit 7. Output.

The displacement meter 4 is, for example, the indentation depth of the indenter shaft 2 with respect to the sample S when a predetermined test force is applied to the indenter shaft 2 by the load load mechanism unit 3 in accordance with a control signal input from the control processing unit 7. , And outputs data relating to the measured indentation depth to the control processing unit 7.
Specifically, the displacement meter 4 measures the indentation depth of the indenter shaft 2 with respect to the sample S, for example, by detecting the displacement of the displacement detection reference in the indenter shaft 2.

  The control processing unit 7 measures the indentation depth of the indenter shaft 2 by inputting a predetermined control signal to the load load mechanism unit 3 and the displacement meter 4, for example. During the measurement, for example, data relating to the test force from the load loading mechanism portion 3 and data relating to the indentation depth from the displacement meter 4 are output to the control processing portion 7 in synchronization with each other. Then, the control processing unit 7 evaluates a predetermined material property of the sample S by calculating a physical property value such as hardness of the sample S from the output data regarding the test force and data regarding the indentation depth. .

  According to the hardness testing machine 1 of the present invention described above, the indenter shaft body 22 is made of a material having a smaller thermal expansion coefficient than that of stainless steel conventionally used as an indenter shaft body (super invar, alumina, The indenter shaft 2 is less likely to be thermally expanded (or thermally contracted) as compared with the conventional case, and the heat of the indenter shaft 2 for the evaluation of the material characteristics of the sample S is reduced. The influence of expansion can be reduced.

  For example, when the indenter shaft main body 22 is formed of super invar, the super invar has not only a small thermal expansion coefficient but also excellent workability, so that the indenter shaft main body 22 that can be easily molded Become.

  For example, when the indenter shaft body 22 is made of alumina, the alumina is not only small in thermal expansion coefficient, but also high in rigidity and low in price, and therefore suitable for high load test parts. In addition, the indenter shaft main body 22 can reduce the cost burden.

  For example, when the indenter shaft body 22 is formed of aluminum nitride, the aluminum nitride not only has a small thermal expansion coefficient but also has a high rigidity, so that it becomes an indenter shaft body 22 suitable for parts for high load tests. .

  Further, for example, when the indenter shaft body 22 is formed of synthetic quartz, the synthetic quartz has a smaller thermal expansion coefficient, so that the indenter shaft 2 is more difficult to thermally expand compared to the conventional case. The indenter shaft body 22 can further reduce the influence of thermal expansion of the indenter shaft 2.

  Since the hardness tester 1 includes the heating / cooling unit 13 and the like, the indenter shaft 2 is easily heated or cooled (that is, the conventional indenter shaft is likely to be thermally expanded or contracted). ), A measurement for evaluating the material properties of the sample S may be performed, so that the effect of the present invention can be further exhibited.

[Modification]
Next, a modification of the indenter shaft 2 (indenter shaft 2a) will be described.

  For example, as shown in FIG. 3, the indenter shaft 2 a includes an indenter 21 a that forms a recess in the sample S, and an indenter shaft main body 22 a that has an indenter 21 a attached to the tip.

The indenter 21a is made of, for example, a material having a positive thermal expansion coefficient.
Specifically, the indenter 21a is made of, for example, diamond or sapphire.
The material for forming the indenter 21a is not limited to diamond or sapphire, but is a material suitable as an indenter, and any material having an absolute value of thermal expansion coefficient that is comparable to or smaller than that of diamond or sapphire. Is optional.

For example, at least a part of the indenter shaft main body 22a is formed of a material having a negative coefficient of thermal expansion. That is, the indenter shaft main body 22a is, for example, as shown in FIG. 3A, a first indenter shaft main body that is made of a material suitable for a load test component and that has a negative thermal expansion coefficient. The first indenter shaft main body 22a1 and a material suitable as a load test component as shown in FIG. 3B, for example, as shown in FIG. And a second indenter shaft body 22a2 formed of a material having a small absolute value of the coefficient.
Specifically, the first indenter shaft body 22a1 is made of, for example, hexagonal boron nitride, aluminum titanate, or the like.
The second indenter shaft main body 22a2 is formed of, for example, super invar, alumina, aluminum nitride, synthetic quartz, or the like.

