JP6624564B2 - Coefficient of restitution measurement and hardness measurement - Google Patents

Description

  The present invention relates to a restitution coefficient measuring device that measures a coefficient of restitution used as an index for evaluating hardness of a sample. Further, the present invention relates to a hardness measuring machine for measuring hardness of a sample.

  Conventionally, a rebound hardness test has been used to measure the hardness of a sample, particularly a metal material. In the rebound hardness test, in general, a collision body composed of an indenter made of a hard material such as diamond and an indenter support to which the indenter is fixed collides against the surface of the sample, and the collision body bounced off the sample is The hardness of the sample is measured by measuring the rebound height or the repulsion speed. Such a rebound hardness test is, for example, a Shore hardness test and a leap hardness test.

  In the Shore hardness test, which is a rebound hardness test also specified in JIS (Japanese Industrial Standards), the hammer, which is a collision object, is allowed to freely fall from a predetermined height (fall height) onto the sample and bounces off the sample. This is a hardness test method for measuring the rebound height, which is the highest point of the hammer (see Non-Patent Document 1). In the Shore hardness test, the hammer is a collision body, and the hammer includes an indenter and an indenter support to which the indenter is fixed. Shore hardness is obtained by multiplying the ratio of the rebound height to the drop height of the hammer by a predetermined proportional constant.

  In the reap hardness test, the impact body, which is the impacting body, is ejected toward the sample by a spring, and the impact speed before the impact body collides with the sample, and the impact body rebounds when it collides with and bounces off the sample This is a hardness test method for measuring speed (that is, speed after impact body impact) (see Patent Document 1). In the leap hardness test, the impact body is a collision body, and the impact body includes an indenter and an indenter support to which the indenter is fixed. In the leap hardness test, the rebound speed of the impact body with respect to the impact speed of the impact body, which is the collision body, is measured as a restitution coefficient. Leap hardness is obtained by multiplying the coefficient of restitution by a predetermined proportionality constant.

  The rebound hardness test typified by the Shore hardness test and Leap hardness test makes it easier to perform the hardness test more quickly than the indentation hardness tests such as the Rockwell hardness test and the Vickers hardness test. It has the advantage of being able to. Furthermore, the testing machine of the rebound hardness test has advantages that the structure is simple and the portability is excellent as compared with the testing machine of the indentation hardness test.

U.S. Pat.

JIS B 7727: 2000 "Shore hardness test-Verification of testing machine"

  However, the mass of the hammer used in the Shore hardness test and the mass of the impact body used in the Leap hardness test are relatively large. For example, the mass of the hammer of the D-type Shore hardness tester is 36.2 g, and the mass of the impact body of the leap hardness tester is 5.45 g. When the hardness of a small and lightweight sample is measured using such a hammer or impact body, only a hardness value lower than the original hardness value of the sample may be obtained.

  The reason for this is that the kinetic energy of the impacting body (that is, the hammer or impact body including the indenter and the indenter support) that collides with the small and lightweight sample is not only affected by plastic deformation and elastic deformation of the sample, but also by vibration of the sample. This is because the repulsion height or repulsion speed is smaller than the repulsion height or repulsion speed that should be measured. This phenomenon, that is, the phenomenon in which the repulsion height or repulsion velocity smaller than the repulsion height or repulsion velocity to be originally measured is measured as a result of the kinetic energy of the colliding body being consumed for vibration of the sample, etc. In the book, it is called "mass effect".

  If a mass effect occurs when measuring the hardness of a sample, accurate sample hardness cannot be obtained.When measuring the hardness of a sample of 4 kg or less in the Shore hardness test, a sufficiently large mass must be used. The test must be carried out with the sample firmly fixed to the dedicated steel anvil that has it. There is no dedicated anvil for the leap hardness test. Therefore, when measuring the hardness of a small and light sample in the leap hardness test, the user prepares an appropriate table having a sufficiently large mass and firmly mounts the sample using a special paste on this table. Need to be fixed to That is, in order to accurately measure hardness using a conventional rebound hardness tester, there are limitations on the size and mass of the sample to be tested.

  In the Shore hardness test, the test direction of the Shore hardness test is limited to the vertical direction because it is necessary to measure the rebound height after the hammer is freely dropped from a predetermined drop height and hits the sample. On the other hand, in the leap hardness test, an impact body is ejected toward a sample by a spring, and a restitution coefficient, which is a ratio of a repulsion speed of the impact body to a collision speed before the impact body collides with the sample, is measured. Therefore, in the leap hardness test, it is possible to measure the coefficient of restitution and the hardness based on the coefficient of restitution in a free direction.

  As in the case of a leap hardness test, if the hardness test method uses a spring to eject a collision object to measure the coefficient of restitution of the sample and uses this coefficient of restitution as an index for evaluating the hardness of the sample, the testing machine can be freely used. Hardness test can be performed in various directions. However, even in a leap hardness test, a mass effect occurs when the sample whose hardness is to be measured is small and lightweight. Therefore, there is a need for a coefficient of restitution measuring instrument and a hardness measuring instrument that can reduce the mass effect and can perform tests in free directions.

  The present invention has been made in view of the above circumstances, and provides a coefficient of restitution measuring instrument and a hardness measuring instrument capable of reducing a mass effect and performing a test in a free direction. Aim.

In order to achieve the above object, one embodiment of the present invention provides a holder for holding a spherical indenter, an injection mechanism for injecting the indenter held by the holder from the holder toward a sample, and the indenter A speed measuring unit for measuring a collision speed, which is the speed of the indenter before colliding with the sample, and a repulsion speed, which is a speed of the indenter after the indenter bounces off the sample, and the repulsion speed with respect to the collision speed A calculation unit for calculating a coefficient of restitution, which is a ratio of the holder, wherein the front end of the holder is formed of a plurality of divided portions by forming a slit extending parallel to the axis of the holder, Is an apparatus for measuring the coefficient of restitution , wherein an outer peripheral surface of the indenter is held by the plurality of divided portions .

A preferred embodiment of the present invention, the holder is characterized that you have a cylindrical shape.
According to another aspect of the present invention, a holder for holding a spherical indenter, an injection mechanism for injecting the indenter held by the holder toward the sample from the holder, and the injection mechanism before the indenter collides with the sample. A velocity measuring unit that measures a collision velocity, which is the velocity of the indenter, and a repulsion velocity, which is the velocity of the indenter after the indenter bounces off the sample, and calculates a restitution coefficient, which is a ratio of the repulsion velocity to the collision velocity. The injection mechanism comprises: an inner cylinder having a through hole; an outer cylinder having an inner peripheral surface slidably supported on the outer peripheral surface of the inner cylinder; An indenter pushing member that is movable, and an urging spring that is disposed between the outer cylinder and the indenter pushing member and that applies an urging force to the indenter pushing member that is contracted by the movement of the outer cylinder, The outer cylinder is formed on an outer surface of the indenter pushing member. And having engageable with the firing lever grooves.
In a preferred aspect of the present invention, the indenter pushing member is a striker that collides with the indenter held by the holder.
In a preferred aspect of the present invention, the indenter pushing member is a piston rod that applies air pressure to the indenter held by the holder.

In a preferred aspect of the present invention, the speed measurement unit includes a speed measurement main body having an indenter passage connected to the through hole, and a first passage sensor and a second passage sensor arranged along the indenter passage. It is characterized by having.
In a preferred aspect of the present invention, the first passage sensor and the second passage sensor are optical sensors.
In a preferred aspect of the present invention, the speed measuring unit further includes a third passage sensor, and the first passage sensor, the second passage sensor, and the third passage sensor are arranged along the indenter passage. And the arithmetic unit is configured to control the speed of the indenter passing between the first passage sensor and the second passage sensor, and the speed of the indenter passing between the second passage sensor and the third passage sensor. The acceleration of the indenter is calculated from the speed of the indenter, and the collision speed at the moment when the indenter collides with the sample and the rebound speed at the moment when the indenter bounces off the sample are calculated.
In a preferred aspect of the present invention, the first passage sensor, the second passage sensor, and the third passage sensor are optical sensors.

In a preferred aspect of the present invention, the speed measurement unit includes a speed measurement main body having an indenter passage connected to the through hole, and a first passage sensor and a second passage sensor arranged in the calculation unit. The first passage sensor is an optical sensor having a first light projecting unit and a first light receiving unit, and the second passage sensor is an optical sensor having a second light projecting unit and a second light receiving unit. The first light projecting unit irradiates light to the inside of the indenter passage via a first optical fiber, the first light receiving unit receives the light irradiated to the inside of the indenter passage via a second optical fiber, and The light projecting unit irradiates light inside the indenter passage via a third optical fiber, and the second light receiving unit receives the light irradiated inside the indenter passage via a fourth optical fiber. .
In a preferred aspect of the present invention, the speed measurement unit includes a speed measurement main body having an indenter passage connected to the through hole, and a first passage sensor arranged in the indenter passage, wherein the calculation unit includes: The first pass sensor detects the start of the indenter and the first pass sensor detects the end of the detection of the indenter, and the arithmetic unit detects the diameter of the indenter at the start of the detection and the end of the detection. The collision speed and the repulsion speed are calculated by dividing by the time between.

In a preferred aspect of the present invention, the speed measuring unit includes a speed measuring main body having an indenter passage connected to the through hole, and the speed measuring main body includes the speed measuring unit when the speed measuring unit contacts the sample. A shutter mechanism is provided, which opens an opening of the indenter passage and closes the opening of the indenter passage when the speed measuring unit moves away from the sample.
In a preferred aspect of the present invention, the shutter mechanism includes a door disposed at an opening of the indenter passage, an opening / closing rod having a tip protruding from the speed measurement main body, and converting a movement of the opening / closing rod into an opening / closing operation of the door. And a link mechanism that performs the operation.

In a preferred aspect of the present invention, the speed measuring unit includes a speed measuring main body having an indenter passage connected to the through hole, and a front end of the speed measuring main body has a lid through hole connected to the indenter passage. A lid is fixed, and the lid through-hole has a diameter larger than 0.2 times the diameter of the indenter and smaller than the diameter of the indenter.
In a preferred aspect of the present invention, a wall surface of the lid through-hole is formed in a curved surface, and a radius of curvature of the wall surface is larger than a radius of curvature of the indenter.
In a preferred aspect of the present invention, the speed measurement main body is formed with an air vent hole extending from a side surface of the speed measurement main body to the indenter passage.
In a preferred aspect of the present invention, the indenter passage has a diameter that is at least 1.4 times the diameter of the indenter.

In a preferred aspect of the present invention, the speed measuring section includes a speed measuring main body having an indenter passage connected to the through-hole, and a connecting mechanism for connecting the outer cylinder and the holder is further provided; When moving toward the speed measuring section, the holder moves forward in the indenter passage and holds the indenter in the indenter passage.
In a preferred aspect of the present invention, the indenter is made of ceramic.
In a preferred aspect of the present invention, the indenter is a bearing ball made of alumina.
In a preferred aspect of the present invention, the diameter of the indenter is in a range of 0.5 mm to 5 mm.

Still another aspect of the present invention is a holder that holds a spherical indenter, an injection mechanism that injects the indenter held by the holder from the holder toward a sample, and a mechanism that is used before the indenter collides with the sample. A collision speed that is the speed of the indenter, and a speed measurement unit that measures a repulsion speed that is the speed of the indenter after the indenter bounces off the sample, and the sample based on a ratio of the repulsion speed to the collision speed. And a calculation unit that determines the hardness of the holder, wherein the front end of the holder is formed of a plurality of divided portions by forming a slit extending parallel to the axis of the holder, and the holder is A hardness measuring device, wherein an outer peripheral surface of an indenter is held by the plurality of divided portions .

According to the coefficient of restitution measuring device of the present invention, the collision object (object) that collides with the sample to measure the coefficient of restitution is only a spherical indenter. That is, unlike the hammer of the Shore hardness test or the impact body of the Leap hardness test, the collision body that collides with the sample does not include the indenter support to which the indenter is fixed. As a result, the mass of the collision object (object) that collides with the sample can be significantly reduced, so that the mass effect generated when measuring the coefficient of restitution is significantly reduced, and the coefficient of restitution of the sample can be accurately measured. . The spherical indenter is held by a holder, and is ejected from the holder toward the sample by an ejection mechanism. Therefore, there is no limitation on the direction in which the indenter is ejected, and the test can be performed in any direction.
Furthermore, according to the hardness measuring device of the present invention, the impact body (object) that collides with the sample to measure the hardness is only a spherical indenter. As a result, the mass of the collision body (object) that collides with the sample can be significantly reduced, so that the mass effect generated when measuring the hardness is significantly reduced, and the hardness of the sample can be accurately measured. .

