JP6741271B2 - Material testing device and material testing method - Google Patents

Description

The present invention relates to a material testing device and a material testing method.

As a test method for measuring the mechanical properties of a material, Patent Document 1 and Patent Document 2 disclose that a test piece is held by a holder, a steel ball is pressed against the test piece, and a time until the steel ball penetrates the test piece. And a so-called small punch test method for measuring the deformation amount of the test piece is disclosed.

JP, 2014-77696, A JP, 2016-99132, A

As a test method for measuring the mechanical properties of a material, a tensile test method is known in which a tensile load is applied to both ends of a dumbbell-shaped test piece to measure the tensile strength of the test piece. However, with this tensile test method, it is necessary to process the test piece into a dumbbell shape, so if the material is only a small size, such as a material taken from a structure that has deteriorated over time or a sample after thermal analysis. Could not make a test piece.

In the small punch test method described above, since the size of the test piece is usually a thin plate having a diameter of about 5 to 10 mm, it is possible to manufacture the test piece even if the material has only a small size. .. However, in the small punch test methods of Patent Document 1 and Patent Document 2, at the time of the test, the steel balls previously arranged on the test piece are pressed against the test piece by the puncher (rod). Therefore, when the test piece is made of a material having a particularly low strength, an external force is applied to the test piece by the weight of the steel ball before the test, which may cause an error in the test result.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a material testing apparatus and a material testing method capable of suppressing a measurement error to a low strength and a low rigidity test piece. And

The material testing device according to claim 1, wherein a holder having a fixing portion to which a peripheral portion of a flat plate-shaped test piece is fixed, a contact member having a spherical surface that contacts the central portion of the test piece, and the test piece And a holding member capable of holding the abutting member in a state of being spaced apart from the spherical surface, and a drive for driving the abutting member or the holder such that the test piece is pressed by the abutting member. And a measuring unit that measures the load applied to the contact member and the displacement of the test piece.

According to the above configuration, the peripheral portion of the test piece is fixed to the fixed portion of the holder of the material testing device, and the contact member or the holder is driven by the drive unit so that the test piece is pressed by the contact member. , The central portion of the test piece is pressed by the spherical surface of the contact member to apply a load to the test piece. At this time, the mechanical characteristics of the test piece can be measured by measuring the load applied to the contact member and the displacement of the test piece by the measuring unit.

Here, for example, in the stage before the material test, the contact member can be held by the holding member in a state in which there is a space between the spherical surface and the test piece. Therefore, it is possible to prevent the spherical surface of the contact member from coming into contact with the test piece before the material test to apply an external force to the test piece, and it is possible to suppress the measurement error in the material test to be small. The spherical surface of the contact member only needs to be a spherical surface on the side that contacts the test piece, and includes, for example, a configuration in which the tip of the contact member has a hemispherical shape.

The material testing device according to claim 2 is the material testing device according to claim 1, wherein the drive unit drives the contact member vertically upward or drives the holder vertically downward. Then, the contact member is brought into contact with the lower surface of the test piece.

According to the above configuration, the contact member is brought into contact with the lower surface of the test piece by driving the contact member vertically upward or by driving the holder vertically downward by the drive unit. Therefore, as compared with the structure in which the contact member is brought into contact with the upper surface of the test piece, the holding member uses gravity to hold the contact member with a space between the spherical surface and the test piece. You can

A material testing apparatus according to a third aspect is the material testing apparatus according to the first or second aspect, wherein the abutting member is a steel ball.

According to the above configuration, since the contact member is a steel ball, the contact surface is spherical regardless of which surface of the contact member contacts the test piece. Therefore, compared to a configuration in which only the contact surface of the contact member is spherical, the spherical surface can be reliably brought into contact with the test piece, and the contact surface can be tested by simply replacing the steel ball. Appropriate materials and dimensions can be used according to the material, size, thickness, etc. of the piece.

The material testing device according to claim 4 is the rod material testing device according to claim 3, wherein the holding member has a recess for supporting the steel ball in a centered state formed on an end face on one end side in the longitudinal direction. Is.

According to the above configuration, since the recess for supporting the steel ball in the centered state is formed on the end face on the one end side in the longitudinal direction of the rod, the position of the steel ball with respect to the rod is displaced or the steel ball is dropped from the rod. Can be suppressed. The "centered state" refers to a state in which the center of the steel ball is located on the central axis of the rod.

