JP2011112629A - Indentor for measuring hardness and method of measuring hardness using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an indentor for measuring hardness for measuring hardness of an object to be measured easily. <P>SOLUTION: The indentor 10 is for measuring hardness of the object 90 to be measured. The indentor 10 includes: an indentor body 11 including a tip 110 reduced in diameter; and a coating layer 15 coating the surface of the tip 110. When the tip 110 is pressed to the object 90 to be measured in measurement of hardness, the coating layer 15 for covering a hollow part 12 in the tip 110 hollowing the object 90 to be measured disappears. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an indenter used for measuring the hardness of an object to be measured and a hardness measuring method using the indenter. In particular, the present invention relates to an indenter used in a hardness measurement method using the disappearance amount of a coating layer provided on the surface of the indenter as an index, and a hardness measurement method using the indenter.

  When a dental hard tissue (enamel, dentin) suffers from caries, the dental hard tissue loses its original hardness and softens. Although it is necessary to remove the softened tooth hard tissue, the softened tooth hard tissue can be preserved. Therefore, it is very important to know the degree of softening (that is, measure the hardness) when deleting caries lesions (caries treatment).

  There are a wide variety of hardness measuring instruments in the world that are available on the market. Generally, when measuring the hardness of a tooth, the extracted tooth is half-cut and polished, and then a test table for a micro hardness tester. And press the diamond indenter with a constant load to make an indentation. The indentation width is magnified 400 times with a microscope and measured with a micrometer. The obtained indentation width (μm) is converted into hardness (Knoop hardness) using a conversion table. In addition to the stationary microhardness meter used in these laboratories, there is a portable hardness meter. However, it is not possible to measure small tissues such as dental caries, and it is absolutely impossible to use it for teeth in the oral cavity.

  As a method that can determine the hardness in the oral cavity, a method has been reported in which the hardness is determined based on whether or not a tag back is detected when the conical sapphire indenter is pressed against the carious part with a constant load and pulled apart. (For example, see Patent Documents 1 and 2). When the probe is pushed into a softened area such as a carious lesion and pulled up, a phenomenon (tagback) in which the probe is pulled by the carious tooth occurs. The traction force of the probe due to the tag back is generated when the object to be measured is soft. In Patent Documents 1 and 2, using such a relationship between hardness and traction force, the probe is pushed into the caries portion to check the presence or absence of tag back, so that it is possible to discriminate between hardness and softness.

JP 2003-319950 A JP 2008-29412 A

  In the measurement methods using the tag backs of Patent Documents 1 and 2, it is possible to determine whether the hardness is softer or softer than a predetermined hardness (for example, Knoop hardness 20), but the hardness itself cannot be measured.

  As another method to know the hardness itself, take a precise impression of the impression given to the caries, create a replica model, measure the diameter of the impression with a microscope, and use the conversion graph to determine the hardness (Knoop hardness) ) Has been reported. However, this method requires a replica model creation step in addition to a general Knoop hardness measurement step (indentation, indentation measurement, hardness conversion). This complicates the measurement procedure. In addition, the measurement time becomes longer due to the creation of the replica model.

  Therefore, an object of the present invention is to provide a hardness measuring indenter that can easily measure the hardness of a carious lesion and is excellent in practicality, and a hardness measuring method using the same.

The present invention is an indenter for measuring the hardness of an object to be measured,
The indenter is
An indenter body with a reduced diameter tip,
An application layer applied to the surface of the tip,
When the tip is pressed against the object to be measured at the time of hardness measurement, the coating layer covering the indented portion of the tip that is invaded into the object to be measured disappears.

The present invention is a hardness measurement method for measuring the hardness of an object to be measured using the hardness measurement indenter,
A pressing step of pressing the indenter against the object to be measured at a predetermined pressure, and causing the tip of the indenter body to intrude into the object to be measured;
A measuring step for measuring the length of the invaginated portion where the coating layer has disappeared;
And a hardness conversion step of determining the hardness of the object to be measured based on the pressure and the length of the indented portion.

In this specification, “the coating layer disappears” refers to a state in which the coating layer covering the indented portion is removed by the object to be measured and the indenter body is exposed from the indented portion.
The coating layer removed from the indented portion may move to the object to be measured, or may move to a portion other than the indented portion (non-indented portion) of the indenter body.

Using the hardness measurement indenter according to the present invention, the hardness of the object to be measured can be measured by the hardness measurement method according to the present invention.
That is, in the “pressing step” of the measuring method of the present invention, the tip portion of the indenter body is provided on the surface of the tip portion when pressed against the object to be measured with a predetermined pressure (indented). Of the coating layer, only the coating layer that is invaded into the object to be measured disappears. Then, in the “measuring step”, the length of the portion (invaded portion) where the coating layer has disappeared is measured. The length of the indented part coincides with the depth at which the indenter body intruded into the object to be measured in the pressing process. Therefore, if the length of the indented part is measured, the indenter body is indented by the same depth as the indented part. I understand that I was doing. Finally, in the “hardness conversion step”, the hardness is determined based on the length of the intrusion portion (indentation depth) obtained in the “measurement step” and the predetermined pressure applied to the indenter in the “pressing step”. (For example, Knoop hardness KHN).

When the hardness measurement is performed using the hardness measurement indenter of the present invention, the hardness itself can be obtained instead of the mere hardness.
Moreover, in the hardness measurement of the present invention using the indenter for hardness measurement of the present invention, “indentation length measurement” is performed instead of “measurement of indentation” in general Knoop hardness measurement. . That is, when the hardness measurement of the present invention is compared with a general Knoop hardness measurement, the hardness can be measured with the same number of steps. Therefore, if the hardness of the carious lesion is measured using the indenter of the present invention, the hardness of the carious lesion can be measured without an additional step (creation of a replica model).