It is an outline sectional view of a coefficient of restitution measuring machine concerning one embodiment of the present invention. FIG. 2A is an enlarged side view of the front end of the holder, and FIG. 2B is a cross-sectional view taken along line CC of FIG. 2A. FIG. 9 is a schematic cross-sectional view showing a state where the striker is pushed forward by the restoring force of the biasing spring when the engagement between the hook of the firing lever and the groove of the striker is released. FIG. 3 is a schematic diagram illustrating a configuration of an electric circuit of the first optical sensor. It is a schematic diagram for explaining the method of measuring the passage time from the time when the indenter passes through the first optical sensor to the time when it passes through the second optical sensor. It is the schematic which shows a mode that the indenter after measuring a coefficient of restitution is again held by a holder. FIG. 4 is a schematic cross-sectional view illustrating an example of a speed measurement main body provided with a shutter mechanism. 8A is a view taken along line D in FIG. 7, FIG. 8B is a cross-sectional view taken along line FF in FIG. 8A, and FIG. It is GG sectional drawing of b). FIG. 9A is a view taken along line E in FIG. 7, and FIG. 9B is a cross-sectional view taken along line HH in FIG. 9A. It is a schematic diagram which shows the state by which the 1st door and the 2nd door were mutually separated by the link mechanism, and the opening of the indenter passage was opened. It is a schematic diagram which shows the state by which the 1st door and the 2nd door contacted each other by the link mechanism, and the opening of the indenter passage was closed. It is the schematic which shows the speed measurement part which concerns on another embodiment. FIG. 9 is an explanatory diagram of a method of calculating a collision speed at the moment when an indenter collides with a sample and a repulsion speed at a moment when the indenter bounces off the sample. It is the schematic which shows the speed measuring part which concerns on another embodiment. It is an outline sectional view of a restitution coefficient measuring machine concerning another embodiment. FIG. 9 is a schematic cross-sectional view showing a state in which the piston rod is pushed forward by the restoring force of the biasing spring when the engagement between the hook of the firing lever and the groove of the piston rod is released. It is a top view of the reference piece used for the experiment. FIG. 18A is a graph showing a coefficient of restitution when a reference piece fixed to a steel anvil is measured by a coefficient of restitution measuring instrument, and FIG. 18B is a graph showing a reference piece fixed to a wooden anvil. It is a graph which shows the coefficient of restitution when measured with the coefficient of restitution measurement machine. FIG. 19A is a graph showing the Shore hardness when the reference piece fixed to the steel anvil is measured by a D-type Shore hardness tester, and FIG. 19B is fixed to the wooden anvil. It is a graph which shows the Shore hardness when the reference | standard piece measured by the D-type Shore hardness tester is shown. FIG. 20 (a) is a graph showing the leap hardness when the reference piece fixed to the steel anvil is measured by the leap hardness tester, and FIG. 20 (b) is the reference fixed to the wooden anvil. It is a graph which shows the leap hardness when a piece is measured with a leap hardness tester. FIG. 21A is a cross-sectional view illustrating an example of a lid fixed to the front end of the speed measurement main body, and FIG. 21B is a view taken along line I of FIG. 21A. It is a schematic diagram which shows an example of the distribution of the collision point S where an indenter collides with the surface of a sample. It is sectional drawing which shows the modification of the lid fixed to the front end of the speed measurement main body. It is sectional drawing which shows another modification of the lid fixed to the front end of the speed measurement main body.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a schematic sectional view of a restitution coefficient measuring device 1 according to one embodiment of the present invention. For convenience of description, in this specification, the direction of arrow A shown in FIG. 1 is defined as the front, and the direction of arrow B is defined as the rear.

  1 includes a holder 3 for holding a spherical indenter 2, an injection mechanism 5 for injecting the indenter 2 held by the holder 3 from the holder 3 toward a sample 8, and an indenter 2. A speed measuring unit 6 for measuring a collision speed, which is the speed of the indenter 2 before the object 8 collides with the sample 8, and a rebound speed of the indenter 2 after the indenter 2 collides with the sample 8 and rebounds; A calculation unit 7 for calculating a repulsion coefficient which is a ratio of the repulsion speed. The calculation unit 7 is disposed inside a display 10 having a display unit 10a for displaying the restitution coefficient calculated by the calculation unit 7.

  The holder 3 shown in FIG. 1 has a cylindrical shape. As shown in FIGS. 2A and 2B, the front end of the holder 3 is formed of a plurality of divided portions 3a by forming a slit 3b extending parallel to the axis of the holder 3. . In the illustrated example, the front end of the holder 3 is composed of four divided parts 3a by four slits 3b. The front end of the holder 3 may be composed of three or less divided parts 3a, or may be composed of five or more divided parts 3a. The diameter of the inner peripheral surface of the holder 3 is set to be slightly smaller than the diameter of the spherical indenter 2, and when the front end of the holder 3 is pressed against the indenter 2, the divided portion 3 a slightly extends in the outer peripheral direction of the holder 3. And the outer peripheral surface of the indenter 2 is held by the plurality of divided portions 3a.

  The shape of the holder 3 is not limited to a cylindrical shape, and may be any cylindrical shape. For example, the holder 3 may have a polygonal cylindrical shape such as a rectangular cylindrical shape or a pentagonal cylindrical shape. Even when the holder 3 has a cylindrical shape, a slit extending in parallel with the axis of the holder 3 is formed at the tip of the holder 3, and the tip of the holder 3 is composed of a plurality of divided portions. When the front end of the cylindrical holder 3 is pressed against the indenter 2, the divided portion slightly spreads outward of the holder 3, and the outer peripheral surface of the indenter 2 is held by the plurality of divided portions.

  As shown in FIG. 1, the injection mechanism 5 of the present embodiment has an inner cylinder 13 having a through hole 13a formed therein and an inner peripheral surface 12a slidably supported on an outer peripheral surface 13b of the inner cylinder 13. An outer cylinder 12, a striker 15 movable in the through-hole 13a, and a striker 15 disposed between the outer cylinder 12 and the striker 15, which contracts by the movement of the outer cylinder 12 to apply an urging force to the indenter pushing member 15. And a biasing spring 16. Further, the injection mechanism 5 shown in FIG. 1 includes a stopper 20 for restricting the movement of the striker 15 in the through hole 13a. Although not shown, the stopper 20 may be omitted. For example, if the front end of the biasing spring 16 is fixed to the striker 15, the forward movement of the striker 15 in the through hole 13a can be restricted. The wall surface of the through hole 13 a is the inner peripheral surface of the inner cylinder 13. The striker 15 constitutes an indenter pressing member that collides with the indenter 2 held by the holder 3 by the restoring force of the urging spring 16 as described later.

  The striker 15 of the present embodiment has a rod shape. More specifically, the striker 15 has a columnar striker body 15a and a columnar body support portion 15b having a diameter larger than the diameter of the striker body 15a. The striker main body 15a is fixed to the main body support 15b by burying the rear end of the striker main body 15a in the front end of the main body support 15b. The center axis of the striker body 15a coincides with the center axis of the body support 15b. Although the striker main body 15a of the present embodiment is formed of a separate member from the main body supporting portion 15b, the striker main body 15a and the main body supporting portion 15b may be formed integrally. For example, the striker body 15a can be formed on the striker 15 by performing a grinding process on a columnar member.

  The front end of the biasing spring 16 is inserted into a guide hole 15c formed in the main body support 15b. The guide hole 15c extends from the rear end to the front end of the main body support portion 15b, and the central axis of the guide hole 15c matches the central axis of the main body support portion 15b. A plug 18 for closing the opening of the outer cylinder 12 is fixed to the rear end of the outer cylinder 12, and the rear end of the biasing spring 16 is supported by the plug 18. The plug 18 of the present embodiment has a cylindrical shape, and a screw is formed on the outer peripheral surface of the plug 18. The opening formed at the rear end of the outer cylinder 12 is configured as a screw hole into which a screw formed in the plug 18 is screwed. By engaging the screw of the plug 18 with the screw hole, the plug 18 is It is fixed to the outer cylinder 12. By rotating the plug 18, the plug 18 can be moved forward or backward with respect to the outer cylinder 12. As a result, the length of the biasing spring 16 can be easily changed, so that the biasing force applied to the striker 15 by the biasing spring 16 can be easily changed.

  With such a configuration, the biasing spring 16 is disposed between the outer cylinder 12 and the striker 15. The urging spring 16 is contracted by the movement of the outer cylinder 12 and can apply an urging force to the striker 15. The contracting operation of the biasing spring 16 will be described later. As shown in FIG. 1, when the urging spring 16 is in a contracted state, the urging spring 16 applies an urging force to move the striker 15 toward the front of the injection mechanism 5 to the striker 15. . The position of the striker 15 is the firing position of the striker 15.

  An annular groove 15 d extending along the circumferential direction of the striker 15 is formed on the outer surface of the main body supporting portion 15 b of the striker 15. The groove 15d may be formed in a part of the outer surface of the main body supporting portion 15b of the striker 15. When the striker 15 is in the firing position shown in FIG. 1, the firing lever 14 having the hook 14a engageable with the groove 15d is fixed to the outer surface of the outer cylinder 11. The firing lever 14 has a through hole, into which a rotating shaft 17 fixed to a bracket (not shown) extending radially outward from the outer surface of the outer cylinder 11 is inserted. Therefore, the firing lever 14 is fixed to the outer cylinder 12 so as to be rotatable about the rotary shaft 17. As shown in FIG. 1, the outer cylinder 12 is formed with a through hole 12 b penetrating the side surface of the outer cylinder 12, and the inner cylinder 13 penetrates the side surface of the inner cylinder 13, A first long hole 13e extending along the longitudinal direction of the first hole 13 is formed. The hook 14a of the firing lever 14 passes through the through-hole 12b of the outer cylinder 12 and the first elongated hole 13e of the inner cylinder 13, and engages with the groove 15d of the striker 15.

  FIG. 3 is a schematic diagram illustrating a state in which the striker 15 is pushed forward of the injection mechanism 5 by the restoring force of the biasing spring 16 when the engagement between the hook 14a of the firing lever 14 and the groove 15d of the striker 15 is released. It is sectional drawing. As shown in FIG. 3, the striker 15 pushed forward of the injection mechanism 5 collides with a cylindrical stopper 20 fixed to the inner peripheral surface of the inner cylinder 13, thereby moving the striker 15. Is limited. More specifically, when the front end of the main body supporting portion 15b of the striker 15 collides with the rear end of the stopper 20, the forward movement of the striker 15 is restricted. While the striker 15 moves from the firing position shown in FIG. 1 to a collision position where it strikes the stopper 20 shown in FIG. 3, the front end of the striker body 15a collides with the indenter 2 held at the front end of the holder 3, Only the indenter 2 is ejected from the holder 3 toward the sample 8. As shown in FIG. 3, when the striker 15 is fired in front of the firing mechanism 5, the hook 14 a of the firing lever 14 includes a through hole 12 b formed in a side surface of the outer cylinder 12 and a side surface of the inner cylinder 13. Is in contact with the outer surface of the striker 15 through the first elongated hole 13e formed at the bottom.

  As described above, the length of the urging spring 16 can be adjusted by moving the plug 18 supporting the rear end of the urging spring 16 forward or backward with respect to the outer cylinder 12. Therefore, since the biasing force applied by the biasing spring 16 to the striker 15 can be adjusted, the collision speed of the indenter 2 ejected by the collision of the striker 15 can be adjusted. When comparing the restitution coefficients of different samples, it is preferable that the material of the indenter 2 and the collision speed of the indenter 2 are constant. In the restitution coefficient measuring device 1 of the present embodiment, the collision speed of the indenter 2 can be easily adjusted.

  Although the striker 15 of the above-described embodiment has a rod shape, the shape of the striker 15 is not limited to the rod shape. The shape of the striker 15 is arbitrary as long as it can collide with the indenter 2 held by the holder 3 and eject the indenter 2 from the holder 3 toward the sample 8.

  At the front end of the injection mechanism 5, more specifically, at the front end of the inner cylinder 13, the collision speed, which is the speed of the indenter 2 before the indenter 2 ejected by the striker 15 collides with the sample 8, and the indenter 2 A speed measuring unit 6 for measuring the repulsion speed of the indenter 2 after it collides with and bounces off is fixed. The speed measuring unit 6 of the present embodiment is attached to the front end of the inner cylinder 13 and has a speed measuring body 23 having an indenter passage 23a through which the indenter 2 passes, and a first passage sensor arranged along the indenter passage 23a. 24 and a second passage sensor 25. The indenter passage 23a is connected to the through hole 13a of the inner cylinder 13. The first passage sensor 24 and the second passage sensor 25 are arranged along the indenter passage 23a, and the first passage sensor 24 is located ahead of the speed measurement main body 23 with respect to the second passage sensor 25. “Passing sensor” is a general term for sensors that can detect the passage of an object. The passage sensor includes, for example, an optical sensor or a magnetic sensor.

  The first passage sensor 24 according to the present embodiment includes a first light projecting unit 24a that irradiates light into the indenter passage 23a, and a first light receiving unit 24b that receives light irradiated from the first light projecting unit 24a. It is. The second passage sensor 25 of the present embodiment includes a second light projecting unit 25a that irradiates light into the indenter passage 23a, and a second light receiving unit 25b that receives light irradiated from the second light projecting unit 25a. It is. Hereinafter, an embodiment in which the first passage sensor 24 and the second passage sensor 25 are optical sensors will be described.