The material testing device according to claim 5 is the material testing device according to any one of claims 1 to 4, wherein the holder is configured to perform the test between the fixing portions that are respectively formed on surfaces facing each other. A first holder and a second holder that sandwich the piece are provided, and at least one of the fixed portion of the first holder and the fixed portion of the second holder is formed with a protrusion protruding from the facing surface. ing.

According to the above configuration, the protrusion is formed on at least one of the fixed surface of the first holder and the fixed surface of the second holder that holds the test piece. Therefore, by holding the test piece by the projection, for example, by making the projection bite into the test piece, it is possible to prevent the test piece from coming off the holder.

The material testing apparatus according to claim 1 further includes a housing that accommodates the holder, and the holder is rotatably held in the housing via a bearing.

According to the above configuration, the holder is rotatably held in the housing via the bearing. Therefore, when a torsional moment is generated in the holder, for example, when the holder is housed in the housing or when the test piece is pressed by the contact member, the holder to which the test piece is fixed rotates together with the test piece with respect to the housing. To do. Therefore, it is possible to prevent the torsional moment from acting on the test piece.

In the material testing method according to claim 6 , a plate-shaped test piece is prepared from a material collected from a structure or a sample after thermal analysis, and a peripheral edge of the test piece is fixed to a fixed portion of a holder rotatably supported by a bearing. The contact member having a spherical surface and having a spherical surface and being held in a state where there is an interval between the spherical surface and the test piece, is driven in a direction of pressing the test piece, By applying a load to the test piece by pressing the central portion of the test piece by the spherical surface of, by measuring the load applied to the contact member and the displacement of the test piece, the mechanical properties of the test piece taking measurement.

According to the above configuration, in the stage before driving, the contact member is held in a state in which there is a space between the spherical surface and the test piece. Therefore, it is possible to suppress the external force from being applied to the test piece due to the contact of the spherical surface of the contact member with the test piece before the material test. The characteristics can be measured accurately.

As described above in detail, according to the present invention, the measurement error can be suppressed to be small even for a test piece having low strength and low rigidity.

It is a block diagram which shows the principal part of the material testing apparatus which concerns on 1st Embodiment of this invention. (A) is an exploded cross-sectional view showing a holder, an abutting member, and a holding member of the material testing device according to the first embodiment of the present invention, and (B) is seen from the AA line direction of (A). It is a top view. (A) is a cross-sectional view showing a state before the test of the material testing apparatus, (B) is a cross-sectional view showing a state in which a contact member of the material testing apparatus is brought into contact with a test piece, and (C) is a sectional view. It is sectional drawing which shows the state which is pressing the test piece by the contact member of a material testing device. It is sectional drawing equivalent to FIG.3(A) which shows the material testing apparatus which concerns on 2nd Embodiment of this invention. It is a sectional view corresponding to Drawing 3 (A) showing a material testing device concerning a 3rd embodiment of the present invention. (A)-(C) is a graph which shows the relationship between the load added to a test piece and the displacement of a test piece.

(First embodiment)
Hereinafter, the material testing apparatus and the material testing method according to the first embodiment of the present invention will be described with reference to FIGS. 1 to 3.

<Structure>
As shown in FIG. 1, the material testing apparatus 10 of the present embodiment includes a metal holder 16 made up of a first holder 12 and a second holder 14 arranged side by side in the vertical direction, and a metal holder 16 for accommodating the holder 16. Housing 18 of.

The first holder 12 has a cylindrical shape having a through hole 20 formed along the vertical direction at the center, and the outer diameter of the upper portion of the first holder 12 in the vertical direction is smaller than the outer diameter of the lower portion of the vertical direction. The reduced diameter portion 12A. Similarly, the second holder 14 has a cylindrical shape having a through hole 22 formed along the vertical direction at the center, and the lower end of the second holder 14 in the vertical direction has an outer diameter of the upper end in the vertical direction. The reduced diameter portion 14A is smaller than the outer diameter.

The housing 18 includes an upper housing 28 and a lower housing 30 that are arranged side by side in the vertical direction, and the upper housing 28 and the lower housing 30 accommodate a recess 28A that accommodates the first holder 12 and the second holder 14, respectively. , 30A. Further, the female screw portion 28B formed on the upper housing 28 and the male screw portion 30B formed on the lower housing 30 are screwed together, so that the upper housing 28 and the lower housing 30 are fixed.