FIG. 1 shows a hardness measurement indenter according to the first embodiment. 1A is a perspective view of the indenter, FIG. 1B is a longitudinal sectional view of the indenter at X ₁ -X ₁ shown in FIG. 1A, and FIG. 1C is FIG. ) is a plan view of the indenter observed from the arrow X ₂ direction shown in. FIG. 2 is a schematic diagram for explaining hardness measurement using the hardness measurement indenter shown in FIG. 1 (ac). FIG. 3 shows the indenter for measuring the hardness after being inserted into the object to be measured. 3A is a perspective view of the indenter, FIG. 3B is a longitudinal sectional view of the indenter at Y ₁ -Y ₁ shown in FIG. 3A, and FIG. 3C is FIG. ) is a plan view of the indenter observed from the arrow Y ₂ direction shown in. FIG. 4 is a length-hardness calibration curve of the invaginated portion created from the indenter for hardness measurement shown in FIG. FIG. 5 is a flowchart for explaining the measurement procedure when the hardness measurement is performed using the measurement program and the hardness conversion program. FIG. 6 is a schematic diagram for explaining a state in which the indenter for hardness measurement shown in FIG. FIG. 7 is a schematic perspective view for explaining a manufacturing process of the hardness measurement indenter of FIG. 1 (ac). FIG. 8 is an enlarged view of the tip of the hardness measurement indenter (after indentation) (a, b). FIG. 9 shows the hardness measurement indenter according to the first embodiment. 9A is a perspective view of the indenter, FIG. 9B is a longitudinal sectional view of the indenter at Z ₁ -Z ₁ shown in FIG. 9A, and FIG. 9C is FIG. ) is a plan view of the indenter observed from the arrow X ₂ direction shown in. FIG. 10 is a schematic view for explaining a handy type hardness measurement system using the hardness measurement indenter of the present invention. FIG. 11 is a schematic perspective view of the handpiece shown in FIG. FIG. 12 is a schematic cross-sectional view of the handpiece shown in FIG. FIG. 13 is a schematic perspective view of the microscope shown in FIG. 14 is a schematic perspective view of the indenter base shown in FIG. 13 (a, b). FIG. 15 is a schematic view for explaining an installation type pressing device using the indenter for hardness measurement of the present invention. FIG. 16 is a microscopic image of a hardness measurement indenter that has invaginated in the carious tooth extracted in Example 1. FIG. 17 is a microscopic image of a hardness measurement indenter that has been indented into a plastic plate in Example 2.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following description, terms indicating specific directions and positions (for example, “up”, “down”, “right”, “left” and other terms including those terms) are used as necessary. . The use of these terms is to facilitate understanding of the invention with reference to the drawings, and the technical scope of the present invention is not limited by the meaning of these terms. Moreover, the part of the same code | symbol which appears in several drawing shows the same part or member.

<Embodiment 1>
In the present embodiment, an indenter suitable for measuring the hardness of oral teeth and extracted teeth (for example, carious lesions) will be described.
1A to 1C show a hardness measuring indenter 10 (hereinafter referred to as “indenter 10”) according to the present invention. The indenter 10 includes an indenter body 11 and a coating layer 15. The indenter body 11 includes a tip portion 110 with a reduced diameter, and the surface of the tip portion 110 is covered with a coating layer 15. The coating layer 15 covers a part or all of the distal end portion 110 from the apex 116 of the distal end portion 110 of the indenter body 11 (in the figure, a portion of the distal end portion 110 is covered). For ease of explanation, the thickness of the coating layer 15 is shown to be thicker than the actual thickness.

Specifically, the hardness measurement using the indenter 10 of the present invention includes the following three steps.
(1) Pressing step The tip 16 of the indenter 10 is applied to an object to be measured (for example, a tooth), the indenter 10 is pressed until the pressure applied to the indenter 10 reaches a predetermined value, and the tip 110 of the indenter body 11 is measured. Intrude into things. At this time, the coating layer 15 covering the portion (indented portion) indented in the object to be measured in the tip portion 110 peels off and moves to the object to be measured. That is, the coating layer 15 is removed from the surface of the indented portion by the pressing step.
(2) Measurement process The length of the intrusion portion (portion from which the coating layer 15 has been removed) is measured with a measurement means (for example, a measurement microscope).
(3) Hardness conversion step Using the “predetermined value of pressure” in the pressing step and the “length of the indented portion” measured in the measurement step, the hardness is converted into the measured object.
Below, each process is demonstrated concretely.

(1) Pressing Step FIG. 2A shows a state before the tip 16 of the indenter 10 contacts the object to be measured (for example, teeth) 90, and FIG. And FIG. 2C shows a state in which the pressure applied to the indenter 10 has reached a predetermined value. In FIG. 2, when the pressure applied to the indenter 10 is equal to or lower than a predetermined value, the lamp 81 is extinguished (FIGS. 2A and 2B), and the lamp 81 is turned on when the predetermined value is reached ( FIG. 2 (c)).

  In addition, since the indenter 10 has a diameter of about several millimeters, it is difficult to hold and press it with a finger. Therefore, it is preferable to use a pressing instrument for holding the indenter 10 and pressing the indenter 10 against the object 90 to be measured.

  2B and 2C, a part of the tip portion 110 of the indenter main body 11 is recessed into the object 90 to be measured. The coating layer 15 covering the indented portion 12 is peeled off by the measurement object 90. The peeled coating layer 150 adheres to the surface 91 of the object to be measured 90 (around the indenter 10).

  As shown in FIG. 2C, when the pressure applied to the indenter 10 reaches a predetermined value, the pressing of the indenter 10 is finished, and the indenter 10 is removed from the object 90 to be measured. The indentation depth of the invaginated portion 12 at the time when the pressing is finished is indicated by “reference sign D”.

(2) Measuring process The indenter 10 after the above pressing process is completed is a part of the coating layer 15 that covers the tip 110 of the indenter body 11 as shown in FIGS. 3 (a) to 3 (c). Is peeled off and the apex 116 of the tip 110 is exposed. This exposed portion coincides with the “depression portion 12” of the pressing process.
In this way, the length L of the invaginated portion 12 is measured by observing the indenter 10 where the apex 116 of the distal end portion 110 is exposed with a microscope (for example, a measuring microscope with a magnification of 400). The “length of the indented portion 12” refers to the size of the indented portion measured along the direction of the long axis 13 of the indenter 10.
Since the length L of the invaginated portion 12 is equal to the indentation depth D, the indentation depth D can be known by measuring the length L. In the present specification, the “length L of the invaginated portion 12” can be regarded as substantially indicating the “indentation depth D”.