  A light emitting diode (LED) is used for the first light projecting unit 24a and the second light projecting unit 25a of the present embodiment, and a photodiode is used for the first light receiving unit 24b and the second light receiving unit 25b. . Light from the first light projecting portion 24a is irradiated into the indenter passage 23a through a light projecting slit (not shown) arranged on the wall surface of the indenter passage 23a, and the first light receiving portion 24b is applied to the wall surface of the indenter passage 23a. It receives light passing through a light receiving slit (not shown) arranged. Similarly, the light from the second light projecting portion 25a is irradiated into the indenter passage 23a through a light projecting slit (not shown) arranged on the wall surface of the indenter passage 23a, and the second light receiving portion 25b is moved to the indenter passage 23a. Receives light that has passed through a light receiving slit (not shown) arranged on the wall surface. In the present embodiment, the first light emitting portion 24a and the first light receiving portion 24b of the first optical sensor 24 are arranged at a position 10 mm from the front end of the speed measurement main body 23, and the second light emitting portion 25a of the second optical sensor 25 is arranged. The portion 25a and the second light receiving portion 25b are arranged at a position 20 mm from the front end of the speed measurement main body 23.

  In the first optical sensor 24, the first light receiving unit 24b detects that the light emitted from the first light projecting unit 24a is blocked by the passage of the indenter 2, whereby the indenter 2 controls the first optical sensor 24. Detect that it has passed. Similarly, in the second optical sensor 25, the second light receiving unit 25b detects that the light emitted from the second light projecting unit 25a is blocked by the passage of the indenter 2, and thereby the indenter 2 emits the second light. It detects that it has passed the sensor 25. The calculation unit 7 measures a transit time from when the indenter 2 passes through the first optical sensor 24 to when it passes through the second optical sensor 25. The distance between the first optical sensor 24 and the second optical sensor 25 is determined in advance (10 mm in the present embodiment). Therefore, the calculation unit 7 determines the transit time between the time when the indenter 2 passes through the second optical sensor 25 and the time when the indenter 2 passes through the first optical sensor 24 and the time between the first optical sensor 24 and the second optical sensor 25. The collision speed of the indenter 2 can be calculated from the distance. Similarly, the calculation unit 7 calculates the time between the time when the indenter 2 passes through the first optical sensor 24 and the time when the indenter 2 passes through the second optical sensor 25 and the time between the first optical sensor 24 and the second optical sensor 25. And the repulsion speed of the indenter 2 can be calculated from the distance.

  FIG. 4 is a schematic diagram illustrating a configuration of an electric circuit of the first optical sensor 24. Hereinafter, the configuration of the electric circuit of the first optical sensor 24 will be described with reference to FIG. Since the configuration of the electric circuit of the second optical sensor 25 is the same as the configuration of the electric circuit of the first optical sensor 24, the duplicate description will be omitted.

  As shown in FIG. 4, a reverse bias potential Vr is applied to the first light receiving section 24b which is a photodiode. The first light receiving unit 24b can generate a current by receiving light from the first light emitting unit 24a that is an LED. The current generated from the first light receiving section 24b is input to the negative input terminal 30b of the first operational amplifier 30. The voltage VA is input to the positive input terminal 30a of the first operational amplifier 30. From the output terminal 30c of the first operational amplifier 30, a voltage Vopa obtained by converting the current generated from the first light receiving unit 24b by the conversion resistor 35 with reference to the voltage VA is output (current-voltage conversion).

  The voltage Vopa output from the first operational amplifier 30 is input to the negative input terminal 31b of the second operational amplifier 31 via the delay circuit 32. A predetermined base voltage Vdet is input to the positive input terminal 31a of the second operational amplifier 31. The second operational amplifier 31 outputs, from an output terminal 31c of the second operational amplifier 31, a voltage Vopb which is a difference between the voltage Vopa input to the negative input terminal 31b and the base voltage Vdet input to the positive input terminal 31a. . The voltage Vopb output from the output terminal 31c of the second operational amplifier 31 is converted into a current by the conversion resistor 36, and this current is applied to the first light emitting unit 24a.

  As shown in FIG. 4, the voltage Vopa output from the output terminal of the first operational amplifier 30 is input to the positive input terminal 38a of the comparator 38. The voltage Vcmp, which is a preset threshold, is input to the negative input terminal 38b of the comparator 38. The comparator 38 compares the voltage Vopa input to the positive input terminal 38a with the voltage Vcmp input to the negative input terminal 38b. The comparator 38 outputs the signal VS from the output terminal 38c of the comparator 38 when the voltage Vopa is higher than the voltage Vcmp. The signal VS is input to the calculation unit 7.

  According to the circuit configuration shown in FIG. 4, when the light from the first light projecting unit 24a is not blocked by the passage of the indenter 2, the voltage Vopa output from the first operational amplifier 30 is set to the preset base voltage Vdet. The light emission amount of the first light projecting unit 24a can be automatically adjusted so as to always converge. That is, the electric circuit shown in FIG. 4 operates in accordance with the output current of the first light receiving unit 24b so that the output current of the first light receiving unit 24b, which is a photodiode, becomes constant. A feedback circuit for automatically changing the light emission amount of 24a is included.

  The first light receiving unit 24b, which receives the light emitted from the first light emitting unit 24a, which is an LED, and receives the light emitted from the first light emitting unit 24a, when the light from the first light emitting unit 24a is not blocked by the passage of the indenter 2, It is preferable to always output a constant current. However, the amount of light emission of the LED differs depending on the environment in which the LED is arranged (for example, temperature and humidity). Similarly, the current output from the photodiode differs depending on the environment in which the photodiode is arranged (for example, temperature and humidity). Furthermore, since the LEDs have individual differences, when the same current is applied to different LEDs having the same structure, the light emission amounts of the LEDs are different. Similarly, since there is an individual difference between photodiodes, when different photodiodes having the same structure receive the same amount of light, the currents output by the respective photodiodes are different.

  Therefore, when the electric circuit shown in FIG. 4 is not used, the voltage Vopa output from the operational amplifier 30 varies depending on the environment in which the restitution coefficient measuring device 1 is used, and therefore, there is a possibility that an accurate restitution coefficient cannot be measured. . In order to accurately measure the coefficient of restitution, it is necessary to adjust the light emission amount of the first light projecting unit 24a and / or the output current of the first light receiving unit 24b for each measurement. Similarly, when the electric circuit shown in FIG. 4 is not used, since the voltage Vopa output from the operational amplifier 30 of the different restitution coefficient measuring device 1 is different in each restitution coefficient measuring device 1, it is possible to measure an accurate restitution coefficient. It may not be possible. In order to accurately measure the restitution coefficient, it is necessary to adjust the light emission amount of the first light projecting unit 24a and / or the output current of the first light receiving unit 24b in each restitution coefficient measuring device 1.

  When the electric circuit shown in FIG. 4 is used, the light emission amount of the first light projecting unit 24a is automatically adjusted so that the voltage Vopa output from the first operational amplifier 30 always converges on a preset base voltage Vdet. can do. Therefore, it is not necessary to adjust the light emission amount of the first light projecting unit 24a and / or the output current of the first light receiving unit 24b for each measurement. Similarly, it is not necessary to adjust the light emission amount of the first light projecting unit 24a and / or the output current of the first light receiving unit 24b in each repulsion coefficient measuring device 1. Since the configuration of the electric circuit of the second optical sensor 25 also has the same configuration as the configuration of the electric circuit of the first optical sensor 24, the same advantages can be obtained with the second optical sensor 25.

  FIG. 5 is a schematic diagram for explaining a method of measuring the passage time T1 from when the indenter 2 passes through the first optical sensor 24 to when it passes through the second optical sensor 25. That is, FIG. 5 is a schematic diagram for explaining a method of measuring the repulsion speed of the indenter 2 which has collided with the sample 8 and rebounded. The upper part of FIG. 5 shows a graph representing the output voltage Vopa of the first operational amplifier 30 of the first optical sensor 24 and the signal VS output from the comparator 38, which change with time. The lower part of FIG. 5 shows a graph representing the output voltage Vopa of the first operational amplifier 30 of the second optical sensor 25 and the signal VS output from the comparator 38, which change over time.

  The indenter 2 colliding with the sample 8 and rebounding moves to the position where the first optical sensor 24 is arranged. When the indenter 2 blocks light emitted from the first light projecting unit 24a of the first optical sensor 24 and the amount of light received by the first light receiving unit 24b decreases, the output voltage Vopa of the first operational amplifier 30 increases. As the indenter 2 passes through the first optical sensor 24, the amount by which the light emitted from the first light receiving unit 24b is blocked gradually decreases, and then gradually increases. Therefore, the amount of light received by the first light receiving unit 24b gradually decreases and then gradually increases, so that the output voltage Vopa of the first operational amplifier 30 changes to a wave SA having a convex waveform as shown in the upper part of FIG. Draw. As described above, the output voltage Vopa of the first operational amplifier 30 is input to the comparator 38 (see FIG. 4) and is compared with the threshold voltage Vcmp. When the output voltage Vopa of the first operational amplifier 30 is higher than the voltage Vcmp, the comparator 38 outputs the signal VS. When the output voltage Vopa of the first operational amplifier 30 is lower than the threshold voltage Vcmp, the comparator 38 stops outputting the signal VS. As a result, the rectangular wave RA obtained by converting the wave SA having the convex waveform by the comparator 38 is input to the arithmetic unit 7.

  The calculation unit 7 detects a time point Ta at which the signal VS is output from the comparator 38 and a time point Tb at which the output of the signal VS is stopped. That is, the time Ta is the detection start time at which the calculation unit 7 starts detecting the passage of the indenter 2 in the first optical sensor 24, and the time Tb is the time Tb when the calculation unit 7 detects the passage of the indenter 2 in the first optical sensor 24. This is the detection end point at which the detection has been completed. Further, the calculation unit 7 calculates a time point Td by dividing the time Tc from the detection of the time point Ta to the detection of the time point Tb by half. The time Tc corresponds to a time during which the calculation unit 7 detects the passage of the indenter 2 in the first optical sensor 24.

  The indenter 2 further moves to the position where the second optical sensor 25 is arranged. When the indenter 2 blocks the light emitted by the second light projecting unit 25a of the second optical sensor 25 and the amount of light received by the second light receiving unit 25b decreases, the output voltage Vopa of the first operational amplifier 30 increases. As the indenter 2 passes through the second optical sensor 25, the amount by which the light emitted from the second light receiving unit 25b is blocked gradually decreases, and then gradually increases. Therefore, the amount of light received by the second light receiving unit 25b gradually decreases and then gradually increases, so that the output voltage Vopa of the first operational amplifier 30 changes to a wave SB having a convex waveform as shown in the lower part of FIG. Draw. As described above, the output voltage Vopa of the first operational amplifier 30 is input to the comparator 38 (see FIG. 4) and is compared with the threshold voltage Vcmp. When the output voltage Vopa of the first operational amplifier 30 is higher than the voltage Vcmp, the comparator 38 outputs the signal VS. When the output voltage Vopa of the first operational amplifier 30 is lower than the voltage Vcmp, the comparator 38 stops outputting the signal VS. As a result, the rectangular wave RB obtained by converting the wave SB having the convex waveform by the comparator 38 is input to the arithmetic unit 7.

  The operation unit 7 detects a time point Te at which the signal VS is output from the comparator 38 and a time point Tf at which the output of the signal VS is stopped. That is, the time point Te is a detection start time point at which the calculation unit 7 starts detecting the passage of the indenter 2 in the second optical sensor 25, and the time point Tf is a time point at which the calculation unit 7 determines that the passage of the This is the detection end point at which the detection has been completed. Further, the calculation unit 7 calculates a time point Th obtained by dividing the time Tg from the detection of the time point Te to the detection of the time point Tf by half. The time Tg corresponds to a time during which the calculation unit 7 detects the passage of the indenter 2 in the second optical sensor 25.

  The calculation unit 7 determines the time between the time Td and the time Th as the passing time T1 from when the indenter 2 passes through the first optical sensor 24 to when it passes through the second optical sensor 25. Further, the computing unit 7 calculates the repulsion speed of the indenter 2 by dividing the distance between the first optical sensor 24 and the second optical sensor 25 by the passing time T1.

  In the present embodiment, the time between the time point Td and the time point Th is used as a passage time T1 from when the indenter 2 passes through the first optical sensor 24 to when it passes through the second optical sensor 25. When the time between the time Td and the time Th is used as the transit time T1, for example, the measurement error of the transit time T1 is made smaller than when the time between the time Ta and the time Te is used as the transit time. Is possible, and a more accurate rebound speed can be calculated.

  The collision speed of the indenter 2 is calculated by the calculation unit 7 using a similar method. That is, the calculation unit 7 determines the passage time from when the indenter 2 passes through the second optical sensor 25 to when the indenter 2 passes through the first optical sensor 24, and the calculation unit 7 calculates the collision speed. The calculation unit 7 further calculates a restitution coefficient which is a ratio of a repulsion speed to a collision speed.