Bearings 24 and 26 are fitted to the outer peripheral surface of the reduced diameter portion 12A of the first holder 12 and the outer peripheral surface of the reduced diameter portion 14A of the second holder 14, respectively. The first holder 12 is housed in the recess 28A of the upper housing 28 and the second holder 14 is housed in the recess 30A of the lower housing 30 via the bearings 24 and 26 so as to be rotatable about the central axis P of the holder 16. ing.

The facing surface 12B (vertical direction lower end surface) of the first holder 12 facing the second holder 14 and the facing surface 14B (vertical direction upper end surface) of the second holder 14 facing the first holder 12 are horizontal to each other. It is extended. Further, the peripheral portions of the openings 20A and 22A of the through holes 20 and 22 in the facing surfaces 12B and 14B are fixed portions 32 and 34, respectively.

Further, as shown in FIG. 2A, a plurality of (three in the present embodiment) protrusions 36 protruding from the facing surfaces 12B and 14B of the first holder 12 and the second holder 14 are provided on the fixing portions 32 and 34. , 38 are formed respectively.

As shown in FIG. 2B, the protrusions 36 and 38 are formed over the entire circumference along the peripheral edges of the openings 20A and 22A of the through holes 20 and 22. Further, as shown in FIG. 2A, the protrusions 36 and 38 have a right triangle shape in a cross section along the central axis P direction of the holder 16.

Specifically, the protrusions 36, 38 are inclined faces 36A, 38A that are inclined outwardly in the radial direction of the holder 16 from the facing faces 12B, 14B of the first holder 12 and the second holder 14 toward the apex of the protrusions 36, 38. And the orthogonal surfaces 36B and 38B extending in the vertical direction from the facing surfaces 12B and 14B of the first holder 12 and the second holder 14 toward the vertices of the protrusions 36 and 38.

By screwing the upper housing 28 and the lower housing 30, as shown in FIGS. 1 and 2A, a test is performed between the fixing portion 32 of the first holder 12 and the fixing portion 34 of the second holder 14. The peripheral portion of the piece S is clamped. As will be described later, the test piece S is made of a resin material such as urethane, which is softer than a metal material, as an example, and is processed into a circular flat plate shape.

In addition, in the through hole 22 of the second holder 14, a rod 40 as an example of a holding member and an example of an abutting member placed on the vertical upper end face (end face at one end in the longitudinal direction) of the rod 40 are provided. Steel balls 42 and are inserted.

The rod 40 is a metal columnar member having an outer diameter smaller than the inner diameter of the through hole 22, and is arranged such that its central axis overlaps with the central axis P of the holder 16. Further, a recess 44 is formed on the upper end surface in the vertical direction of the rod 40, and the inner peripheral surface 44A of the recess 44 approaches the central axis of the rod 40 toward the lower end side in the vertical direction (the other end side in the longitudinal direction). Is a linearly inclined inclined surface (conical surface).

The steel ball 42 has a diameter smaller than the inner diameter of the through hole 22 and a diameter larger than the outer diameter of the rod 40, and the vertically lower portion is fitted into the recess 44 of the rod 40. The steel ball 42 moves along the inner peripheral surface 44A of the recessed portion 44 of the rod 40, so that the steel ball 42 is held in a centered state, that is, in a state where the center is located on the central axis of the rod 40. Further, the steel ball 42 is held on the upper end surface of the rod 40 in the vertical direction with a space provided between the steel ball 42 and the test piece S.

As shown in FIG. 1, a drive unit 46 is connected to the lower end of the rod 40 in the vertical direction. The drive unit 46 is, for example, a hydraulic cylinder including a pump, a cylinder, and the like (not shown), and applies pressure to the hydraulic oil by the pump to send the hydraulic oil into the cylinder, thereby hydraulically moving the rod 40 vertically upward, that is, a test piece Drive S in the direction of pressing.

A load cell 48 is attached to the lower end of the rod 40 in the vertical direction. The load cell 48 measures the load (pressure) applied to the rod 40 and converts it into an electric signal. Similarly, a displacement sensor 50 is provided at the upper end of the rod 40 in the vertical direction. The displacement sensor 50 is, for example, a laser displacement meter, and measures the displacement of the rod 40 by a laser and converts it into an electric signal.

The load cell 48 and the displacement sensor 50 constitute a measuring unit of the material testing device 10. The material testing apparatus 10 also includes a control unit 52 that controls the drive unit 46, detects and stores the electrical signals output from the load cell 48 and the displacement sensor 50, and performs data processing.