(3) Hardness conversion step FIG. 4 is a length-hardness indicating the relationship between the length of the indented portion 12 when a predetermined pressure (for example, 150 gf) is applied to the indenter 10 and the hardness of the object 90 to be measured. This is a calibration curve. Five kinds of measured objects 90 having known hardness (in the example of FIG. 4, Knoop hardness 5, 6, 13.5, 21 and 30.5) are prepared, and the indenter 10 is moved to a predetermined pressure (150 gf) in step (1). The length L (indentation depth D) of the invaginated portion 12 was measured in step (2). The calibration curve of FIG. 4 was created from the hardness of each measurement object 90 and the length L of the invaginated portion 12.

And even with the object 90 whose hardness is unknown, the indenter 10 is pressed to the same predetermined pressure (150 gf) in the step (1), and the length L (that is, the indentation depth) of the indented portion 12 in the step (2). D) is measured. The obtained “length L” value is converted into hardness using the calibration curve of FIG.
The calibration curve differs depending on the radius of curvature of the apex 116 of the tip portion 110 of the indenter body 11 to be used and the internal holding angle θ (FIG. 3) of the tip portion 110, and is therefore the same as that of the indenter 10 used for actual measurement. It is necessary to prepare a calibration curve using the one.

As described above, the hardness of the DUT 90 can be measured by performing the steps (1) to (3) using the indenter 10 of the present invention.
Moreover, if a microscope and a calibration curve are prepared near the place where the pressing process is performed (that is, the place where the object to be measured is placed), all of the processes (1) to (3) can be performed continuously. it can. That is, since the indenter is pushed into the object to be measured, the length of the indented portion is measured immediately thereafter, and the hardness can be obtained from the result, so that the hardness can be measured in real time.

  Furthermore, if an automated system including a computer, a microscope that can be connected to the computer, and a “measurement program” and a “hardness conversion program” that operate on the computer is constructed as a system for measuring hardness, a process ( 3) can also be automated.

  “Measurement program” refers to a program that can measure the actual dimensions of a target portion from image data from a microscope. For example, the image data of the indented portion 12 of the indenter body 10 is displayed on the display, and the apex 116 of the tip portion 110 of the indenter body 10 and two arbitrary points on the boundary line between the tip portion 110 and the coating layer 15; If a total of three points are designated, a measurement program that can calculate the distance between the vertex 116 and the boundary line (that is, the length L of the invaded portion 12) can be used.

  “Hardness conversion program” refers to a program that converts length to hardness using a number of “length-hardness” data pairs on the calibration curve or the calculation formula of the calibration curve. Say. That is, when the numerical data of the length L of the intrusion portion 12 is input to the hardness conversion program, the numerical data of the hardness of the workpiece 90 can be obtained.

The operation of the automation system will be specifically described below with reference to FIG.
First, image data from a microscope is input to a computer (S10), and the image data is displayed on a display (S20).

(Process (2))
By using the function of the “measurement program” operating on the same computer, the measurement reference points (3 points: the apex 116 of the tip 110 of the indenter body 10, the tip 110 and the coating layer 15 are (Arbitrary two points on the boundary line) are set (S30). The measurement program calculates the length L of the invaginated portion 12 from the three points (S40) and outputs it as length data (S50). The length data is stored in a computer memory or the like.

(Process (3))
Next, the length data is input to the “hardness conversion program” operating on the same computer (S60). At this time, the hardness conversion program may be programmed so as to automatically refer to the length data stored in the memory or the like. The hardness conversion program converts the length data (length L) into hardness (S70). This hardness data is output to display means such as a display (S80). The measurer who measures the hardness can know the hardness of the object to be measured from the displayed “hardness”.
Thus, the process (3) can be automated by using the “measurement program” and the “hardness conversion program”.

  In addition, although the example which combined the "measurement program" and the "hardness conversion program" was shown above, in order to calculate the length L, a "measurement program" can be used independently (another method In order to convert the length L (calculated in step 1) into hardness, the “hardness conversion program” can be used alone.

By the way, in the step (1), it is desirable to press the indenter 10 against the measurement object 90 so that the long axis 13 of the indenter 10 is perpendicular to the surface 91 of the measurement object 90. However, when the major axis 13 is not perpendicular to the surface 91 as shown in FIG. 6, the length L (corresponding to the indentation depth D) of the indented portion 12 varies depending on the position to be measured. In such a case, the maximum length L ₁ and the minimum length L ₂ of the invaginated portion 12 are measured, and the average length ((L ₁ + L ₂ ) / 2) is determined as “the indented portion 12. It is assumed that the length is “L”.

Below, the manufacturing method of the indenter 10 is demonstrated, referring FIG.
First, a rod-shaped member 111 having a predetermined dimension (for example, a diameter of 1 mm and a length of 5 mm) is produced from a material used for the indenter body 11 (FIG. 7A).
Then, one end of the rod-shaped member 111 is tapered with the long axis 130 of the rod-shaped member 111 as the central axis (FIG. 7B). Thereby, the diameter-reduced front-end | tip part 110 is formed in the rod-shaped member 111 (indenter main body 11). Further, if necessary, the apex 116 of the distal end portion 110 is processed and given R.
When the indenter body 11 is formed of a metal material, in addition to the above method, the indenter body 11 shown in FIG. 7B may be directly cast using a mold having the shape of the indenter body 11. it can.

Finally, a coating layer coating agent (paint, semi-solid material, etc.) is applied to the tip 110 of the indenter body 11 to form the coating layer 15 (FIG. 7C). For applying the coating agent, a known coating method such as a method of applying with a brush or the like, a method of immersing the tip 110 of the indenter body 11 in the coating agent (dip coating), or the like can be used. Moreover, if it is a coating agent provided with a pen type, it can also apply directly to the front-end | tip part 110 of the indenter main body 11. FIG.
Moreover, if all the coating layers 15 are peeled from the indenter 10 after use, it can be reused as the indenter body 11 in FIG.

  Next, a specific configuration of the indenter 10 for hardness measurement according to the present invention will be described in detail.