  Although not shown, the calculation unit 7 may calculate the collision speed and the repulsion speed of the indenter 2 using only the first optical sensor 24 and omitting the second optical sensor 25. For example, the calculation unit 7 determines the diameter of the indenter 2 at the time Ta in FIG. The calculation unit 7 may calculate the repulsion speed of the indenter 2 by dividing by the time Tc. Similarly, the calculation unit 7 can calculate the collision speed of the indenter 2 using only the first optical sensor 24.

  As described above, when the rebound speed and the collision speed of the indenter 2 are measured using only the first optical sensor 24, the size of the speed measurement main body 23 can be reduced. Further, since the first optical sensor 24 can be arranged close to the surface of the sample 8, an accurate coefficient of restitution can be measured.

  As shown in FIG. 1, the holder 3 is inserted from the front end to the rear end of the inner cylinder 13. The outer cylinder 12 is formed with an outer cylinder flange 12c projecting radially outward of the outer cylinder 12, and the inner cylinder 13 is formed with an inner cylinder flange 13c projecting radially outward of the inner cylinder 13. Have been. A holder flange member 40 is fixed to the outer peripheral surface of the holder 3. The holder flange member 40 has a cylindrical fixing portion 40a fixed to the outer peripheral surface at the rear end of the holder 3, and a projecting flange portion 40b projecting radially outward of the holder 3 from the fixing portion 40a. The inner cylinder 13 has a second elongated hole 13d penetrating the side surface of the inner cylinder 13 and extending along the longitudinal direction of the inner cylinder 13. The protruding flange portion 40b of the holder flange member 40 is It protrudes outside the outer peripheral surface of the inner cylinder 13 through the long hole 13d.

  The coefficient of restitution measuring machine 1 has a first return spring 43 disposed between the inner cylinder flange portion 13c and the outer cylinder flange portion 12c, and the first return spring 43 attaches the inner cylinder flange portion 13c to the outer cylinder flange portion. It is urged in a direction away from the portion 12c. Furthermore, the coefficient of restitution measuring apparatus 1 has a second return spring 44 disposed between the protruding flange portion 40b and the outer cylinder flange portion 12c, and the second return spring 44 connects the protruding flange portion 40b to the outer cylinder flange portion. It is urged in a direction away from the portion 12c. A first guide rod 46 extending through a first through hole 40c formed in the protruding flange portion 40b and penetrating through the protruding flange portion 40b is fixed to the outer cylinder flange portion 12c. The first guide rod 46 extends through the inside of the second return spring 44, and the first guide rod 46 has a protruding flange portion 40 b formed by the urging force of the second return spring 44. A fastener 48 for restricting movement in a direction away from the fixing member 48 is fixed. A second guide rod 47 extending through the second through hole 40d formed in the protruding flange portion 40b and penetrating through the protruding flange portion 40b is fixed to the inner cylinder flange portion 13c.

  The outer cylinder flange portion 12c of the outer cylinder 12, the first guide rod 46, the second return spring 44, the holder flange member 40, and the fastener 48 constitute a connection mechanism 39 that connects the holder 3 to the outer cylinder 12.

  FIG. 6 is a schematic diagram showing a state where the indenter 2 after the coefficient of restitution has been measured is held by the holder 3 again. As shown in FIG. 6, in order to hold the indenter 2 on the holder 3 again, the operator forms the hook 14 a of the firing lever 14 on the outer surface of the striker 15 against the urging force of the first return spring 43. The outer cylinder 12 is pushed toward the inner cylinder 13 until it engages with the groove 15d. At this time, the holder 3 connected to the outer cylinder 12 by the connecting mechanism 39 advances in the indenter passage 23a of the speed measuring unit 6. Since the protruding flange portion 40b of the holder flange member 40 can move along the second long hole 13d formed on the side surface of the inner cylinder 12, the holder flange member 40 also moves forward of the coefficient of restitution measuring instrument 1. be able to. Since the holder flange member 40 fixed to the holder 3 is biased by the second return spring 44, the holder 3 maintains the distance between the holder 3 and the outer cylinder 12 while maintaining the repulsion coefficient. It moves toward the front of the measuring device 1. The holder 3, which moves toward the front of the coefficient of restitution measuring machine 1, advances inside the indenter passage 23a formed in the speed measuring body 23 of the speed measuring unit 6 and reaches the front end of the indenter passage 23a. 2 is held by the tip of the holder 3.

  Since the movement of the striker 15 toward the front of the coefficient of restitution measuring machine 1 is limited by the stopper 20, when the outer cylinder 12 is pushed into the inner cylinder 13, the striker 15 cannot move, while the biasing spring 16 Contracted. The hook 14a of the firing lever 14 fixed to the outer cylinder 12 moves along the first elongated hole 13e formed on the side surface of the inner cylinder 12, and engages with the groove 15d formed on the outer surface of the striker 15. When the pressing force for pushing the outer cylinder 12 toward the inner cylinder 13 is released, the outer cylinder 12 moves toward the rear of the coefficient of restitution measuring machine 1 by the urging force of the first return spring 43. At this time, the striker 15 with which the hook 14a is engaged also moves rearward, and the striker 15 waits at the firing position shown in FIG.

  When the outer cylinder 12 is pushed into the inner cylinder 13, the holder 3 is guided by the first guide rod 46. Similarly, when pushing the outer cylinder 12 into the inner cylinder 13, the holder 3 is guided by the second guide rod 47. Therefore, the rotation of the holder 3 with respect to the outer cylinder 12 and the inner cylinder 13 is prevented.

  According to such a configuration, the indenter 2 can be held by the holder 3 again by a simple operation of merely pushing the outer cylinder 12 into the inner cylinder 13. Therefore, when continuously measuring the coefficient of restitution, the burden on the operator can be reduced.

  According to the resilience coefficient measuring device 1 of the present embodiment, only the spherical indenter 2 collides with the sample 8 to measure the resilience coefficient. In other words, unlike the hammer of the Shore hardness test or the impact body of the Leap hardness test, the colliding body that collides with the sample 8 does not include the indenter support to which the indenter 2 is fixed, unlike the impact body of the shore hardness test. As a result, the mass of the collision object (object) that collides with the sample can be significantly reduced, so that the mass effect generated when measuring the coefficient of restitution is significantly reduced, and the coefficient of restitution of the sample can be accurately measured. . Further, the spherical indenter 2 is held by the holder 3, and is ejected from the holder 3 toward the sample 8 by the ejection mechanism 5. Therefore, there is no limitation on the direction in which the indenter 2 is ejected, so that the test can be performed in any direction. Furthermore, according to the coefficient of restitution measuring device 1 of the present embodiment, the collision speed of the indenter 2 can be easily adjusted by moving the plug 18 forward or backward with respect to the outer cylinder 12.

  According to the restitution coefficient measuring device 1 of the present embodiment in which the mass effect can be greatly reduced and the test can be performed in a free direction, the restitution coefficient of various samples 8 can be measured. For example, it is possible to measure not only the coefficient of restitution of a metal material but also the coefficient of restitution of food such as chocolate and bonito, or nonmetallic material such as ceramic, marble, and glass. Furthermore, only the spherical indenter 2 collides with the sample 8 and the volume of the collider is very small. Therefore, the heat capacity of the collision body is small. The time during which the indenter 2 contacts the sample 8 is instantaneous. As a result, the amount of change in the surface temperature of the sample 8 due to the test can be significantly suppressed, so that the restitution coefficient of the high-temperature or low-temperature sample 8 can be accurately measured.

  Further, in the restitution coefficient measuring machine 1 of the present embodiment, the indenters 2 having various diameters are used by appropriately selecting the size of the holder 3 and the diameter of the striker body 15a according to the diameter of the indenter 2. be able to. Therefore, since the indenter 2 having a very small diameter can be used in the restitution coefficient measuring device 1 of the present embodiment, the mass effect can be further reduced.

  From the viewpoint of reducing the mass effect generated during the test, it is preferable to use the indenter 2 having a diameter as small as possible. On the other hand, when measuring the coefficient of restitution of the sample 8 having minute irregularities on the surface, the direction of rebound of the indenter 2 from the sample 8 is greatly deviated from the direction of injection of the indenter 2 from the injection mechanism 5. (Tilting). The reason for this is that the diameter of the indenter 2 is too small for the size of the irregularities formed on the surface of the sample 8. Therefore, in order to stabilize the rebound direction of the indenter 2 while suppressing the occurrence of the mass effect, the diameter of the indenter 2 is preferably 5 mm or less.

  As the diameter of the indenter 2 decreases, the burden on the operator who measures the coefficient of restitution increases. For example, when using the indenter 2 having a very small diameter, the operator tends to lose the indenter 2. Therefore, from the viewpoint of working efficiency, the diameter of the indenter 2 is preferably 0.5 mm or more. Further, it is more preferable that the diameter of the indenter 2 be 2 mm or more in order to surely confirm the breakage and / or the breakage of the indenter 2 before measuring the coefficient of restitution. That is, the range of the diameter of the indenter 2 is preferably 0.5 mm or more and 5 mm or less, more preferably 2 mm or more and 5 mm or less.

  The speed measuring unit 6 of the restitution coefficient measuring machine 1 of the present embodiment measures the collision speed and the repulsion speed of the indenter 2 using the optical sensors 24 and 25. Therefore, the material of the indenter 2 is not limited. For example, the indenter 2 may be made of a metal material such as a cemented carbide, or may be made of a non-metallic material such as ceramic and diamond. Preferably, the indenter 2 is a bearing ball made of alumina which is a ceramic. Since the bearing ball made of alumina has high sphericity, the restitution coefficient measuring device 1 can measure an accurate restitution coefficient with high reproducibility. Bearing balls made of alumina are inexpensive and easily available on the market.

  When the speed measuring unit 6 comes into contact with the sample 8, the opening of the indenter passage 23 a of the speed measuring unit 23 is opened, and when the speed measuring unit 6 is separated from the sample 8, the speed measuring body 23 is opened. A shutter mechanism 50 for closing the opening of the 23 indenter passage 23a may be further provided. FIG. 7 is a schematic cross-sectional view showing an example of the speed measurement main body 23 provided with the shutter mechanism 50. As shown in FIG. 7, the shutter mechanism 50 of the present embodiment includes a door 51 disposed at the opening of the indenter passage 23 a, an opening / closing rod 54 whose tip projects from the speed measurement main body 23, and movement of the opening / closing rod 54. A link mechanism 55 for converting the operation into an opening and closing operation of the door 51. The speed measuring main body 23 of the present embodiment includes a first member 23b in which an indenter passage 23a is formed, in which a door 51 is arranged, and a second member 23c in which an opening / closing rod 54 is arranged.

  8A is a view taken along line D in FIG. 7, FIG. 8B is a cross-sectional view taken along line FF in FIG. 8A, and FIG. It is GG sectional drawing of b). As shown in FIG. 8A, the door 51 of the present embodiment has a first door 51a and a second door 51b that open and close the opening of the indenter passage 23a of the speed measurement main body 23 by the link mechanism 55. The link mechanism 55 will be described later. When the first door 51a and the second door 51b contact each other, the opening of the indenter passage 23a is closed, and when the first door 51a and the second door 51b are separated from each other, the opening of the indenter passage 23a is opened. FIG. 8A shows a state where the first door 51a and the second door 51b are in contact with each other and the opening of the indenter passage 23a is closed.

  As shown in FIGS. 8A and 8B, a first opening / closing guide 52 having a first circular surface 52a is fixed to a side surface of the first door 51a, and a second opening / closing guide 52 is attached to the second door 51b. A second opening / closing guide 53 having a two-arc surface 53a is fixed. The first arc surface 52a of the first opening / closing guide 52 and the second arc surface 53a of the second opening / closing guide 53 face each other. The first opening / closing guide 52 is rotatably fixed to the first member 23b via the first opening / closing shaft 56. That is, the first opening / closing guide 52 can rotate around the first opening / closing shaft 56, and as a result, the first door 51a fixed to the first opening / closing guide 52 rotates around the first opening / closing shaft 56. be able to. The second opening / closing guide 53 is rotatably fixed to the first member 23b via the second opening / closing shaft 57. That is, the second opening / closing guide 53 can rotate around the second opening / closing axis 57, and as a result, the second door 51b fixed to the second opening / closing guide 53 rotates around the second opening / closing axis 57. be able to.

  As shown in FIG. 8B and FIG. 8C, in the central region of the first door 51a, a first housing portion 51c having an arc-shaped first slope surface 51d (FIG. 8B) Reference) is formed. A second storage portion 51f having an arc-shaped second slope surface 51e is also formed in a central region of the second door 51b drawn by a virtual line (dashed line) in FIG. 8C. When the first door 51a and the second door 51b are in contact with each other, the indenter 2 can be housed in the internal space formed by the first housing 51c and the second housing 51f.