<Test method>
When the material test is performed by the material testing apparatus 10, first, the test piece S to be tested is manufactured. As the test piece S, it is possible to use the sample as it is after thermal analysis by the thermal analysis device. It is also possible to fabricate the test piece S by processing a material collected from a resin structure installed on site into, for example, a circular flat plate shape. In this embodiment, as an example, a test piece S is obtained by cutting a urethane resin material into a flat plate shape, and then punching it out into a disk shape having a diameter of 5 mm.

Next, the second holder 14 is fitted into the recess 30A of the lower housing 30 via the bearing 26, and the test piece S is placed on the facing surface 14B of the second holder 14. Then, by mounting the first holder 12 on the test piece S, the test piece S is held by the fixing portion 32 of the first holder 12 and the fixing portion 34 of the second holder 14.

After that, the upper housing 28 is fitted into the first holder 12 via the bearing 24, and the female screw portion 28B of the upper housing 28 is screwed into the male screw portion 30B of the lower housing 30 so that the material shown in FIG. The test piece S is fixed to the test apparatus 10.

At this time, since the test piece S is made of urethane resin which is softer than metal, it is formed on the fixing portion 32 of the first holder 12 and the fixing portion 34 of the second holder 14 as shown in FIG. The apexes of the protruding projections 36 and 38 cut into the upper surface and the lower surface of the peripheral edge of the test piece S, respectively. It should be noted that at the stage where the test piece S is fixed to the holder 16, the steel ball 42 is held by the rod 40 connected to the drive portion 46 with a space provided between the steel ball 42 and the test piece S.

Next, the rod 40 is driven vertically upward by the drive unit 46 shown in FIG. 1 to bring the steel ball 42 into contact with the central portion of the lower surface of the test piece S, as shown in FIG. 3B. As it is, as shown in FIG. 3C, a load is applied to the test piece S by pressing the test piece S with the steel ball 42, and the test piece S is ruptured by the drive unit 46 shown in FIG. The rod 40 is further driven vertically upward.

The load applied to the rod 40 from the time the steel ball 42 abuts the test piece S until the test piece S breaks, that is, the load applied to the steel ball 42 is measured by the load cell 48 shown in FIG. That is, the mechanical characteristics of the test piece S are measured by measuring the displacement of the steel ball 42 with the displacement sensor 50 shown in FIG.

<Action and effect>
In this embodiment, since the test piece S is made of urethane resin, the test piece S is largely deformed (displaced) by a small external force as compared with the test piece made of a metal material. Further, the test piece S is easily deformed (displaced) due to a torsional moment about the central axis P of the holder 16 generated when the holder 16 is housed in the housing 18 or when the test piece S is pressed by the steel ball 42.

However, according to the present embodiment, in the stage before pressing the test piece S (the stage before the material test), the steel ball 42 is spaced apart from the test piece S fixed to the holder 16 by the rod 40. It is held in a closed state Therefore, it is possible to prevent the steel ball 42 from coming into contact with the test piece S before pressing the test piece S and applying an external force to the test piece S, and the test piece S is made of a low-strength and low-rigidity material or sample. Even in the case of being manufactured from, the measurement error of the material test can be suppressed to be small, and the mechanical characteristics of the test piece S can be accurately measured.

Further, since the holder 16 is rotatable with respect to the housing 18 around the central axis P via the bearings 24 and 26, when a torsion moment is generated in the test piece S, the test piece S together with the test piece S is generated. The holder 16 to which is fixed rotates with respect to the housing 18. Therefore, it is possible to prevent the torsion moment from acting on the test piece S.

Further, according to the present embodiment, the steel ball 42 is brought into contact with the lower surface of the test piece S by driving the rod 40 upward in the vertical direction by the drive unit 46. Therefore, as compared with the configuration in which the rod 40 is driven vertically downward to bring the steel ball 42 into contact with the upper surface of the test piece S, the rod 40 utilizes the gravity to move the steel ball 42 between the steel ball 42 and the test piece S. It can be easily held at a distance.

A recess 44 is formed on the upper end surface of the rod 40 in the vertical direction, and an inner peripheral surface 44A of the recess 44 is an inclined surface. Therefore, the steel ball 42 can be centered in the recess 44 of the rod 40 so that the center of the steel ball 42 is located on the central axis of the rod 40, and the position of the steel ball 42 with respect to the rod 40 is displaced. It is possible to prevent the steel ball 42 from dropping from the rod 40.