(Indenter body 11)
The indenter body 11 can be formed of a hard material such as metal, ceramic, ore. In particular, it is preferable to form the indenter body 11 from a hard material having a Knoop hardness of 200 or more because hardness of various materials (for example, teeth, metal, metal coating layer, plastic, plastic coating layer, etc.) can be measured. In general, the surface of the tip 110 of the indenter body 11 is mirror-polished.

  Examples of the ore having a Knoop hardness of 200 or more suitable for the indenter body 11 include natural or artificial minerals such as diamond, sapphire, ruby, and zircon. In particular, since sapphire has high hardness, it can be used for measuring the hardness of many objects to be measured. In addition, sapphire is easier to process and less expensive than diamond, so the cost of the indenter body 11 can be reduced.

  Further, when the indenter body 11 is formed from a transparent ore, it becomes easy to confirm the boundary of the indented portion 12 when combined with the opaque coating layer 15. Therefore, there is an advantage that the measurement accuracy of the length L (that is, the indentation depth D) of the invaginated portion 12 can be improved. That is, when an indenter in which the indenter body 11 made of a transparent ore and the opaque coating layer 15 are combined is used, an effect of improving measurement accuracy in hardness measurement can be obtained.

Examples of the metal having a Knoop hardness of 200 or more suitable for the indenter body 11 include cemented carbides such as WC-Co, WC-TaC-Co, WC-TiC-Co, and WC-TiC-TaC-Co.
Moreover, since the indenter body 11 formed of cemented carbide has an opaque dark color, it becomes easy to confirm the boundary of the indented portion 12 when combined with an opaque coating layer 15 having a high lightness (white). Therefore, there is an advantage that the measurement accuracy of the length L (that is, the indentation depth D) of the invaginated portion 12 can be improved. That is, when an indenter in which the indenter body 11 made of a cemented carbide and the opaque coating layer 15 having high brightness are used is used, an effect of improving measurement accuracy in hardness measurement can be obtained.

  The tip 110 of the indenter body 11 is reduced in diameter so as to have an appropriate internal holding angle θ (FIG. 3B). The preferred internal obtuse angle θ varies depending on the material of the object 90 to be measured. Therefore, it is most desirable to use the indenter 10 having the optimum inner holding angle θ in accordance with the object 90 to be measured. However, when it is difficult to prepare many types of indenters 10 or when it is desired to prepare versatile indenters 10, it is possible to prevent chipping of the apex 116 of the distal end portion 110 and to easily push it into the object 90 to be measured. In view of this, it is preferable to use the indenter 10 having an internal obtuse angle in the range of θ = 30 to 90 °.

Furthermore, it is preferable to add R to the apex 116 ′ of the indenter body 11 as shown in FIG. 8B (beveling the apex) because chipping is less likely than the sharp apex 116 as shown in FIG. 8A. . The radius of curvature of R at the apex 116 ′ is preferably in the range of 0.3 to 1.0 mil (7.5 to 25 μm). When the radius of curvature is within the range, there is no problem in pushing the indenter 10 into the object 90 to be measured, and there is an effect in suppressing chipping of the tip 16 '.
Note that the length L (indentation depth D) of the intrusion portion 12 is an actual length measured from the vertices 116 and 116 ′. That is, the length L of the invaginated portion 12 is “length L ₃ ” in FIG. 8A and “length L ₄ ” in FIG.

(Coating layer 15)
The properties required for the coating layer 15 are: (a) good coating property to the indenter body 11, (b) peelability from the indenter body 11, and (c) adhesion to the measured object 90. Is required. Each property will be described in detail below.

(A) Good applicability to the indenter body 11 “Good applicability” in this specification means that the coating agent for the coating layer can be applied to the entire surface of the indenter body 11.
When the coating agent for the coating layer is applied to the tip portion 110 of the indenter body 11, if the coating agent does not have sufficient wettability with respect to the surface of the indenter body 11, the coating agent is applied to the surface of the indenter body 11. It is bounced and cannot spread over the entire surface. As a result, the obtained coating layer 15 may not only have a non-uniform film thickness but also a film with holes. With such a coating layer 15, the length L (indentation depth D) of the indented portion 12 cannot be measured accurately. Therefore, the coating agent for the coating layer is required to have sufficient wettability with respect to the surface of the indenter body 11.

  The wettability is affected by the type of coating agent (type of paint solvent and pigment, type of semi-solid material, etc.). Therefore, it is desirable to select the coating agent according to the material of the indenter body 11 to be used.

(B) Peelability from the indenter body 11 “Peelability” required for the coating layer 15 of the present invention means that the coating layer does not peel until the indenter 10 is pressed against the measured object 90, and the indenter 10 is measured. When the object 90 is invaded, the coating layer 15 of the intruded portion 12 is peeled off.
The peelability mainly depends on the bonding force between the coating layer 15 and the tip 110 of the indenter body 11. This binding force is affected by the type of coating agent, the material of the indenter body 11, the surface properties of the tip 110, and the like. Therefore, when selecting the coating agent for the coating layer and selecting the material of the indenter body 11, it is necessary to consider releasability.

(C) Adhesiveness to the measurement object 90 If the coating layer 150 peeled off from the indenter 10 remains attached to the tip 110 of the indenter body 11, the indented portion 12 is not easily formed clearly. Therefore, an error is likely to occur in the measurement of the length L (indentation depth D) of the indented portion 12. Therefore, it is desirable to select the coating agent for the coating layer so that the coating layer 15 easily moves to the object to be measured 90 after being peeled off.

  In consideration of the above performances (a) to (c), it is desirable to determine the material of the indenter body 11 (such as paint solvent and pigment types, semi-solid material types).

  Examples of the coating agent for forming the coating layer 15 include a solvent type coating agent and a non-solvent type coating agent. The solvent-type coating agent refers to a paint in which a pigment or dye is dispersed in a solvent. When the solvent-type coating agent is applied to the tip 110 of the indenter body 11, the solvent evaporates and the pigment or paint forms the coating layer 15. The non-solvent coating agent refers to a coating agent that does not contain a solvent. When the non-solvent coating agent is applied to the tip 110 of the indenter body 11, the non-solvent coating agent itself forms the coating layer 15.