  FIG. 9A is a view taken along line E in FIG. 7, and FIG. 9B is a cross-sectional view taken along line HH in FIG. 9A. As shown in FIG. 9A, one end of an open / close spring 58 is fixed to the rear end of the open / close rod 54, and the other end of the open / close spring 58 is fixed to the second member 23c. In this state, the front end of the opening / closing bar 54 projects forward from the front end of the second member 23c. As shown in FIGS. 9A and 9B, a first protrusion 54 a and a second protrusion 54 b having a columnar shape are formed on the side surface of the opening / closing rod 54, and the first protrusion 54 a It is located ahead of the opening / closing bar 54 than the two protrusions 54b. The first protrusion 54a and the second protrusion 54b protrude from the side surface of the opening / closing rod 54 toward the first member 23b.

  The link mechanism 55 of the shutter mechanism 50 includes a first opening / closing guide 52, a second opening / closing guide 53, a first projection 54a and a second projection 54b formed on an opening / closing rod 54, and an opening / closing spring 58. FIG. 10 is a schematic diagram showing a state where the first door 51a and the second door 51b are rotated by the link mechanism 55 in a direction away from each other, and the opening of the indenter passage 23a is opened. FIG. 11 is a schematic diagram showing a state where the first door 51a and the second door 51b abut on each other by the link mechanism 55, and the opening of the indenter passage 23a is closed.

  As shown in FIG. 10, when the speed measuring body 23 of the speed measuring unit 6 is brought into contact with the surface of the sample 8, the opening / closing rod 54 is opposed to the urging force of the opening / closing spring 58, Is pushed until it is accommodated inside the speed measurement main body 23. At this time, the first projection 54a formed on the opening / closing rod 54 contacts the first arc surface 52a of the first opening / closing guide 52 and the second arc surface 53a of the second opening / closing guide 53, and the first door 51a and the first The first opening / closing guide 52 and the second opening / closing guide 53 are rotated around the first opening / closing shaft 56 and the second opening / closing shaft 57 in a direction in which the two doors 51b are separated from each other. As a result, the opening of the indenter passage 23 a of the speed measurement main body 23 is opened, and the indenter 2 can be caused to collide with the surface of the material 8.

  As shown in FIG. 11, when the speed measuring body 23 of the speed measuring unit 6 is separated from the surface of the sample 8, the opening / closing rod 54 is moved by the restoring force of the opening / closing spring 58 so that the tip of the opening / closing rod 54 measures the speed. It advances forward until it protrudes from the front end of the main body 23. At this time, the second projection 54b formed on the opening / closing bar 54 contacts the first arc surface 52a of the first opening / closing guide 53 and the second arc surface 53a of the second opening / closing guide 53, and the first door 51a and the second The first opening / closing guide 52 and the second opening / closing guide 53 are rotated around the first opening / closing axis 56 and the second opening / closing axis 57 in directions in which the two doors 51b abut on each other. As a result, the opening of the indenter passage 23a of the speed measurement main body 23 is closed, and the indenter 2 is accommodated in the internal space defined by the first accommodating portion 51c and the second accommodating portion 51f (see FIG. 8C). . At this time, the indenter 2 is guided by the first slope surface 51d formed in the first accommodation portion 51c and the second slope surface 51e formed in the second accommodation portion 51f. It is prevented from being caught between the first door 51a and the second door 51b.

  According to the shutter mechanism 50 of the present embodiment, the opening of the indenter passage 23a is opened only when the speed measurement main body 23 is brought into contact with the sample 8. On the other hand, when the speed measurement main body 23 is separated from the sample 8, the opening of the indenter passage 23a is closed. Therefore, loss of the indenter 2 ejected from the ejection mechanism 5 can be effectively prevented, and the burden on the operator can be reduced.

  FIG. 12 is a schematic diagram illustrating a speed measuring unit 6 according to another embodiment. The speed measurement unit 6 shown in FIG. 12 has a third passage sensor 26 in addition to the first passage sensor 24 and the second passage sensor 25 described above. As described above, the "passage sensor" is a generic name of a sensor that can detect the passage of an object, and the passage sensor includes, for example, an optical sensor or a magnetic sensor. Hereinafter, an embodiment in which the first passage sensor 24, the second passage sensor 25, and the third passage sensor 26 are optical sensors will be described.

  The first optical sensor 24, the second optical sensor 25, and the third optical sensor 26 are arranged along the indenter passage 23a, and the first optical sensor 24 is provided by the second optical sensor 25 and the third optical sensor 26. The second optical sensor 25 is also located ahead of the speed measuring main body 23 than the third optical sensor 26.

  The third optical sensor 26 has the same configuration as the first optical sensor 24 and the second optical sensor 25. That is, the third optical sensor 26 includes a third light projecting unit 26a that irradiates light into the indenter passage 23a, and a third light receiving unit 26b that receives light emitted from the third light projecting unit 26a. The light projecting unit 26a is an LED, and the third light receiving unit 26b is a photodiode. The configuration of the electric circuit of the third optical sensor 26 is the same as the configuration of the electric circuit of the first optical sensor 24 described with reference to FIG. That is, the light emission amount of the third light projecting unit 26a is automatically adjusted so that the voltage Vopa output from the first operational amplifier 30 provided in the electric circuit of the third optical sensor 26 always converges to the preset base voltage Vdet. It is adjusted by.

  The coefficient of restitution measuring machine 1 according to the embodiment described so far can perform a test in any direction. For example, the indenter 2 can be ejected upward or downward. If the direction in which the indenter 2 is ejected is different, gravity acts on the indenter 2 in a different direction. Therefore, a small error may occur in the measured restitution coefficient depending on the injection direction of the indenter 2. In particular, when the collision speed and the repulsion speed of the indenter 2 are low, the influence of gravity increases. Therefore, the speed of the indenter 2 at the moment when the indenter 2 collides with the surface of the sample 8 is used as the collision speed, and the speed of the indenter 2 at the moment when the indenter 2 rebounds from the surface of the sample 8 is used as the repulsion speed. Preferably, it is calculated. Hereinafter, a method of calculating the collision speed of the indenter 2 at the moment when the indenter 2 collides with the sample 8 and the repulsion speed of the indenter 2 at the moment when the indenter 2 bounces off the sample 8 will be described with reference to FIG.

  FIG. 13 is an explanatory diagram of a method of calculating the collision speed of the indenter 2 at the moment when the indenter 2 collides with the surface of the sample 8 and the repulsion speed at the moment when the indenter 2 rebounds from the sample 8. In FIG. 13, point Ps represents the surface of the sample 8, point P1 represents the position of the first optical sensor 24, point P2 represents the position of the second optical sensor 25, and point P3 represents the position of the third optical sensor 26. Represents Hereinafter, a method of calculating the collision speed of the indenter 2 at the moment when the indenter 2 reaches the point Ps after passing through the points P3, P2, and P1 in this order will be described.

  The speed of the indenter 2 passing through the point P3 (ie, the third optical sensor 26) is v3, the speed of the indenter 2 passing through the point P2 (ie, the second optical sensor 25) is v2, and the point P1 (ie, the first light). The speed of the indenter 2 passing through the sensor 24) is denoted by v1, and the speed at the moment when the indenter 2 reaches the point Ps (that is, the surface of the sample 8) is denoted by vs. Further, the average speed between the point P3 and the point P2 is v23, the average speed between the point P2 and the point P1 is v12, and the average speed between the point P3 and the point P1 is v13. The distance from point P3 to point P2 is L23, the distance from point P2 to point P1 is L12, the distance from point P3 to point P1 is L13, and the distance from point P3 to point Ps is Ls. is there. In the method described with reference to FIG. 5, the control unit 7 determines the time T23 between the time when the indenter 2 passes through the point P3 and the time when the indenter 2 passes through the point P2, and the time when the indenter 2 passes through the point P2. The time T12 before passing and the time T13 from when the indenter 2 passes through the point P3 to when it passes through the point P1 are measured.

The average speed v23 between the points P3 and P2 can be calculated from the time T23 measured by the control unit 7 and the known L23 according to the following equation (1).
v23 = L23 / T23 (1)
Similarly, the average speed v12 can be calculated by the following formula (2), and the average speed v13 can be calculated by the following formula (3).
v12 = L12 / T12 (2)
v13 = L13 / T13 (3)

Assuming that the indenter 2 is moving at a constant acceleration of the acceleration α, the relationship of the following equation (4) is established between the speed v23, the speed v2, and the speed v3.
v23 = (v2 + v3) / 2 (4)
Similarly, the relationship of the following formula (5) is established for the speed v12, the speed v1, and the speed v2, and the relationship of the following formula (6) is established for the speed v13, the speed v1, and the speed v3.
v12 = (v1 + v2) / 2 (5)
v13 = (v1 + v3) / 2 (6)
From Expressions (4), (5), and (6), the following Expressions (7), (8), and (9) are obtained.
v1 = −v23 + v12 + v13 (7)
v2 = v23 + v12-v13 (8)
v3 = v23−v12 + v13 (9)

The acceleration α of the indenter 2 can be obtained from the following equation (10).
α = (v1-v3) / T13 (10)
The calculation unit 7 obtains the speed v23, the speed v12, and the speed v13 from the above-described calculation formulas (1), (2), and (3). Therefore, the calculation unit 7 calculates the formulas (7) and (8). , And equation (9), the velocity v1, the velocity v2, and the velocity v3 can be calculated. As a result, the calculation unit 7 can calculate the acceleration α of the indenter 2 from Expression (10).

Assuming that the indenter 2 is making a constant acceleration motion at the acceleration α, the collision velocity vs of the indenter 2 at the moment when the indenter 2 collides with the point Ps (that is, the surface of the sample 8) is expressed by the following equation (11) or ( 12).
vs = (v3 ² + 2Ls · α) ^1/2 (11)
^{vs = v3 · (1 + (} (v1 / v3) 2 -1) (Ls / L13))) 1/2
... (12)
As described above, the calculation unit 7 obtains the speed v3, the speed v2, the speed v1, and the acceleration α by calculation, and the distance Ls and the distance L13 are known. Can be calculated at the moment of collision with the surface.

  Next, a method of calculating the repulsion speed at the moment when the indenter 2 bounces off the surface of the sample 8 will be described with reference to FIG. In FIG. 13, point Ps represents the surface of the sample 8, point P1 represents the position of the first optical sensor 24, point P2 represents the position of the second optical sensor 25, and point P3 represents the position of the third optical sensor 26. Represents The indenter 2 bounced off the surface of the sample 8 (that is, the point Ps) passes through the points P1, P2, and P3 in this order.

  The speed at which the indenter 2 rebounded from the point Ps passes through the point P1 (that is, the first optical sensor 24) is represented by v1 ', and the indenter 2 rebounded from the point Ps is moved to the point P2 (that is, the second optical sensor 25). The speed at which the indenter 2 bounces from the point Ps passes through the point P3 (that is, the third optical sensor 26), and the speed at which the indenter 2 bounces from the point Ps is v3 '. Further, the average speed between the points P1 and P2 is v12 ', the average speed between the points P2 and P3 is v23', and the average speed between the points P1 and P3 is v13 '. . The distance from point P1 to point P2 is L12, the distance from point P2 to point P3 is L23, the distance from point P1 to point P3 is L13, and the distance from point Ps to point P3 is Ls. is there. In the method described with reference to FIG. 5, the control unit 7 controls the time T12 ′ until the indenter 2 bounced from the point Ps passes from the point P1 to the point P2, and the indenter 2 bounced from the point Ps moves from the point P2. The time T23 'until the indenter 2 bounces from the point Ps and the time T13' until the indenter 2 bounces from the point P1 passes through the point P3 are measured.

The average speed v12 'between the points P1 and P2 can be calculated from the time T12' measured by the control unit 7 and the known L12 by the following equation (13).
v12 ′ = L12 / T12 ′ (13)
Similarly, the average speed v23 'can be calculated by the following equation (14), and the average speed v13' can be calculated by the following equation (15).
v23 ′ = L23 / T23 ′ (14)
v13 '= L13 / T13' (15)

Assuming that the indenter 2 is performing the constant acceleration motion of the acceleration α ′, the following equation (16) is established between the speed v12 ′, the speed v1 ′, and the speed v2 ′.
v12 ′ = (v1 ′ + v2 ′) / 2 (16)
Similarly, the relationship of the following expression (17) holds for the speed v23 ', the speed v2', and the speed v3 ', and the relationship of the following expression (18) holds for the speed v13', the speed v1 ', and the speed v3'. Holds.
v23 ′ = (v2 ′ + v3 ′) / 2 (17)
v13 ′ = (v1 ′ + v3 ′) / 2 (18)
From Expressions (16), (17), and (18), the following Expressions (19), (20), and (21) are obtained.
v1 ′ = − v23 ′ + v12 ′ + v13 ′ (19)
v2 '= v23' + v12'-v13 '(20)
v3 ′ = v23′−v12 ′ + v13 ′ (21)

The acceleration α ′ of the indenter 2 can be obtained from the following equation (22).
α = (v3′−v1 ′) / T13 ′ (22)
The calculation unit 7 obtains the speed v12 ′, the speed v23 ′, and the speed v13 ′ from the above-described calculation formulas (13), (14), and (15). The speed v1 ′, the speed v2 ′, and the speed v3 ′ can be calculated by (20) and Expression (21). As a result, the calculation unit 7 can calculate the acceleration α ′ of the indenter 2 rebounding from the point Ps from Expression (22).