In this embodiment, since the steel ball 42 is used as the contact member, no matter which surface of the steel ball 42 contacts the test piece S, the contact surface is a spherical surface. Therefore, the spherical surface can be surely brought into contact with the test piece S as compared with the configuration using the contact member in which only the contact surface that comes into contact with the test piece S is spherical, and the accuracy of the material test is improved. Can be increased. Further, only by exchanging the steel balls 42, the contact surface can be made of an appropriate material and size according to the material, size, thickness, etc. of the test piece S.

Further, according to the present embodiment, the protrusions 36 and 38 are formed on the fixing portion 32 of the first holder 12 and the fixing portion 34 of the second holder 14, respectively, and the vertices of the protrusions 36 and 38 bite into the test piece S. By doing so, the test piece S is fixed to the fixing portions 32 and 24.

For this reason, when the test piece S is made from a material of a small size that is sampled on site, or when the test piece S is made from a sample that has been processed into a small size so as to fit into a thermal analysis device, the diameter of the test piece S is Even if it is small, by holding the peripheral portion of the test piece S by the protrusions 36 and 38, it is possible to prevent the test piece S from coming off the holder 16 during the material test.

Further, the protrusions 36, 38 are formed in a right triangle shape having inclined surfaces 36A, 38A inclined outward in the radial direction of the holder 16 and orthogonal surfaces 36B, 38B extending in the vertical direction. Therefore, when the test piece S placed on the projections 36, 38 is pressed by the steel ball 42, the deviation of the test piece S in the radial direction is suppressed by the orthogonal surfaces 36B, 38B of the projections 36, 38. Even if the test piece S is made of a small material or sample, the mechanical characteristics of the test piece S can be accurately measured.

(Second embodiment)
Next, a material testing device and a material testing method according to the second embodiment of the present invention will be described with reference to FIG. Note that illustration and description of the same configurations as the first embodiment, such as the housing 18, the load cell 48, and the displacement sensor 50, are omitted.

<Structure>
As shown in FIG. 4, the material testing device 60 of the present embodiment includes a metal holder 66 including a first holder 62 and a second holder 64 arranged side by side in the horizontal direction. Further, the first holder 62 and the second holder 64 have a cylindrical shape having through holes 68 and 70 formed in the center along the horizontal direction.

The facing surface 62A of the first holder 62 facing the second holder 64 and the facing surface 64A of the second holder 64 facing the first holder 62 extend in the vertical direction. Further, similar to the holder 16 of the first embodiment, the peripheral portions of the through holes 68, 70 in the facing surfaces 62A, 64A are fixed portions 76, 78 having a plurality of protrusions 72, 74, respectively, The test piece S is held by the fixing portions 76 and 78.

In addition, a pin 80 as an example of an abutting member is inserted into the through hole 70 of the second holder 64. The pin 80 is a metal columnar member having an outer diameter smaller than the inner diameter of the through hole 70, and is arranged such that its central axis overlaps with the central axis P of the holder 66. Further, the end portion of the pin 80 facing the test piece S on the one end side in the longitudinal direction has a hemispherical shape, and the contact surface 80A of the pin 80 contacting the test piece S is spherical.

In addition, in the second embodiment, the drive unit 46 also serves as a holding member for the pin 80, and the drive unit 46 drives the pin 80 in the horizontal direction. The test piece S is held with a space provided therebetween.

<Test method>
When the material test is performed by the material testing device 60, the test piece S is held by the fixing portion 76 of the first holder 62 and the fixing portion 78 of the second holder 64, as in the first embodiment. In addition, when the test piece S is fixed to the holder 66, the pin 80 is held by the clamp 82 with a space between the contact surface 80A and the test piece S.

Next, the drive portion 46 drives the pin 80 to one end side in the horizontal direction (right side in FIG. 4), and the contact surface 80A of the pin 80 presses the center portion of the end surface (left end surface in FIG. 4) of the test piece S. By doing so, a load is applied to the test piece S.

Similar to the first embodiment, the load applied to the pin 80 from the time when the contact surface 80A of the pin 80 abuts the test piece S until the test piece S breaks, and the displacement of the pin 80 are not shown in the figure. By measuring with a displacement sensor, the mechanical characteristics of the test piece S are measured.

<Action and effect>
In the present embodiment, since the contact member is the columnar pin 80, the contact member is easier to handle than the configuration of the first embodiment in which the contact member is a steel ball. That is, it becomes easy to insert the abutting member into the through hole 68 of the first holder 62 or hold the abutting member with the test piece S spaced apart.