First, the coating layer 15 using a solvent-type coating agent will be described.
A solvent-type coating agent suitable for the present invention includes a paint prepared by dispersing a pigment in a solvent. When the solvent is volatilized after application of the paint, the pigment adheres to the application surface (the tip 110 of the indenter body 11), and the application layer 15 is formed. The coating layer 15 thus formed is relatively fragile and often breaks up finely when removed. In the indenter 10 of the present invention, when the tip 16 of the indenter 10 is pushed into the object 90 to be measured, the coating layer 15 is peeled off from the tip 110 of the indenter body 11 by the surface of the object 90 to be measured. At this time, the coating layer 15 formed from the paint is crushed while being peeled off and adheres to the object to be measured 90.

  In addition, in the coating film 15 formed from the coating material, it is preferable that a film thickness is several micrometers (for example, 1-10) micrometer. When the coating layer 15 is 1 μm or less, a coating film 15 having a defect (pinhole or the like) tends to be formed. On the other hand, when the coating layer 15 is 10 μm or more, the coating film 15 is not easily broken finely when it is peeled off, so that the boundary between the invaded portion 12 and the non-invaded portion tends to be unclear.

Next, the coating layer 15 ′ (FIG. 9) using a non-solvent coating agent will be described.
Non-solvent coating agents suitable for the present invention include semi-solid materials. In this specification, “semi-solid material” means a wax-like material (for example, lipstick, lipstick, concealer, foundation, eyebrow, etc.) mainly composed of dental paraffin wax (JIS T6502) and oily components (liquid paraffin, etc.). ).

  The composition of the semi-solid material does not change before and after application. That is, the semi-solid material forms the coating layer 15 ′ in a semi-solid state. Therefore, the formed coating layer 15 ′ is deformed without being crushed when removed. In the indenter 10 ′ of the present invention, when the tip 16 ′ of the indenter 10 ′ is pushed into the measurement object 90, the coating layer 15 ′ is peeled off from the tip 110 of the indenter body 11 by the surface of the measurement object 90. At this time, the coating layer 15 ′ formed from the semi-solid material is deformed while being peeled off, and accumulates between the tip 110 and the surface of the measurement object 90. Depending on the viscosity and hardness of the semi-solid material, the peeled coating layer 15 ′ may adhere to the surface of the object to be measured 90, or may remain in the indenter body 11 while maintaining its accumulated shape. Further, a part of the stripped coating layer 15 ′ may adhere to the surface of the measurement object 90 and the remaining part may remain on the indenter body 11. In any case, since the coating layer 15 ′ formed in the invaginated portion 12 is removed and the coating layer 15 ′ formed in the non-invaded portion remains, the boundary between the invaded portion 12 and the non-invaded portion. Is clearly observable.

  Note that the coating film 15 ′ formed from a semi-solid material preferably has a thickness of about 10 to 20 μm. When the coating layer 15 ′ is 10 μm or less, a coating film 15 ′ having a defect (pinhole or the like) tends to be formed. On the other hand, if the coating layer 15 ′ is 20 μm or more, the amount of the coating film 15 ′ to be peeled off increases so much that when the indenter 10 ′ is separated from the object to be measured 90, it may be reattached to the indented portion 12. This is not desirable. If the coating layer 15 ′ is reattached to the invaded portion 12, the boundary between the invaded portion 12 and the non-invaded portion becomes unclear, and the measurement accuracy of the length L of the invaded portion 12 (as a result, (Measurement accuracy of hardness) may be reduced.

  When the semi-solid material is applied to the tip portion 110 of the indenter body 11, the tip portion 110 is immersed in the semi-solid material (or the tip portion 110 is inserted into the semi-solid material) rather than being applied with a brush or the like. Is simple. When the coating layer 15 ′ is formed by the method of inserting the tip portion 110, not only the semi-solid material can be attached to the tip portion 110 in an appropriate amount, but also the surface of the coating layer 15 ′ is moderately roughened to reduce the reflectance. (As will be described later, when a transparent or translucent semi-solid material is used, the reflectance of the surface of the coating layer 15 ′ is preferably low).

Here, “appropriate amount” means that when the tip of the indenter body 11 is covered with the coating layer 15 ′, the surface of the indenter body 11 is not exposed, and when the coating layer 15 ′ disappears from the indented portion 12, The amount of the coating layer 15 ′ does not remain in the invaginated portion 12.
In other words, the semi-solid material suitable for use in the present invention is that an appropriate amount adheres to the tip 110 when the tip 110 is inserted, and the surface formed when the tip 110 is attached remains rough. It has a viscosity and a hardness that can be maintained (that is, not smoothed).

  The advantage of forming the coating layer 15 ′ from a semi-solid material is that it is easy to form the coating layer 15 ′ at the tip portion 110 of the indenter body 11, and the coating layer 15 ′ is removed from the tip portion 110. Is easy.

  According to the first advantage of the semi-solid material, instead of preparing the indenter 10 'with the coating layer 15' formed in advance, the indenter body 11 and the semi-solid material are prepared and immediately before the hardness measurement. If the indenter body 11 is inserted into a semi-solid material, it can be used immediately as an indenter 10 'for hardness measurement. Therefore, since the time and the moving distance from the preparation of the indenter 10 ′ to the actual measurement can be shortened, the coating layer 15 ′ is less likely to peel before the hardness measurement and cannot be used for the hardness measurement ( Inferior indenter 10 'is less likely to occur.

  According to the second advantage of the semi-solid material, the coating layer 15 ′ remaining on the tip 110 of the indenter body 10 ′ can be easily removed after the indenter 10 ′ is used for hardness measurement. It is extremely easy to reproduce as. As an example, when hardness measurement is performed a plurality of times on the same measured object, only one indenter body 110 is prepared, and “formation of coating layer 15 ′”, “hardness measurement”, “coating” The operation of “removing the layer 15 ′” can be repeated a plurality of times. Therefore, since the number of indenter main bodies 110 required can be reduced, the cost for the indenter 10 'can be suppressed.