When it is assumed that the indenter 2 is making uniform acceleration motion at the acceleration α ′, the repulsion velocity vs ′ of the indenter 2 at the moment when the indenter 2 rebounds from the point Ps (that is, the surface of the sample 8) is expressed by the following equation (23) or It can be obtained from equation (24).
vs ′ = (v1 ′ ² + 2Ls · α) ^1/2 (23)
vs ′ = v1 ′ · (1 + ((v3 ′ / v1 ′) ² −1) ·
((L13−Ls) / L13)) ^1/2 (24)
As described above, the calculation unit 7 obtains the speed v1 ′, the speed v2 ′, the speed v3 ′, and the acceleration α ′ by calculation, and the distance Ls and the distance L13 are known. It is possible to calculate the repulsion velocity vs' at the moment when 2 rebounds from the surface of the sample 8.

  As described above, the calculation unit 7 calculates the collision velocity vs of the indenter 2 at the moment when the indenter 2 collides with the sample 8 and the repulsion velocity vs ′ of the indenter 2 at the moment when the indenter 2 rebounds from the surface of the sample 8. be able to. The calculation unit 7 calculates the restitution coefficient based on the collision velocity vs of the indenter 2 at the moment when the indenter 2 collides with the sample 8 and the repulsion velocity vs ′ of the indenter 2 at the moment when the indenter 2 rebounds from the surface of the sample 8. In this case, the calculation unit 7 can obtain a coefficient of restitution in which the influence of gravity on the indenter 2 is eliminated.

  FIG. 14 is a schematic diagram showing a speed measuring unit 6 according to still another embodiment. The first light projecting unit 24a and the first light receiving unit 24b of the first optical sensor 24 of the speed measuring unit 6 and the second light projecting unit 25a and the second light receiving unit 25b of the second optical sensor 25 shown in FIG. It is arranged inside the arithmetic unit 7. That is, the first optical sensor 24 and the second optical sensor are arranged in the calculation unit 7. The speed measurement main body 23 is formed with four through holes 23d, 23e, 23f, 23g extending from the side surface of the speed measurement main body 23 to the wall surface of the indenter passage 23a. In FIG. 14, only the through holes 23d and 23f are shown, but the through hole 23e is formed at a position facing the through hole 23d, and the through hole 23g is formed at a position facing the through hole 23f. ing.

  A first optical fiber 60 extending from the first light projecting portion 24a is fitted into the through hole 23d, and light emitted from the first light projecting portion 24a is applied to the inside of the indenter passage 23a through the first optical fiber 60. Is done. A second optical fiber 61 extending from the first light receiving portion 24b is fitted into the through hole 23e, and light emitted from the first light projecting portion 24a is received by the first light receiving portion 24b through the second optical fiber 61. . That is, the first light projecting part 24a of the first optical sensor 24 irradiates the inside of the indenter passage 23a via the first optical fiber 60, and the first light receiving part 24b of the first optical sensor 24 outputs the second optical fiber 61 Through the indenter passage 23a. Similarly, a third optical fiber 62 extending from the second light projecting portion 25a is fitted in the through hole 23f, and light emitted from the second light projecting portion 25a passes through the third optical fiber 62 and passes through the indenter passage 23a. Irradiated inside. A fourth optical fiber 63 extending from the second light receiving portion 25b is fitted into the through hole 23g, and light emitted from the second light projecting portion 25a is received by the second light receiving portion 25b through the fourth optical fiber 63. . That is, the second light projecting unit 25a of the second optical sensor 25 irradiates the inside of the indenter passage 23a via the third optical fiber 62, and the second light receiving unit 25b of the second optical sensor 25 outputs the fourth optical fiber 63 Through the indenter passage 23a.

  According to the configuration shown in FIG. 14, the size of the speed measurement main body 23 can be reduced. Therefore, the speed measurement main body 23 can be inserted into a small gap. For example, as shown in FIG. 14, the coefficient of restitution of a tooth bottom 65b formed between two adjacent teeth 65a of the gear 65 can be measured.

  FIG. 15 is a schematic sectional view of a coefficient of restitution measuring machine 1 according to another embodiment. In the coefficient of restitution measuring machine 1 shown in FIG. 15, a piston rod 19 is used as an indenter pushing member instead of the striker 15 shown in FIG. The piston rod 19 applies air pressure to the indenter 2 held by the holder 3, and ejects the indenter 2 from the holder 3 toward the material 8 by the action of the air pressure. The configuration of the restitution coefficient measuring device 1 of the present embodiment other than the use of the piston rod 19 is the same as the configuration of the restitution coefficient measuring device 1 described so far, and thus the duplicate description will be omitted.

  The piston rod 19 includes a cylindrical rod body 19a, a cylindrical rod support 19b having a diameter larger than the diameter of the rod body 19a, and a disk-shaped piston head 19e fixed to the front end of the rod body 19a. And Since the rear end of the rod body 19a is embedded in the front end of the rod support 19b, the rod body 19a is fixed to the rod support 19b. The central axis of the rod main body 19a coincides with the central axis of the main body support 15b. The outer peripheral surface of the piston head 19e slides on the inner peripheral surface of the inner cylinder 13. The central axis of the piston head 19e coincides with the central axis of the rod body 19a.

  The front end of the biasing spring 16 is inserted into a guide hole 19c formed in the rod support 19b. The guide hole 19c extends from the rear end to the front end of the rod support 19b, and the center axis of the guide hole 19c matches the center axis of the rod support 19b. A plug 18 for closing the opening of the outer cylinder 12 is fixed to the rear end of the outer cylinder 12, and the rear end of the biasing spring 16 is supported by the plug 18. The plug 18 of the present embodiment has a cylindrical shape, and a screw is formed on the outer peripheral surface of the plug 18. The opening formed at the rear end of the outer cylinder 12 is configured as a screw hole into which a screw formed in the plug 18 is screwed. By engaging the screw of the plug 18 with the screw hole, the plug 18 is It is fixed to the outer cylinder 12. By rotating the plug 18, the plug 18 can be moved forward or backward with respect to the outer cylinder 12. As a result, the length of the urging spring 16 can be easily changed, so that the urging force applied by the urging spring 16 to the piston rod 19 can be easily changed.

  With such a configuration, the biasing spring 16 is disposed between the outer cylinder 12 and the piston rod 19. As described with reference to FIG. 6, the biasing spring 16 can be contracted by the movement of the outer cylinder 12 to apply a biasing force to the piston rod 19. As shown in FIG. 15, when the urging spring 16 is in a contracted state, the urging spring 16 applies an urging force to move the piston rod 19 toward the front of the injection mechanism 5 to the piston rod 19. ing. This position of the piston rod 19 is the firing position of the piston rod 19.

  An annular groove 19d is formed on the outer surface of the rod support 19b of the piston rod 19 and extends along the circumferential direction of the rod support 19b. The groove 19d may be formed in a part of the outer surface of the rod support 19b of the piston rod 19. When the piston rod 19 is at the firing position shown in FIG. 15, the firing lever 14 having the hook 14a engageable with the groove 19d is fixed to the outer surface of the outer cylinder 12. The firing lever 14 has a through hole, into which a rotating shaft 17 fixed to a bracket (not shown) extending radially outward from the outer peripheral surface of the outer cylinder 12 is inserted. Therefore, the firing lever 14 is fixed to the outer cylinder 12 so as to be rotatable about the rotary shaft 17. As shown in FIG. 15, the outer cylinder 12 has a through hole 12 c penetrating the side surface of the outer cylinder 12, and the inner cylinder 13 penetrates the side surface of the inner cylinder 13, A first long hole 13e extending along the longitudinal direction of the first hole 13 is formed. The hook 14 a of the firing lever 14 passes through the through hole 12 c of the outer cylinder 12 and the first long hole 13 e of the inner cylinder 13 and engages with the groove 19 d of the piston rod 19.

  FIG. 16 shows a state in which the piston rod 19 is pushed forward of the injection mechanism 5 by the restoring force of the biasing spring 16 when the engagement between the hook 14a of the firing lever 14 and the groove 19d of the piston rod 19 is released. FIG. As shown in FIG. 16, the piston rod 19 pushed forward of the injection mechanism 5 collides with a cylindrical stopper 20 fixed to the inner peripheral surface of the inner cylinder 13, whereby the piston rod 19 Movement is restricted. More specifically, when the front end of the piston head 19e of the piston rod 19 collides with the rear end of the stopper 20, the forward movement of the piston rod 19 is restricted. While the piston rod 19 moves from the firing position shown in FIG. 15 to the collision position where the piston rod 19 collides with the stopper 20 shown in FIG. 16, the piston head 19e exists in the space extending from the piston head 19e to the indenter 2. To compress the air. The compressed air pressure acts on the indenter 2 held at the front end of the holder 3, and the indenter 2 is fired toward the sample 8 by the air pressure. Since the movement of the piston head 19e is restricted by the stopper 20, the piston rod 19 does not contact the indenter 2. As described above, the indenter 2 may be ejected toward the sample 8 by the air pressure acting on the indenter 2.

  As described above, the length of the urging spring 16 can be adjusted by moving the plug 18 supporting the rear end of the urging spring 16 forward or backward with respect to the outer cylinder 12. Therefore, since the biasing force applied by the biasing spring 16 to the piston rod 19 can be adjusted, the collision speed of the indenter 2 ejected by the air compressed by the piston rod 19 can be adjusted. When comparing the restitution coefficients of different samples, it is preferable that the material of the indenter 2 and the collision speed of the indenter 2 are constant. In the restitution coefficient measuring device 1 of the present embodiment, the collision speed of the indenter 2 can be easily adjusted.

  An experiment was performed to confirm that the coefficient of restitution measured using the coefficient of restitution measuring apparatus 1 shown in FIG. 1 was not affected by the mass effect. The sample used in the experiment was a reference piece for a Shore hardness test having a cylindrical shape, and three reference pieces having a nominal hardness of 90 Shore hardness, 60 Shore hardness, and 30 Shore hardness were used. The coefficient of restitution when these reference pieces were fixed to a steel anvil having a mass of 5.7 kg and the coefficient of restitution when fixed to a wooden anvil having a mass of 0.12 kg were measured. FIG. 17 is a top view of the reference piece used in the experiment, and the coefficient of restitution is measured at five measurement points Pa, Pb, Pc, Pd, and Pe shown in FIG. The measurement point Pc is located at the center of the reference piece, and the measurement points Pa and Pe are located at the outer periphery of the reference piece. The measurement point Pb is located between the measurement points Pa and Pc, and the measurement point Pd is located between the measurement points Pc and Pe. As a comparative example, a D-type Shore hardness test and a Leap hardness test were performed on the same measurement points Pa, Pb, Pc, Pd, and Pe.

  The indenter 2 used in the experiment is an alumina bearing ball having a diameter of 2 mm. The mass of the indenter 2 was 0.055 g. The indenter 2 was ejected vertically downward. The length of the biasing spring 16 was adjusted so that the collision speed of the indenter 2 measured using the first optical sensor 24 and the second optical sensor 25 was 10 m / s. The length of the biasing spring 16 can be adjusted by moving the plug 18 forward or backward with respect to the outer cylinder 12.

  FIG. 18A is a graph showing a coefficient of restitution when a reference piece fixed to a steel anvil is measured by the coefficient of restitution measuring device 1, and FIG. 18B is a graph showing a reference piece fixed to a wooden anvil. 3 is a graph showing the restitution coefficient when measured by the restitution coefficient measuring device 1. As shown in FIGS. 18 (a) and 18 (b), the restitution coefficient measured by the rebound velocity measuring device 1 of the present embodiment is different between the case where the reference piece is fixed to the steel anvil and the case where the reference piece is fixed to the wooden anvil. It was confirmed that there was no difference when immobilized was not affected by the mass effect. In addition, it was confirmed that the same coefficient of restitution was measured at all of the five measurement points Pa, Pb, Pc, Pd, and Pe.

  FIG. 19A is a graph showing the Shore hardness when the reference piece fixed to the steel anvil is measured by a D-type Shore hardness tester, and FIG. 19B is fixed to the wooden anvil. It is a graph which shows the Shore hardness when the reference | standard piece measured by the D-type Shore hardness tester is shown. In the D-type Shore hardness test, a diamond indenter and a hammer including an indenter support having the indenter fixed to the tip are dropped from a predetermined drop height onto a reference piece, and the rebound height when the hammer rebounds Measure the height. Shore hardness is obtained by multiplying the ratio of the rebound height to the drop height by a predetermined proportionality constant. The mass of the hammer used in the D-type Shore hardness test was 36.2 g (including the mass of the indenter), and the drop height was 19 mm.

  As shown in FIG. 19A, when the reference piece was fixed to the steel anvil, the same Shore hardness as the nominal Shore hardness of the reference piece was measured. On the other hand, as shown in FIG. 19 (b), when the reference piece is fixed to the wooden anvil, the measured Shore hardness is clearly smaller than the nominal Shore hardness, and the mass effect due to the hammer is measured. It was confirmed that it affected the Shore hardness. In addition, a phenomenon was observed in which the measured Shore hardness gradually decreased from the measurement point at the center to the measurement point at the periphery.