Further, according to the present embodiment, it is possible to drive the pin 80 by the drive unit 46 and hold the pin 80 with the test piece S spaced apart. Therefore, the number of parts can be reduced as compared with the configuration in which the holding member is provided separately from the drive unit 46.

(Third Embodiment)
Next, a material testing device and a material testing method according to the third embodiment of the present invention will be described with reference to FIG. Note that illustration and description of the same configurations as the housing 18, the load cell 48, the displacement sensor 50, and the like in the first and second embodiments are omitted.

<Structure>
As shown in FIG. 5, the material testing device 90 of the present embodiment includes a metal holder 96 including a first holder 92 and a second holder 94 arranged side by side in the vertical direction. The first holder 92 and the second holder 94 have a cylindrical shape having through holes 98 and 100 formed along the vertical direction in the center.

The facing surface 92A of the first holder 92 facing the second holder 94 and the facing surface 94A of the second holder 94 facing the first holder 92 extend in the horizontal direction. Further, similarly to the holders 16 and 66 of the first and second embodiments, the peripheral portions of the through holes 98 and 100 in the facing surfaces 92A and 94A have the fixing portions 106 in which the plurality of protrusions 102 and 104 are formed, respectively. , 108, and the test piece S is held by the fixed portions 106, 108.

In addition, a rod 110 as an example of a holding member is provided in the through hole 100 of the second holder 94, and an example of an abutting member held by the vertical lower end surface (the end surface at one end in the longitudinal direction) of the rod 110 is provided. A steel ball 112 made of a magnetic material is inserted.

The rod 110 is a columnar member having an outer diameter smaller than the inner diameter of the through hole 100, and is arranged so that its central axis overlaps with the central axis P of the holder 96. Further, the rod 110 is made of a material having a magnetic force such as a ferrite magnet at the lower end in the vertical direction, which is the whole or a portion in contact with the steel ball 112.

Further, a recess 114 is formed on the lower end surface in the vertical direction of the rod 110, and the inner peripheral surface 114A of the recess 114 approaches the central axis of the rod 110 toward the upper end side in the vertical direction (the other end side in the longitudinal direction). It is an inclined surface (spherical surface) that is inclined to and curved along the outer surface of the steel ball 112.

The steel ball 112 has a diameter smaller than the inner diameter of the through hole 100 and a diameter larger than the outer diameter of the rod 110, and is attracted (magnetized) to the lower end surface of the rod 110 in the vertical direction by magnetic force. At this time, the steel ball 112 has a vertically upper portion that is in contact with the rod 110 fitted in the recess 114 of the rod 110 and is centered, that is, along the inner peripheral surface 114A of the recess 114 of the rod 110. The center of the rod 110 is held on the central axis of the rod 110. Further, the steel ball 112 is held by the rod 110 in a state of being spaced apart from the test piece S.

<Test method>
When the material test is performed by the material testing device 90, the test piece S is held by the fixing portion 106 of the first holder 92 and the fixing portion 108 of the second holder 94, as in the first and second embodiments. In addition, at the stage where the test piece S is fixed to the holder 96, the steel ball 112 is held by the rod 110 in a state of being spaced from the test piece S.

Next, the rod 110 and the steel ball 112 are driven vertically downward by a driving unit (not shown), and the steel ball 112 presses the center portion of the upper surface of the test piece S to apply a load to the test piece S.

Similar to the first and second embodiments, the load applied to the rod 110 (the load applied to the steel ball 112) from the time the steel ball 112 abuts the test piece S until the test piece S breaks, and The mechanical characteristics of the test piece S are measured by measuring the displacement of the rod 110 (displacement of the steel ball 112) with a load cell and a displacement sensor (not shown).

<Action and effect>
In the present embodiment, the steel ball 112 is a magnetic body and the rod 110 is made of a material having magnetic force. Therefore, the steel ball 112 can be attracted to the vertical lower end surface of the rod 110 by magnetic force. Therefore, the rod 110 enables the steel ball 112 to be held vertically downward with a space provided between the steel ball 112 and the test piece S.

Further, according to this embodiment, the recess 114 is formed in the lower end surface in the vertical direction of the rod 110, and the inner peripheral surface 114A of the recess 114 is a curved surface. Therefore, the steel ball 112 can be centered along the inner peripheral surface 114A of the recess 114 of the rod 110 so that the center of the steel ball 112 is located on the central axis of the rod 110.

(Other embodiments)
Although one embodiment of the present invention has been described above, the present invention is not limited to the above, and various modifications may be made without departing from the scope of the invention. Further, the configurations of the first to third embodiments can be appropriately combined.