  Among the semi-solid materials for forming the coating layer 15 ', dental paraffin wax and wax-like materials for lips (lipstick, lipstick) have been confirmed to be safe in the mouth. It is suitable as a coating agent 15 ′ for the indenter 10 used for hardness measurement.

Moreover, it is preferable to make the color and transparency of the coating film 15 and the indenter body 11 different so that the coating film 15 and the indented portion 12 (the indenter body 11 is exposed) can be visually distinguished.
As an example, as described above, the indenter body 11 is formed from a transparent material (for example, sapphire or diamond), and the coating layer 15 is formed from an opaque coating agent. As another example, if the indenter body 11 is formed of an opaque and dark material (for example, cemented carbide), the coating layer 15 is formed of a coating agent having high brightness. As described above, when the color and the transparency are different, it is very easy to distinguish the indented portion 12 (the indenter body 11 is exposed) from the coating layer 15 when observed with a microscope. The length L can be measured with high accuracy.

  An example of the coating agent suitable for forming the opaque coating layer 15 is an opaque paint. Specifically, paints containing organic pigments and paints containing inorganic pigments can be used, and it is desirable to select them in consideration of compatibility with the indenter body 11.

In the case of a paint containing an inorganic pigment, the inorganic pigment preferably contains a compound containing at least one element selected from the group consisting of zinc, titanium, lead and calcium. Examples of inorganic pigments containing compounds of zinc, titanium, lead and calcium include zinc white (zinc oxide), zinc sulfide (ZnS), lithopone (mixed pigment of ZnS and BaSO ₄ ), titanium dioxide (TiO ₂ ), lead white (2PbCO ₃ Pb (OH) ₂ ), calcium carbonate (CaCO ₃ ), calcium hydroxide (Ca (OH) ₂ ) and the like. These inorganic pigments are known as white pigments with high hiding power. Therefore, when these inorganic pigments are applied to the indenter body 11 made of a transparent material, the contrast between the indented portion 12 and the coating layer 15 becomes clearer, and the length L of the indented portion 12 (the indentation depth). D) can be measured with high accuracy.

  Further, as a coating agent suitable for forming the opaque coating layer 15, an opaque semi-solid material is also suitable. Specific examples include lipstick, concealer, eyebrow and the like.

  In addition, when it is difficult to distinguish the coating layer 15 and the invaded portion 12 by color and transparency (for example, when the color and transparency of the coating layer 15 and the invading portion 12 are the same or similar, Even if it is transparent or translucent, the boundary between the coating layer 15 and the recessed portion 12 can be clearly recognized if the reflectance of the coated layer 15 and the recessed portion 12 is different. Therefore, the length L of the invaded portion 12 can be measured with sufficiently high accuracy by making the reflectance of the coating layer 15 and the invading portion 12 different.

  As an example in which the reflectances of the coating layer 15 and the indenter body 11 are different, there is a method of forming the coating layer 15 having a low reflectance. Since the tip portion 110 of the indenter body 11 is mirror-finished, the reflectance is high. Therefore, when the reflectance of the coating layer 15 is lowered (for example, the coating layer 15 having an uneven surface, the matte coating layer 15 or the like), the indented portion 12 (the indenter main body 11 is removed) when observed with a microscope. It is easy to distinguish between the exposure and high reflectance) and the coating layer 15 (low reflectance).

Next, two types of hardness measurement systems using the indenter of the present invention will be described. One is a handy type hardness measurement system (FIGS. 10 to 14), and the other is an installation type hardness measurement system (FIG. 15).
In the hardness measurement system described below, the indenter 10 having the coating film 15 formed from an opaque paint will be described as an example. However, instead of the indenter 10, a coating layer 15 ′ made of a semi-solid material is provided. An indenter 10 'can also be used.

  First, a handy type hardness measurement system 40 and a method of using the same will be described with reference to FIGS. In this example, the hardness of the object to be measured (the dental caries portion 94) is measured by the hardness measurement system 40.

  As shown in FIG. 10, the hardness measurement system 40 includes a pressing instrument (handpiece 41) to which the indenter 10 is fixed, a microscope 49, a computer 60 to which the microscope 49 is connected, and a display connected to the computer 60. 61.

  The handpiece 41 can be inserted into the mouth and is sized and shaped to be held by a measurer (dentist). The handpiece 41 includes a holder 411 and a pressing mechanism 412 (see FIGS. 11 and 12).

  The holder 411 is for stably holding the indenter 10 while pressing the indenter 10 against the carious portion 94. A recess for receiving the rear end 17 of the indenter 10 is formed at the front end 411a of the holder 411 (FIG. 12).

The pressing mechanism 412 is a mechanism for pressing the indenter 10 held by the holder 411 against the object to be measured (the carious portion 94) with a predetermined pressure. An example of the pressing mechanism 412 includes a coil spring 413 and a switch 414 (FIG. 12). The holder 411 is biased downward by the coil spring 413.
When the tip 16 of the indenter 10 held by the holder 411 is pressed against the carious portion 94 (in the direction of arrow A in FIG. 10), the indenter 10 receives stress in the opposite direction (in the direction of arrow B in FIG. 12). The holder 411 presses and shrinks the coil spring 413, and the rear end 411 b of the holder 411 approaches the switch 414. When the rear end 411b contacts the switch 414, the lamp 81 is turned on. The pressure applied to the indenter 10 when the lamp 81 is lit is determined by the spring constant of the coil spring 413. That is, in order to apply an arbitrary pressure (for example, 150 gf) to the indenter 10, the spring constant of the coil spring 413 is adjusted so that the rear end 411 b of the holder 411 contacts the switch 414 when the pressure is reached. Good.

  As the microscope 49, an optical microscope, a measurement microscope, or the like is suitable. The measuring microscope 49 refers to a microscope having functions such as point-to-point measurement, angle measurement, and area measurement. When the measuring microscope 49 is used, it is easy to measure the length L of the invaginated portion 12. A microscope 49 having a high magnification of 200 to 1000 times is suitable.