  FIG. 20 (a) is a graph showing the leap hardness when the reference piece fixed to the steel anvil is measured by the leap hardness tester, and FIG. 20 (b) is the reference fixed to the wooden anvil. It is a graph which shows the leap hardness when a piece is measured with a leap hardness tester. The leap hardness test is performed by injecting an impact body including an indenter and an indenter support having the indenter fixed at the tip toward a sample by a spring, and a collision speed before the impact body collides with the sample, This is a hardness test method for measuring the rebound speed of an impact body when it bounces off upon collision. In the leap hardness test, the rebound speed of the impact body relative to the impact speed before the impact body collides with the sample is measured as a coefficient of restitution, and the leap hardness is obtained by multiplying this coefficient of restitution by a predetermined proportional constant. Can be The mass of the impact body used in the leap hardness test was 5.45 g (including the mass of the indenter), and the collision speed before the impact body collided with the sample was 2.1 m / s.

  As shown in FIGS. 20 (a) and 20 (b), the leap hardness of the reference piece fixed to the wooden anvil is smaller than the leap hardness of the reference piece fixed to the steel anvil. Therefore, it was also confirmed in the leap hardness test that the mass effect of the impact body affects the measured hardness. In addition, a phenomenon was observed in which the measured leap hardness gradually decreased from the measurement point at the center to the measurement point at the periphery.

  Instead of the shutter mechanism 50 described with reference to FIGS. 7 to 11, a lid is fixed to the front end of the speed measurement main body 23 of the speed measurement unit 6, and the lid is formed in the indenter passage 23 a formed in the speed measurement main body 23. May be provided with a lid through-hole connected to the cover. FIG. 21A is a cross-sectional view illustrating an example of the lid 70 fixed to the front end of the speed measurement main body 23, and FIG. 21B is a view taken along line I of FIG. 21A. The configuration of the present embodiment other than the lid 70 is the same as the configuration of the above-described embodiment, and thus redundant description will be omitted.

  As shown in FIG. 21A, the lid 70 fixed to the front end of the speed measurement main body 23 has a lid through hole 71 connected to the indenter passage 23a of the speed measurement main body 23. The lid through-hole 71 has a cylindrical shape extending from the front surface 70a of the lid 70 to the rear surface 70b. That is, the diameter D of the lid through-hole 71 of this embodiment is constant from the front surface 70a to the rear surface 70b. The central axis of the lid through-hole 71 coincides with the central axis of the indenter passage 23a. Further, the lid through-hole 71 has a diameter D smaller than the diameter d of the indenter 2 (that is, D <d). Therefore, since the indenter 2 cannot completely pass through the lid through hole 71, the lid 70 prevents the indenter 2 from jumping out of the restitution coefficient measuring device 1.

  When the indenter 2 is ejected from the ejection mechanism 5 with the front surface 70a of the lid 70 in contact with the surface of the sample 8, the collision point at which the indenter 2 collides with the surface of the sample 8 is determined by the center axis of the lid through hole 71 and the sample 8 May slightly deviate from the intersection with the surface. FIG. 22 is a schematic diagram illustrating an example of a distribution of collision points S at which the indenter 2 collides with the surface of the sample 8. As shown in FIG. 22, the collision point S where the indenter 2 ejected from the ejection mechanism 5 collides with the surface of the sample 8 is centered on the intersection X between the central axis of the lid through hole 71 and the surface of the sample 8. Within a circle of radius Rs. Experiments have confirmed that the size of the radius Rs is smaller than 0.1 times the diameter d of the indenter 2. Therefore, when the lid through hole 71 has a diameter D that is at least 0.2 times the diameter d of the indenter 2 (that is, 0.2d <D), the indenter 2 injected from the injection mechanism 5 is attached to the lid 70. It can collide with the surface of the sample 8 without collision.

  The lid through-hole 71 has a diameter D smaller than the diameter d of the indenter 2 so that the indenter 2 does not protrude from the restitution coefficient measuring device 1. On the other hand, when the indenter 2 ejected from the ejection mechanism 5 collides with the lid 70, the lid 70 may be deformed. Therefore, in order to reliably prevent the indenter 2 ejected from the ejection mechanism 5 from colliding with the lid 70, the lid through-hole 71 has a diameter D as large as possible within a range smaller than the diameter d of the indenter 2. It is preferred to have. The diameter D of the lid through-hole 71 is preferably at least 0.5 times the diameter d of the indenter 2, more preferably at least 0.7 times the diameter d of the indenter 2, more preferably the diameter of the indenter 2. d is 0.9 times or more.

  As shown in FIG. 21B, the lid 70 is fixed to the speed measurement main body 23 by three screws (fixing tools) 73. The cover 70 is fixed to the speed measurement main body 23 by engaging the screw 73 with a screw hole (not shown) formed in the speed measurement main body 23. The screw 73 is screwed into a screw hole formed in the speed measurement main body 23 so that the screw 73 does not protrude from the front surface 70a of the lid 70. Thereby, the front surface 70 a of the lid 70 can be brought into direct contact with the surface of the sample 8. The number of screws 73 may be less or more than three. Instead of the screw 73, a hexagonal bolt may be used as a fixture for fixing the lid 70 to the speed measurement main body 23.

  The lid through hole 71 allows a part of the indenter 2 to pass through the lid 70, but the entire indenter 2 cannot pass through the lid 70. Since the lid 70 having such a lid through-hole 71 has a simpler configuration than the above-described shutter mechanism 50, it can be manufactured at a lower cost than the shutter mechanism 50. As a result, the manufacturing cost of the coefficient of restitution measuring device 1 can be reduced. Further, since the diameter D of the lid through hole 71 is smaller than the diameter d of the indenter 2, the indenter 2 ejected from the ejection mechanism 5 is reliably prevented from jumping out of the speed measurement main body 23. As a result, when the indenter 2 is ejected from the ejection mechanism 5 in a state where the front surface 70a of the lid 70 is not in contact with the surface of the sample 8, the indenter 2 collides with an operator near the restitution coefficient measuring device 1. There is no. Therefore, the safety of the worker can be improved. Further, the loss of the indenter 2 can be effectively prevented, so that the burden on the operator can be reduced.

  As shown in FIG. 21A, the speed measuring main body 23 may have an air vent hole 75 extending from a side surface of the speed measuring main body 23 to the indenter passage 23a. By providing the air vent hole 75 in the speed measurement main body 23, the air in the indenter passage 23a is prevented from being compressed by the indenter 2 passing through the indenter passage 23a. When the air in the indenter passage 23a is compressed by the indenter 2 injected from the injection mechanism 5, the collision speed of the indenter 2 may decrease and the rebound speed of the indenter 2 may increase. By providing the air vent hole 75 in the speed measurement main body 23, the indenter passage 23a can be communicated with the outside of the speed measurement main body 23. The air vent hole 75 is preferably provided at a position near the front end of the speed measurement main body 23. Therefore, since the air in the indenter passage 23a is not compressed by the indenter 2 passing through the indenter passage 23a, a more accurate restitution coefficient of the sample 8 can be measured. In this embodiment, two air vents 75 are formed in the speed measurement main body 23, but the number of air vents 75 may be one, or three or more.

  The cross-sectional shape of the air vent hole 75 can be arbitrarily determined. For example, the air vent hole 75 may have a circular cross-sectional shape or a rectangular cross-sectional shape. The size of the air vent hole 75 is preferably smaller than the size of the indenter 2. In this case, the indenter 2 is prevented from jumping out of the speed measurement main body 1 through the air vent hole 75.

  FIG. 23 is a cross-sectional view showing a modification of the lid 70 fixed to the front end of the speed measurement main body 23. In the embodiment shown in FIG. 23, the wall surface 71a of the lid through-hole 71 of the lid 70 is formed in a curved shape. The radius of curvature rc of the wall surface 71a of the lid through hole 71 is constant from the front surface 70a to the rear surface 70b of the lid 70, and is larger than the radius of curvature rd of the outer surface of the indenter 2. Since the indenter 2 has a spherical shape, the radius of curvature rd of the outer surface of the indenter 2 is the same as the radius of the indenter 2 (= d / 2).

Since the wall surface 71a of the lid through hole 71 is formed by a curved surface having a constant radius of curvature rc, the diameter D of the lid through hole 71 gradually decreases from the rear surface 70b of the lid 70 toward the front surface 70a. Therefore, the minimum diameter D _min of the lid through-hole 71 is the diameter of the lid through-hole 71 opened on the front surface 70 a of the lid 70. The minimum diameter D _min of the lid through hole 71 is smaller than the diameter d of the indenter 2. Therefore, since the indenter 2 cannot completely pass through the lid through hole 71, the lid 70 prevents the indenter 2 from jumping out of the restitution coefficient measuring device 1. Further, the minimum diameter D _min of the lid through hole 71 is at least 0.2 times or more the diameter d of the indenter 2. Therefore, the indenter 2 ejected from the ejection mechanism 5 can collide with the surface of the sample 8 without colliding with the lid 70. With such a curved wall surface 71a, the indenter 2 ejected from the ejection mechanism 5 is effectively prevented from colliding with the lid 70.

In order to reliably prevent the indenter 2 ejected from the ejection mechanism 5 from colliding with the lid 70, the minimum diameter D _min of the lid through-hole 71 is preferably at least 0.5 times the diameter d of the indenter 2. Yes, more preferably at least 0.7 times the diameter d of the indenter 2, and even more preferably at least 0.9 times the diameter d of the indenter 2.

  FIG. 24 is a cross-sectional view illustrating another modification of the lid 70 fixed to the front end of the speed measurement main body 23. In the embodiment shown in FIG. 24, a cylindrical portion 23h is formed at the front end of the speed measurement main body 23, and the indenter passage 23a extends to the front end of the cylindrical portion 23h. The lid 70 has a cylindrical stepped portion 70c into which the cylindrical portion 23h is fitted. Although the lid through-hole 71 of this embodiment has a cylindrical shape, as shown in FIG. 23, the wall surface 71a of the lid through-hole 71 may be formed of a curved surface having a constant radius of curvature rc. By fitting the step 70c of the lid 70 into the cylindrical part 23h of the speed measurement main body 23, the central axis of the lid through-hole 71 can be easily matched with the central axis of the indenter passage 23a.

  In the present embodiment, the air vent hole 75 extends from the side surface of the lid 70 to the indenter passage 23a. This air vent hole 75 penetrates through the cylindrical portion 23h of the speed measurement main body 23. As shown in FIG. 23, the air vent hole 75 may extend from the side surface of the lid 70 through the cylindrical portion 23h to the indenter passage 23a.

  An experiment for measuring the coefficient of restitution was performed using the coefficient of restitution measuring instrument 1 in which the lid 70 shown in FIG. 21 was fixed to the front end of the speed measurement main body 23. The sample used in the experiment was a reference piece for a Shore hardness test having a cylindrical shape, and three reference pieces having a nominal hardness of 95 Shore hardness, 80 Shore hardness, and 30 Shore hardness were used. Furthermore, using the same coefficient of restitution measuring device 1, the coefficient of restitution of a reference piece for a Rockwell hardness test having a cylindrical shape was also measured. In the experiment, the ratio of the diameter da of the indenter passage 23a to the diameter d of the indenter 2 (see FIG. 21) was changed, and the effect of the relationship between the diameter da of the indenter passage 23a and the diameter d of the indenter 2 on the measurement result of the coefficient of restitution. Was also evaluated. In addition, the shutter mechanism 50 measured the restitution coefficient of the same reference piece using the restitution coefficient measuring device 1 provided in the speed measurement main body 23, and the obtained measurement result was used as the reference value.

  The indenter 2 used in the first experiment was a ball for bearing made of alumina, and the diameter d of the indenter 2 was 3 mm. The diameter D of the cover through hole 71 is 2.8 mm. Therefore, the lid through-hole 71 has a diameter D that is 0.93 times the diameter d of the indenter 2. The diameter da of the indenter passage 23a is 5 mm. Therefore, the indenter passage 23a has a diameter da 1.67 times the diameter d of the indenter 2. The length of the biasing spring 16 was adjusted so that the collision speed of the indenter 2 became 10 m / s.

  The indenter 2 used in the second experiment was a ball for bearing made of alumina, and the diameter d of the indenter 2 was 3 mm. The diameter D of the cover through hole 71 is 2.8 mm. Therefore, the lid through-hole 71 has a diameter D that is 0.93 times the diameter d of the indenter 2. The diameter da of the indenter passage 23a is 4 mm. Therefore, the indenter passage 23a has a diameter da 1.33 times the diameter d of the indenter 2. The length of the biasing spring 16 was adjusted so that the collision speed of the indenter 2 became 10 m / s.

  The indenter 2 used in the third experiment is a ball for bearing made of alumina, and the diameter d of the indenter 2 is 5 mm. The diameter D of the lid through hole 71 is 4.7 mm. Therefore, the lid through-hole 71 has a diameter D that is 0.94 times the diameter d of the indenter 2. The diameter da of the indenter passage 23a is 7 mm. Therefore, the indenter passage 23a has a diameter da that is 1.4 times the diameter d of the indenter 2. The length of the biasing spring 16 was adjusted so that the collision speed of the indenter 2 became 10 m / s.