For example, in the second embodiment, the pin 80 is driven to the one end side in the horizontal direction, and in the third embodiment, the rod 110 is driven vertically downward, but like the first embodiment, the pin 80 and the rod 110 are driven. It may be configured to be driven vertically upward and pressed against the lower surface of the test piece S.

In the first to third embodiments, the first holders 12, 62, 92 and the second holders 14, 64, 94 are configured to hold both sides of the test piece S, but the test piece S is held. The method is not limited to the above embodiment, and the holders 16, 66, and 96 may hold only one surface of the test piece S.

Further, for example, in the first embodiment, the steel ball 42 is pressed against the test piece S by driving the rod 40. However, the driving unit 46 may be provided on the holder 16 side, and the driving unit 46 may drive the holder 16 holding the test piece S to press the test piece S against the steel ball 42. By driving the holder 16 side, that is, not driving the rod 40 side, the position of the steel ball 42 with respect to the rod 40 can be further suppressed and the steel ball 42 can be further prevented from dropping from the rod 40.

Further, in the first embodiment, a temperature control device (not shown) controlled by the control unit 52 and having at least one of a heating function and a cooling function is provided around the holder 16 of the material testing apparatus 10, and the test piece S is arbitrarily set. The material test may be performed while maintaining the temperature or changing the temperature of the test piece S.

Further, in the third embodiment, the steel ball 112 is attracted (magnetized) to the lower end surface of the rod 110 in the vertical direction by magnetic force. However, for example, by forming a small through hole that opens in the vertical lower end surface of the rod 110 in the rod 110 and sucking air to create a negative pressure in the through hole, the steel ball is attached to the vertical lower end surface of the rod 110. It may be configured to adsorb 112.

Further, in the first embodiment, the test piece S is made of a urethane resin softer than the metal material, but the test piece S is made of any material such as an epoxy resin or a metal material harder than the urethane resin. May be. When the test piece S is made of a hard material, the projections 36 and 38 of the holder 16 do not need to bite into the test piece S, and the projections 36 and 38 may hold the test piece S.

Further, in the first embodiment, the bearings 24 and 26 are fitted in the first holder 12 and the second holder 14, respectively, but the bearings are fitted in only one of the first holder 12 and the second holder 14. May be. Further, the first holder 12 and the second holder 14 may be directly accommodated in the upper housing 28 and the lower housing 30 without the bearings 24 and 26.

Further, in the first embodiment, the upper housing 28 and the lower housing 30 are screwed together, so that the first holder 12 and the second holder 14 housed between the upper housing 28 and the lower housing 30 are mutually separated. It was fixed.

However, for example, the first holder 12 is provided with a flange having a through hole formed therein, the second holder 14 is provided with a flange having a female threaded portion, and a bolt is inserted into the through hole and screwed into the female threaded portion. Alternatively, the first holder 12 and the second holder 14 may be fixed to each other by using the female screw portion of the second holder 14 as a through hole and screwing a nut into a bolt inserted into both through holes.

With such a configuration, when the first holder 12 and the second holder 14 are fixed, it is possible to suppress the occurrence of a twisting moment in the first holder 12 and the second holder 14. In addition, as long as it is a fixing method capable of suppressing the occurrence of a torsion moment in the first holder 12 and the second holder 14, a method of sandwiching the first holder 12 and the second holder 14 with a clip (not shown) is optional. Can be used.

Hereinafter, Examples 1 and 2 of the present invention and Comparative Example 1 will be specifically described with reference to FIG. In addition, in the following Examples 1 and 2 and Comparative Example 1, the material test of the test piece was performed using the material testing apparatus having the same configuration as the material testing apparatus 10 of the first embodiment shown in FIG.

The test piece was produced by punching a flat plate-shaped material piece made of undeteriorated urethane resin into a disk shape having a diameter of 5 mm and a thickness of 1 mm using a tool such as a cork polar. The width of the fixed portion of the first holder that holds the test piece was 0.75 mm, and the inner diameter of the through hole was 3.5 mm. The outer diameter of the rod that holds the steel ball and the inner diameter of the through hole of the second holder were set appropriately according to the diameter of the steel ball.