  FIG. 13 shows an example of the microscope 49. The microscope 49 includes a stage 491 for placing a sample (indenter 10) and a lens barrel 493 for observing the sample (indenter 10). The lens barrel 493 includes an image pickup element 493a, a lens 493b, and the like. The stage 491 can be moved in the XY direction by rotating the knob x1 for adjusting the X direction of the stage 941 and the knob y1 for adjusting the Y direction of the stage 941. Further, the Z direction of the lens barrel 493 can be moved by rotating the knob z1 that adjusts the Z direction of the lens barrel 493.

  When observing the tip 16 of the indenter 10 (specifically, the indented portion 12) at a high magnification of the microscope 49, it takes time to find the tip 16 of the indenter 10 under the microscope. Therefore, it is preferable to fix an indenter base 492 for placing the indenter 10 at a predetermined position of the stage 491 and to observe the distal end portion 16 of the indenter 10 using the indenter base 492.

Here, the “indenter 492” is an instrument as shown in FIG. 14 (a), and is a semi-cylindrical recess 492a extending sideways, and a semicircular wall surface provided vertically on one side of the recess 492a. 492b. The semi-cylindrical recess 492a can support the indenter 10 sideways (in the direction in which the long axis 13 of the indenter 10 is horizontal). The rear end 17 of the indenter 10 is brought into contact with the semicircular wall surface 492b.
If the indenter base 492 is used, the position of the tip 16 of the indenter 10 can be set at a substantially constant position (as long as the indenter 10 having the same size is used). Further, if the indenter base 492 is used, the indenter 10 can be held in a state of being lifted from the stage 491 of the microscope 49, so that the indenter 10 can be easily placed with tweezers or the like. In particular, it is preferable to provide the depression 492e in the indenter base 492 so that the central portion of the indenter 10 is separated from the indenter base 492, because the indenter 10 can be operated by gripping the central portion of the indenter 10 with tweezers.

  Further, the recess 492a can be other than a semi-cylindrical shape. For example, in the indenter base 492 'of FIG. 14B, the recess 492c has a V-shaped groove shape. When the shape of the recess 492c is changed to a V-shaped groove, the shape of the wall surface 492d changes to a triangle. Similarly to the indenter base 492 in FIG. 14A, the indenter base 492 'in FIG. 14B can hold the indenter 10 sideways and in a predetermined position.

  Normally, the position of the stage 491 of the microscope 49 (XY direction in FIG. 13) and the position of the lens barrel 493 of the microscope 49 (Z direction in FIG. 13) can be arbitrarily changed. Therefore, when observing the indenter 10 using the indenter base 492, prior to actual hardness measurement, the indenter 10 is placed on the indenter base 492 and the position where the tip 16 of the indenter 10 can be observed is examined. Then, the position of the stage 491 in the Y direction and the position of the lens barrel 493 in the Z direction are substantially fixed at these positions. Although the direction of the stage 491 is not fixed, a mark (for example, a stopper) is attached to a position where the tip 16 can be seen instead. When the indenter 10 is placed on the indenter base 492, the indenter 10 can be easily placed by moving the stage 491 in the X direction (for example, the upper left direction in the figure). After the indenter 10 is placed, the stage 491 is moved in the direction opposite to the X direction (lower right in the figure), and the stage 491 is fixed at a predetermined position (stopper position).

  This operation makes it easy to find the tip 16 of the indenter 10 under a microscope. When the tip 16 of the indenter 10 is deviated from the center of the image or when the tip 16 of the indenter 10 is not aligned, the knobs x1, y1, and z1 are rotated so that the position of the stage 491 in the XY direction, The position of the lens barrel 493 in the Z direction can be finely adjusted.

  A microscope 49 and a display 61 are connected to the computer 60, and an image of the tip 16 of the indenter 10 observed with the microscope 49 can be displayed on the display. This image can be saved as image data. Further, a “measurement program” and a “hardness conversion program” may be installed in the computer. If the measurement program is used, the length L of the invaginated portion 12 formed at the tip 16 of the indenter 10 can be easily measured. Moreover, if the hardness conversion program is used, the hardness of the DUT 90 can be easily obtained from the numerical data of the length L obtained by the measurement program or the like.

  Next, an installation type hardness measurement system and a method of using the same will be described with reference to FIG. In this example, the hardness of the plate-shaped object 90 is measured by a hardness measurement system. The microscope 49, the computer 60, and the display 61 are the same as the handy type hardness measurement system, and thus illustration and description thereof are omitted.

  This installation type hardness measurement system uses an installation type pressing device 51 (FIG. 15) instead of the handpiece 41 used in the handy type hardness measurement system 40. That is, the installation type hardness measurement system includes a pressing device 51 (FIG. 15) and a measurement microscope 49 (FIG. 13).

  As shown in FIG. 15, the pressing device 51 includes a measurement table 52 on which the object to be measured 90 is placed, a holder 411 that holds the indenter 10, and an arm 53 that holds the holder 411.

The pressing mechanism 80 of the pressing device 51 includes an arm 53, a pressure sensor 82, and a controller 83.
The arm 53 can move the holder 411 up and down. Therefore, by operating the arm 53, the holder 411 can be lowered to apply a predetermined pressure to the indenter 10.
The pressure sensor 82 is for measuring the pressure applied to the indenter 10, and is provided in the arm 53. The pressure sensor 82 sends pressure measurement data to the controller 83.
The controller 83 turns on the lamp 81 when the measurement data received from the pressure sensor 82 reaches a preset pressure (predetermined pressure). By changing the set pressure of the controller 83, the pressure applied to the indenter 10 can be changed.

The measurer lowers the arm 53, presses the indenter 10 against the object 90 to be measured, and stops the descent of the arm 53 when the lamp 81 is lit. Thereby, the indenter 10 can be pressed against the DUT 90 with a predetermined pressure.
The operation of the arm 53 may be performed manually by the measurer, but can also be automated by computer control or the like.
For example, the arm 53 is lowered by computer control, and the indenter 10 is pressed against the object 90 to be measured. When the measurement data from the pressure sensor 82 reaches a predetermined pressure, the controller 83 turns on the lamp 81 (or instead of turning on the lamp 81) and sends a signal to the computer. The computer that has received the signal stops the lowering of the arm 53. If the operation of the arm 53 is automated, the error for each measurer can be reduced.