  In order to obtain a reference value for comparing the restitution coefficients obtained in the first experiment, the second experiment, and the third experiment, the shutter mechanism 50 is provided with a repulsion coefficient measuring machine 1 provided in the speed measurement body 23. Was used to measure the coefficient of restitution of the same reference piece. The indenter 2 used in the experiment for obtaining the reference value is a ball for bearing made of alumina, and the diameter d of the indenter 2 is 3 mm. The diameter da of the indenter passage 23a is 5 mm. Therefore, the indenter passage 23a has a diameter da 1.67 times the diameter d of the indenter 2. The length of the biasing spring 16 was adjusted so that the collision speed of the indenter 2 became 10 m / s.

  Table 1 shows the restitution coefficient obtained in the first experiment, the second experiment, and the third experiment, and the restitution coefficient measured as a reference value. The restitution coefficient and the reference value shown in Table 1 are the average values of seven restitution coefficients measured at different positions on the sample.

  As is clear from Table 1, the restitution coefficients obtained in the first experiment, the second experiment, and the third experiment are almost the same as the restitution coefficient measured as the reference value. Therefore, the restitution coefficient measuring device 1 in which the lid 70 is fixed to the front end of the speed measurement main body 23 can measure the restitution coefficient without being affected by the mass effect generated by the conventional rebound hardness tester. Further, from the results of the first experiment and the results of the third experiment, it was confirmed that the same coefficient of restitution could be obtained even if indenters 2 having different diameters d were used and the collision speed of the indenters 2 was kept constant. Was.

  The coefficient of restitution obtained in the second experiment is slightly lower than the coefficient of restitution obtained in the first experiment and the coefficient of restitution obtained in the third experiment. On the other hand, the coefficient of restitution obtained in the first experiment and the coefficient of restitution obtained in the third experiment are the same as the reference value. It is considered that this is because the wall surface of the indenter passage 23a and the outer surface of the indenter 2 are too close. Therefore, in order to obtain a more accurate coefficient of restitution, the indenter passage 23a preferably has a diameter da of 1.4 times or more the diameter d of the indenter 2. Also in the case where the shutter mechanism 50 is the restitution coefficient measuring device 1 provided in the speed measuring main body 23, it is preferable that the indenter passage 23a has a diameter da that is 1.4 times or more the diameter d of the indenter 2.

  As described above, according to the coefficient of restitution measuring apparatus 1 according to the above-described embodiment, the coefficient of restitution can be measured without being affected by the mass effect generated in the conventional rebound hardness tester. Further, according to the coefficient of restitution measuring apparatus 1 according to the above-described embodiment, since the indenter 2 is held by the holder 3, there is no restriction on the direction in which the indenter 2 is ejected, and as a result, without being affected by the mass effect. The test can be performed in any direction.

  The coefficient of restitution measuring instrument 1 according to the above-described embodiment can be used as a hardness measuring instrument. That is, the hardness measuring machine includes a holder 3 for holding the spherical indenter 2, an injection mechanism 5 for injecting the indenter 2 held by the holder 3 from the holder 3 toward the sample 8, and an indenter 2 for the sample 8. A speed measuring unit 6 for measuring a collision speed, which is the speed of the indenter 2 before the collision, and a repulsion speed, which is a speed of the indenter 2 after the indenter 2 bounces off the sample 8. Further, the hardness measuring machine has a calculation unit 7, which calculates the sample based on the ratio of the repulsion speed of the indenter 2 to the collision speed of the indenter 2 (that is, corresponding to the above-described coefficient of restitution). Determine a hardness of 8.

  In this hardness measuring machine, as described above, the indenter 2 held by the holder 3 is ejected from the holder 3 toward the sample by the ejection mechanism 5. The speed measuring unit 6 measures the collision speed, which is the speed of the indenter 2 before the indenter 2 collides with the sample 8, and the rebound speed of the indenter 2 after the indenter 2 bounces off the sample 8. Further, the calculation unit 7 determines the hardness of the sample 8 based on the ratio of the repulsion speed of the indenter 2 to the collision speed of the indenter 2. For example, the calculation unit 7 determines the hardness of the sample 8 by multiplying a ratio of the repulsion speed of the indenter 2 to the collision speed of the indenter 2 by a predetermined proportionality constant (for example, 100 or 1000).

  When measuring the hardness of the sample 8 with this hardness measuring device, the collision speed, which is the speed of the indenter 2 before the indenter 2 collides with the sample 8, is controlled to be constant, and the indenter 2 made of the same material is used. By using, the hardness of different samples 8 can be compared. As described above, the collision speed of the indenter 2 can be easily adjusted by moving the plug 18 forward or backward with respect to the outer cylinder 12.

  The above embodiments have been described for the purpose of enabling a person having ordinary knowledge in the technical field to which the present invention pertains to carry out the present invention. Various modifications of the above embodiment can be naturally made by those skilled in the art, and the technical idea of the present invention can be applied to other embodiments. Therefore, the present invention is not limited to the embodiments described, but is to be construed in its broadest scope in accordance with the spirit defined by the appended claims.

REFERENCE SIGNS LIST 1 Restitution coefficient measuring device 2 Indenter 3 Holder 5 Injection mechanism 6 Speed measurement unit 7 Operation unit 8 Sample 10 Display 12 Outer tube 13 Inner tube 14 Firing lever 15 Striker (indenter pressing member)
16 biasing spring 17 rotating shaft 18 plug 19 piston rod (indenter pressing member)
DESCRIPTION OF SYMBOLS 20 Stopper 23 Speed measurement main body 24 1st pass sensor 25 2nd pass sensor 26 3rd pass sensor 30 1st operational amplifier 31 2nd operational amplifier 35 Conversion resistance 36 Conversion resistance 38 Comparator 40 Holder flange member 43 First return spring 44 Second return Spring 46 First guide rod 47 Second guide rod 48 Fastener 50 Shutter mechanism 51 Door 52 First open / close guide 53 Second open / close guide 54 Open / close rod 55 Link mechanism 56 First open / close axis 57 Second open / close axis 58 Open / close spring 60 1 optical fiber 61 second optical fiber 62 third optical fiber 63 fourth optical fiber 70 lid 71 lid through hole 73 screw (fixing tool)
75 Vent hole

Claims (22)

A holder for holding a spherical indenter,
An injection mechanism for injecting the indenter held by the holder toward the sample from the holder,
A collision speed that is the speed of the indenter before the indenter collides with the sample, and a speed measuring unit that measures a repulsion speed that is the speed of the indenter after the indenter bounces off the sample,
An operation unit that calculates a restitution coefficient that is a ratio of the repulsion velocity to the collision velocity ,
The front end of the holder is formed of a plurality of divided portions by forming a slit extending parallel to the axis of the holder,
The said holder holds the outer peripheral surface of the said indenter by the said several division part, The repulsion coefficient measuring machine characterized by the above-mentioned . The holder, restitution coefficient measuring machine according to claim 1, characterized in that you are having a cylindrical shape. A holder for holding a spherical indenter,
An injection mechanism for injecting the indenter held by the holder toward the sample from the holder,
A collision speed that is the speed of the indenter before the indenter collides with the sample, and a speed measuring unit that measures a repulsion speed that is the speed of the indenter after the indenter bounces off the sample,
An operation unit that calculates a restitution coefficient that is a ratio of the repulsion velocity to the collision velocity,
The injection mechanism,
An inner cylinder having a through hole,
An outer cylinder having an inner peripheral surface slidably supported on the outer peripheral surface of the inner cylinder,
An indenter pushing member movable in the through-hole,
An urging spring that is arranged between the outer cylinder and the indenter pushing member and that is contracted by the movement of the outer cylinder to apply an urging force to the indenter pushing member;
The outer cylinder is repulsion coefficient measuring instrument you further comprising a engageable firing lever in a groove formed in an outer surface of the indenter pushing member.   The coefficient of restitution measuring apparatus according to claim 3, wherein the indenter pushing member is a striker that collides with the indenter held by the holder.   The coefficient of restitution measuring apparatus according to claim 3, wherein the indenter pushing member is a piston rod that applies air pressure to the indenter held by the holder. The speed measuring unit,
A speed measurement body having an indenter passage connected to the through hole;
The coefficient of restitution measuring apparatus according to claim 3, further comprising: a first passage sensor and a second passage sensor arranged along the indenter passage.   The apparatus of claim 6, wherein the first and second passage sensors are optical sensors. The speed measurement unit further includes a third passage sensor,
The first passage sensor, the second passage sensor, and the third passage sensor are arranged along the indenter passage,
The computing unit is configured to calculate a speed of the indenter passing between the first pass sensor and the second pass sensor, a speed of the indenter passing between the second pass sensor and the third pass sensor, The acceleration of the indenter is calculated from the above, and the collision speed at the moment when the indenter collides with the sample and the repulsion speed at the moment when the indenter bounces off the sample are calculated. Coefficient of restitution measurement machine.   The apparatus of claim 8, wherein the first, second, and third passage sensors are optical sensors. The speed measuring unit,
A speed measurement body having an indenter passage connected to the through hole;
A first passage sensor and a second passage sensor arranged in the calculation unit,
The first passage sensor is an optical sensor having a first light emitting unit and a first light receiving unit,
The second passage sensor is an optical sensor having a second light projecting unit and a second light receiving unit,
The first light projecting unit irradiates light inside the indenter passage via a first optical fiber, and the first light receiving unit receives light irradiated inside the indenter passage via a second optical fiber,
The second light projecting unit irradiates light inside the indenter passage via a third optical fiber, and the second light receiving unit receives light irradiated inside the indenter passage via a fourth optical fiber. The coefficient of restitution measuring device according to claim 3, wherein: The speed measuring unit,
A speed measurement body having an indenter passage connected to the through hole;
A first passage sensor disposed in the indenter passage,
The calculation unit detects a detection start time of the indenter in the first passage sensor and a detection end time of the indenter in the first passage sensor,
The said operation part calculates the said collision velocity and the said repulsion velocity by dividing the diameter of the said indenter by the time between the said detection start time and the said detection end time, The said collision velocity. Coefficient of restitution measurement machine. The speed measuring unit includes a speed measuring main body having an indenter passage connected to the through hole,
The speed measurement main body is provided with a shutter mechanism that opens the opening of the indenter passage when the speed measurement unit comes into contact with the sample, and closes the opening of the indenter passage when the speed measurement unit moves away from the sample. 4. The coefficient of restitution measuring apparatus according to claim 3, wherein: The shutter mechanism,
A door arranged at the opening of the indenter passage;
An opening and closing rod whose tip projects from the speed measuring body,
13. The coefficient of restitution measuring apparatus according to claim 12, further comprising: a link mechanism configured to convert a movement of the opening / closing bar into an opening / closing operation of the door. The speed measuring unit includes a speed measuring main body having an indenter passage connected to the through hole,
At the front end of the speed measurement main body, a lid having a lid through hole connected to the indenter passage is fixed,
The coefficient of restitution measuring apparatus according to claim 3, wherein the lid through-hole has a diameter larger than 0.2 times the diameter of the indenter and smaller than the diameter of the indenter. The wall surface of the lid through-hole is configured in a curved shape,
The coefficient of restitution measuring apparatus according to claim 14, wherein a radius of curvature of the wall surface is larger than a radius of curvature of the indenter.   16. The coefficient of restitution measuring apparatus according to claim 14, wherein an air vent hole extending from a side surface of the speed measuring main body to the indenter passage is formed in the speed measuring main body.   The coefficient of restitution measuring apparatus according to any one of claims 14 to 16, wherein the indenter passage has a diameter that is at least 1.4 times the diameter of the indenter. The speed measuring unit includes a speed measuring main body having an indenter passage connected to the through hole,
A connection mechanism for connecting the outer cylinder and the holder is further provided,
4. The holder according to claim 3, wherein, when the outer cylinder moves toward the speed measuring unit, the holder moves forward in the indenter passage and holds the indenter in the indenter passage. 5. Coefficient of restitution measurement machine.   19. The coefficient of restitution measuring device according to claim 1, wherein the indenter is made of ceramic.   20. The coefficient of restitution measuring device according to claim 19, wherein the indenter is a bearing ball made of alumina.   The coefficient of restitution measuring apparatus according to any one of claims 1 to 20, wherein a diameter of the indenter is in a range of 0.5 mm to 5 mm. A holder for holding a spherical indenter,
An injection mechanism for injecting the indenter held by the holder toward the sample from the holder,
A collision speed that is the speed of the indenter before the indenter collides with the sample, and a speed measuring unit that measures a repulsion speed that is the speed of the indenter after the indenter bounces off the sample,
An arithmetic unit that determines the hardness of the sample based on a ratio of the repulsion speed to the collision speed ,
The front end of the holder is formed of a plurality of divided portions by forming a slit extending parallel to the axis of the holder,
The hardness measuring device , wherein the holder holds an outer peripheral surface of the indenter by the plurality of divided portions .

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