(Example 1)
In Example 1, the material test was performed multiple times with the diameter of the steel ball being 2.0 mm. The load applied to the test piece S is a point symmetric tension mode load in the plane of the test piece S. The load applied to the test piece measured by the load cell and the displacement of the test piece measured by the displacement sensor are shown in FIG. As can be seen from FIG. 6(A), a load displacement curve can be obtained by pressing a steel ball having a diameter of 2.0 mm against the lower surface of the test piece having a diameter of 5 mm, and the mechanical characteristics of the test piece can be obtained. ..

(Example 2)
In Example 2, the material test was performed multiple times with the diameter of the steel ball being 2.5 mm. FIG. 6B shows the load applied to the test piece measured by the load cell and the displacement of the test piece measured by the displacement sensor. As can be seen from FIG. 6B, a load displacement curve can be obtained by pressing a steel ball having a diameter of 2.5 mm against the lower surface of the test piece having a diameter of 5 mm, and the mechanical characteristics of the test piece can be obtained. ..

(Comparative Example 1)
In Comparative Example 1, the material test was performed multiple times with the diameter of the steel ball being 3.0 mm. FIG. 6C shows the load applied to the test piece measured by the load cell and the displacement of the test piece measured by the displacement sensor. In Comparative Example 1, as shown in FIG. 6C, the load displacement curve was stepwise, and the desired load displacement curve could not be obtained.

That is, the test piece pressed and deformed by the steel ball comes into contact with the inner peripheral surface of the through hole of the first holder, and a load other than the pressing force of the steel ball is applied to the test piece, so that only the influence of the steel ball The load displacement curve could not be obtained.

From Examples 1 and 2 and Comparative Example 1, when the inner diameter of the through hole of the first holder is 3.5 mm, the diameter of the test piece is 5 mm, and the thickness is 1 mm, the diameter of the steel ball should be smaller than 3.0 mm. It was confirmed that a desired load displacement curve can be obtained with.

When the diameter of the steel ball is smaller than the thickness of the test piece, the load mode becomes a fracture mode due to perforation such as when the test piece is pierced by a needle, and the tensile mode disappears. That is, if the diameter of the steel ball is smaller than the thickness of the test piece, a desired load displacement curve cannot be obtained, so it is preferable to make the diameter of the steel ball larger than 1.0 mm.

10, 60, 90 Material testing device 12, 62, 92 First holder 12B, 62A, 92A Facing surface 14, 64, 94 Second holder 14B, 64A, 94A Facing surface 16, 66, 96 Holder 18 Housing 32, 34, 76, 78, 106, 108 Fixing part 36, 38, 72, 74, 102, 104 Protrusion 40, 110 Rod (an example of a holding member)
42, 112 steel ball (an example of a contact member)
44, 114 recesses 44A, 114A inner peripheral surface 46 drive unit 48 load cell (an example of a measuring unit)
50 Displacement sensor (an example of measuring unit)
80 pins (an example of contact member)
S test piece

Claims (6)

A holder having a fixing portion to which the peripheral portion of the flat plate-shaped test piece is fixed,
An abutting member having a spherical surface that abuts the central portion of the test piece,
A holding member capable of holding the abutting member in a state in which a space is provided between the test piece and the spherical surface,
A drive unit that drives the contact member or the holder so that the test piece is pressed by the contact member;
A measuring unit that measures the load applied to the contact member and the displacement of the test piece,
A housing for accommodating the holder,
Equipped with
The material testing device in which the holder is rotatably held in the housing via a bearing . The driving unit drives the contact member upward in the vertical direction or drives the holder downward in the vertical direction to bring the contact member into contact with the lower surface of the test piece. Material testing equipment. The material testing device according to claim 1, wherein the contact member is a steel ball. The holding member is a rod in which a concave portion for supporting the steel ball in a centered state is formed on the end face on the one end side in the longitudinal direction.
The material testing device according to claim 3. The holder includes a first holder and a second holder that sandwich the test piece between the fixing portions formed on the surfaces facing each other,
At least one of the fixed portion of the first holder and the fixed portion of the second holder is provided with a protrusion protruding from the facing surface.
The material testing device according to any one of claims 1 to 4. A plate-shaped test piece is prepared from the material collected from the structure or the sample after thermal analysis,
Fix the peripheral part of the test piece to the fixed part of the holder rotatably supported by the bearing,
Having a spherical surface, the abutting member held in a state in which there is a space between the spherical surface and the test piece, driven in the direction of pressing the test piece,
By applying a load to the test piece by pressing the central portion of the test piece by the spherical surface of the contact member,
By measuring the load applied to the contact member and the displacement of the test piece, to measure the mechanical properties of the test piece,
Material test method.