For example, if the length in the pushing direction from the tip of the indenter shaft 2a to the displacement detection reference is L, the length in the pushing direction of the indenter 21a is L1, and the length in the pushing direction of the first indenter shaft body 22a1 is L2. , L1 and L2 are the product of L1 and the thermal expansion coefficient of the material forming the indenter 21a (diamond (thermal expansion coefficient: 0.8 × 10 ⁻⁶ / ° C.)) while the sum of L1 and L2 is L or less. And the product of the thermal expansion coefficient of the material forming the first indenter shaft main body 22a1 and L2 is set to be zero.
When the sum of L1 and L2 is the same as L, the indenter shaft main body 22a is configured by only the first indenter shaft main body 22a1, for example, as shown in FIG.
On the other hand, when the sum of L1 and L2 is smaller than L, in order to compensate for the difference, the second indenter shaft body 22a2 (length L3) is added, and the indenter shaft body 22a is replaced with, for example, FIG. As shown to (b), it comprises with the 1st indenter shaft main body 22a1 and the 2nd indenter shaft main body 22a2.
That is, whether the indenter shaft main body 22a is composed of only the first indenter shaft main body 22a1 or whether it is composed of the first indenter shaft main body 22a1 and the second indenter shaft main body 22a2, L, L1, It depends on the thermal expansion coefficient of the material forming the first indenter shaft body 22a1.

More specifically, for example, assuming that the temperature of the indenter 21 (indenter shaft 2) is uniform, L is 7.5 mm, L1 is 1.5 mm, and the first indenter shaft body 22a1 is hexagonal boron nitride (Mitsui). L2 is 6.0 mm, and the sum of L1 and L2 (7.5 mm) is the same as L when formed with Mine Material Co., Ltd. (thermal expansion coefficient: −0.2 × 10 ⁻⁶ / ° C.). Therefore, in this case, the indenter shaft main body 22a is constituted only by the first indenter shaft main body 22a1.
On the other hand, for example, assuming that the temperature of the indenter 21 (indenter shaft 2) is uniform, L is 7.5 mm, L1 is 2.0 mm, and the first indenter shaft body 22a1 is made of aluminum titanate (Asahi Glass Ceramic Co., Ltd.). , Thermal expansion coefficient: -0.5 × 10 ⁻⁶ / ° C.) L2 is 3.2 mm, and the sum of L1 and L2 (5.2 mm) is smaller than L, so the difference (2.3 mm) is In order to compensate, a second indenter shaft body 22a2 having a length in the pushing direction of 2.3 mm is added. Therefore, in this case, the indenter shaft main body 22a is constituted by the first indenter shaft main body 22a1 and the second indenter shaft main body 22a2.

  According to the modification described above, at least a part of the indenter shaft main body 22a (first indenter shaft main body 22a1) is formed of a material having a negative thermal expansion coefficient (such as hexagonal boron nitride or aluminum titanate). Therefore, the thermal expansion of the indenter 21a formed of a material having a positive thermal expansion coefficient (diamond or sapphire) can be offset, and the influence of the thermal expansion of the indenter shaft 2a on the evaluation of the material characteristics of the sample can be reduced. Can be reduced.

  When the first indenter shaft body 22a1 is formed of hexagonal boron nitride, the hexagonal boron nitride not only has a negative thermal expansion coefficient, but also has excellent workability and is non-oxidizing. The first indenter shaft body 22a1 can be easily formed and has high durability.