  This installation-type hardness measurement system has a simple structure compared to the conventional Knoop hardness tester, and can be manufactured at low cost. Moreover, since the installation location does not have to be strictly horizontal, it can be installed at the manufacturing site where the device under test 90 is manufactured, and the hardness can be measured immediately. In addition, it is possible to measure the hardness with higher accuracy than simple measurement.

After pressing the indenter 10 of the present invention against the object to be measured 90 (extracted carious portion 94), the length L of the indented portion 12 was measured.
A sapphire indenter body 11 (inner angle θ = 50 °, apex radius of curvature 0.7 mil) is prepared, and a coating layer 15 is formed by applying Posca (Mitsubishi Pencil Co., Ltd.) white ink to the tip 110. did. The thickness of the coating layer 15 was several μm. An experiment was performed using the indenter 10 thus manufactured.

  The carious tooth 94 (hardness KNH = 16 prepared as the object to be measured 90 was prepared. The indenter 10 was pressed against the carious tooth and pressurized to 150 gf. Thereafter, the indenter 10 was measured with a measuring microscope (DS-3UX-SH , Manufactured by Micro Square Co., Ltd.) at a magnification of 500. A microscopic image of the indenter 10 is shown in FIG.

  As shown in FIG. 16, the coating layer 15 and the indented portion 12 were clearly visible, and the length L of the indented portion 12 was easily measured. In FIG. 16, the length L was 44 μm.

After the indenter 10 'of the present invention was pressed against the workpiece 90 (plastic plate), the length L of the invaginated portion 12 was measured.
A sapphire indenter body 11 (inner angle θ = 50 °, apex radius of curvature 0.7 mil) was prepared, and its tip 110 was inserted into dental paraffin wax (Matsukaze Co., Ltd.) to form a coating layer 15 ′. . The thickness of the coating layer 15 ′ was about 10 μm. An experiment was performed using the indenter 10 ′ thus manufactured. The surface of the coating layer 15 ′ was rough, and it was easy to visually recognize the region where the coating layer 15 ′ was formed on the surface of the indenter body 11.

  A plastic plate (hardness KNH = 6) was prepared as the measurement object 90. The indenter 10 was pressed against a plastic plate to apply pressure up to 150 gf. Thereafter, the indenter 10 was observed at 500 times with a measurement microscope (DS-3UX-SH, manufactured by Micro Square Co., Ltd.). A microscope image of the indenter 10 is shown in FIG.

  As shown in FIG. 17, the coating layer 15 ′ and the recessed portion 12 were clearly visible, and the length L of the recessed portion 12 was easily measured. In FIG. 17, the length L was 94 μm.

  The hardness measurement system of the present invention is not limited to the measurement of the hardness of dental caries in the oral cavity in the dental field, and various materials (for example, metal materials, (Metal coating, rubber material, plastic material, plastic coating, ore, etc.)

DESCRIPTION OF SYMBOLS 10 Indenter for hardness measurement 11 Indenter main body 110 Tip part of indenter body 116 Apex of front end part 12 Indented part 13 Long axis 15 Coating layer 150 Peeled coating layer 16 Tip 17 Rear end 40 Hardness measurement system 41 Handpiece 411 Holder 412 Pressing mechanism 413 Coil spring 414 Switch 50 Hardness measurement system 51 Pressing device 52 Measurement table 53 Arm 60 Computer 61 Display 80 Pressing mechanism 81 Lamp 82 Pressure sensor 90 Object to be measured (dental dentin)
91 Surface of measured object (dental dentin surface)
D Depth of intrusion L Length of intrusion

Claims (14)

An indenter for measuring the hardness of an object to be measured,
The indenter is
An indenter body with a reduced diameter tip,
An application layer applied to the surface of the tip,
An indenter for hardness measurement, wherein when the tip is pressed against the object to be measured at the time of hardness measurement, the coating layer covering the indented portion of the tip that is invaded into the object to be measured disappears.   The indenter for hardness measurement according to claim 1, wherein the coating layer is made of an opaque paint. The paint comprises a paint containing an inorganic pigment;
The indenter for hardness measurement according to claim 2, wherein the inorganic pigment contains a compound containing at least one element selected from the group consisting of zinc, titanium, lead and calcium.   The indenter for hardness measurement according to claim 1, wherein the coating layer is made of a semi-solid material.   The indenter for hardness measurement according to claim 4, wherein the semi-solid material is a dental paraffin wax or a coating material for lips.   The indenter for hardness measurement according to any one of claims 1 to 5, wherein the indenter body is made of ore having a hardness of KNH 200 or more.   The indenter for hardness measurement according to any one of claims 1 to 5, wherein the indenter body is made of cemented carbide.   The indenter for hardness measurement according to any one of claims 1 to 7, wherein the object to be measured is a tooth. A hardness measurement method for measuring the hardness of an object to be measured using the indenter for hardness measurement according to any one of claims 1 to 8,
A pressing step of pressing the indenter against the object to be measured at a predetermined pressure, and causing the tip of the indenter body to intrude into the object to be measured;
A measuring step for measuring the length of the invaginated portion where the coating layer has disappeared;
A hardness conversion step of converting the length of the indented portion into the hardness of the object to be measured;
A hardness measurement method comprising:   The hardness measurement method according to claim 9, wherein a pressing instrument for holding the indenter and pressing the indenter with a predetermined pressure is used in the pressing step.   The hardness measurement method according to claim 10, wherein the pressing instrument is a handpiece. A hardness measurement system used in the hardness measurement method according to any one of claims 9 to 11,
A holder for holding the indenter for hardness measurement according to any one of claims 1 to 8,
A pressing mechanism for pressing the indenter held by the holder against the object to be measured with a predetermined pressure;
Measuring means for measuring the length of the indented portion of the tip of the indenter body;
A hardness measurement system comprising:   The hardness measurement system according to claim 12, wherein the holder and the pressing mechanism are provided in a handpiece. The measuring means is
A microscope capable of transmitting image data of the tip of the indenter body to a computer;
A measurement program for measuring the length of the intrusion portion from the image data and generating length data,
The hardness measurement system according to claim 12 or 13, wherein the hardness measurement system further includes a hardness conversion program for converting the length data into the hardness of the object to be measured.

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