  Further, when the first indenter shaft main body 22a1 is formed of aluminum titanate, the aluminum titanate not only has a negative thermal expansion coefficient, but also has excellent workability and high corrosion resistance, so that it is easily molded. Thus, the first indenter shaft main body 22a1 having high durability can be obtained.

The present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the gist thereof.
For example, in the modification, L1 and L2 are set considering only the thermal expansion (or thermal contraction) of the indenter shaft 2a. For example, the thermal expansion (or thermal contraction) of components around the indenter shaft 2a is set. You may make it set in consideration.

  For example, in a modification, the indenter 21a is formed of a material having a positive thermal expansion coefficient, the first indenter shaft main body 22a1 is formed of a material having a negative thermal expansion coefficient, and the second indenter shaft main body 22a2 is formed of a thermal expansion coefficient. However, the material for forming the indenter 21a, the first indenter shaft main body 22a1, and the second indenter shaft main body 22a2 is not limited to this. That is, when the length of the second indenter shaft main body 22a2 in the pushing direction is L3, the sum of L1, L2, and L3 is the same as L, and the thermal expansion coefficient of the material forming the indenter 21a and L1 And the product of the thermal expansion coefficient of the material forming the first indenter shaft body 22a1 and L2, and the product of the thermal expansion coefficient of the material forming the second indenter shaft body 22a2 and L3 are zero. As long as the material is suitable as a load test component, the material forming the indenter 21a, the first indenter shaft body 22a1, and the second indenter shaft body 22a2 is arbitrary.

  The configuration of the hardness tester 1 is not limited to the present embodiment, and includes, for example, a load lever having an indenter shaft at one end and a force coil that generates electromagnetic force at the other end. It may be a hardness tester configured as described above.

It is a figure which shows the principal part structure of the material testing machine (hardness testing machine) concerning this invention. It is a figure which shows sectional drawing of the indenter axis | shaft with which the material testing machine (hardness testing machine) concerning this invention was equipped. It is a figure which shows sectional drawing of the indenter shaft concerning a modification.

Explanation of symbols

1 Hardness testing machine (material testing machine)
2, 2a Indenter shaft 21, 21a Indenter 22, 22a Indenter shaft body 11 Sample stand 12 Temperature detector (temperature detector)
13 Heating / cooling unit 14 Control unit (control means)
S sample

Claims (6)

In the indenter shaft in which the indenter is provided at the tip of the indenter shaft body,
2. The indenter shaft according to claim 1, wherein the indenter shaft body is formed of super invar having a smaller thermal expansion coefficient than stainless steel. In the indenter shaft provided with an indenter formed of a material having a positive coefficient of thermal expansion at the tip of the indenter shaft body,
The indenter shaft body includes a first indenter shaft body formed of a material having a negative thermal expansion coefficient, and a second indenter shaft body formed of a material having a positive thermal expansion coefficient,
The sum of the length in the pushing direction of the indenter, the length in the pushing direction of the first indenter shaft body, and the length in the pushing direction of the second indenter shaft body is the pushing direction from the tip of the indenter to the displacement detection reference. An indenter shaft characterized by being set to be equal to the length of The indenter shaft according to claim 2 ,
The indenter shaft, wherein the material having a negative coefficient of thermal expansion is hexagonal boron nitride. The indenter shaft according to claim 2 ,
The indenter shaft, wherein the material having a negative coefficient of thermal expansion is aluminum titanate. A material testing machine characterized in that the indenter of the indenter shaft according to any one of claims 1 to 4 is pushed into a sample surface to form a recess, and a predetermined material property of the sample is evaluated based on the recess. . The material testing machine according to claim 5 ,
A sample stage on which the sample is placed;
A heating / cooling section for heating or cooling the sample stage;
Temperature detecting means for detecting the temperature in the vicinity of the sample placed on the sample stage;
Control means for controlling the heating and cooling unit based on the temperature detected by the temperature detection means to control the temperature of the sample stage;
A material testing machine comprising:

Images