JP2017090432A - Restitution coefficient measurement machine and hardness measurement machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a restitution coefficient measurement machine which can reduce mass effect, and perform a testing in a free direction.SOLUTION: A restitution coefficient measurement machine 1 comprises: 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; a speed measurement part 6 for measuring collision speed which is speed of the indenter 2 before the indenter 2 collides the sample 8, and restitution speed which is speed of the indenter 2 after the indenter 2 rebounds from the sample 8; and a calculation part 7 for calculating a restitution coefficient which is a ratio of the restitution speed to the collision speed.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a restitution coefficient measuring machine that measures a restitution coefficient used as an index for evaluating the hardness of a sample. Furthermore, this invention relates to the hardness measuring machine which measures the 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, generally, an impactor composed of an indenter made of a hard material such as diamond and an indenter support to which the indenter is fixed is made to collide with the surface of the sample, and the impacted body bounced off from the sample is reflected. The hardness of the sample is measured by measuring the rebound height or rebound speed. Such a rebound hardness test is, for example, a shore hardness test and a leap hardness test.

  The Shore hardness test, which is a rebound hardness test stipulated in JIS (Japanese Industrial Standards), caused the impactor hammer to fall freely from the specified height (falling height) to the sample and bounced 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. The 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 leap hardness test, the impact body, which is an impact body, is injected toward the sample by a spring, the impact speed before the impact body collides with the sample, and the impact body rebound when it collides with the sample and bounces back. This is a hardness test method for measuring speed (that is, speed after impact body collision) (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 a collision body, is measured as a restitution coefficient. The leap hardness is obtained by multiplying the restitution coefficient by a predetermined proportional constant.

  The rebound hardness test, represented by the shore hardness test and the leap hardness test, can easily and quickly perform the hardness test compared to the indentation hardness test such as the Rockwell hardness test and the Vickers hardness test. It has the advantage of being able to. Furthermore, the test machine for the rebound hardness test has the advantage that the structure is simple and the portability is excellent compared to the test machine for the indentation hardness test.

U.S. Pat. No. 4,034,603

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 using such a hammer or impact body to measure the hardness of a small and light sample, 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 in the plastic deformation and elastic deformation of the sample, but also in the vibration of the sample. This is due to the fact that the rebound height or rebound speed that is consumed and is smaller than the rebound height or rebound speed that should be measured is measured. This phenomenon, that is, a phenomenon in which a rebound height or repulsion speed that is smaller than the originally measured rebound height or rebound speed is measured as a result of consumption of the kinetic energy of the colliding body in the vibration of the sample, etc. This is referred to as “mass effect”.

  If a mass effect occurs when measuring the hardness of a sample, an accurate sample hardness cannot be obtained. Therefore, when measuring the hardness of a sample of 4 kg or less in the Shore hardness test, a sufficiently large mass should be used. The test must be carried out with the specimen firmly fixed on its own steel anvil. In the leap hardness test, no dedicated anvil is prepared. Therefore, when measuring the hardness of a small and light sample in the leap hardness test, the user prepares an appropriate table with a sufficiently large mass, and uses a special paste on this table to strengthen the sample. It is necessary to fix to. That is, in order to measure accurate hardness with a conventional rebound hardness tester, there are restrictions on the size and mass of the sample to be tested.

  In the shore hardness test, it is necessary to measure the rebound height after the hammer is allowed to fall freely from a predetermined drop height and collide with the sample. Therefore, the test direction of the shore hardness test is limited to the vertical direction. On the other hand, in the leap hardness test, an impact body is injected toward a sample by a spring, and a restitution coefficient that is a ratio of a rebound 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 in a free direction and the hardness based on the coefficient of restitution.

  As in the case of the Leap Hardness Test, a tester can be used freely if it is a hardness test method that uses the spring to inject the impactor and measures the restitution coefficient of the sample and uses this restitution coefficient as an index for evaluating the hardness of the sample. Hardness test can be performed in any direction. However, even in the case of a leap hardness test, if the sample whose hardness is to be measured is small and light, a mass effect will occur. Accordingly, there is a need for a coefficient of restitution coefficient measuring machine and a hardness measuring machine that can reduce the mass effect and can perform tests in any direction.

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

  In order to achieve the above-described object, one embodiment of the present invention includes 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 the indenter includes: A speed measuring unit that measures a collision speed that is a speed of the indenter before colliding with the sample, and a repulsion speed that is a speed of the indenter after the indenter bounces off the sample; and the repulsion speed with respect to the collision speed And a calculation unit for calculating a coefficient of restitution that is a ratio of the coefficient of restitution.

In a preferred aspect of the present invention, the holder has a cylindrical shape, and the front end of the holder is formed of a plurality of divided portions by forming a slit extending in parallel with the axis of the holder, The holder is characterized in that the outer peripheral surface of the indenter is held by the plurality of divided portions.
In a preferred aspect of the present invention, the injection mechanism includes an inner cylinder in which a through hole is formed, an outer cylinder having an inner circumferential surface that is slidably supported on the outer circumferential surface of the inner cylinder, and the inside of the through hole. A movable indenter extruding member; and an urging spring that is disposed between the outer cylinder and the indenter extruding member and contracts by the movement of the outer cylinder to apply an urging force to the indenter extruding member, The outer cylinder has a firing lever that can be engaged with a groove formed on the outer surface of the indenter pushing member.
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 providing.
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 measurement 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 computing unit passes through between the first passage sensor and the second passage sensor, and 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 into the indenter passage through the first optical fiber, the first light receiving unit receives the light irradiated into the indenter passage through the second optical fiber, and the second light receiving unit The light projecting unit irradiates light into the indenter passage through a third optical fiber, and the second light receiving unit receives light irradiated into the indenter passage through 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 disposed in the indenter passage, and the calculation unit includes: The indenter detection start point in the first passage sensor and the indenter detection end point in the first passage sensor are detected, and the calculation unit determines the diameter of the indenter as the detection start point and the detection end point. 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 measurement unit includes a speed measurement main body having an indenter passage connected to the through hole, and the speed measurement main body includes the speed measurement unit when the speed measurement unit contacts the sample. A shutter mechanism is provided that opens the 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 bar protruding from the speed measuring body, and the movement of the opening / closing bar is converted into an opening / closing operation of the door. And a link mechanism.

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 has a lid through hole connected to the indenter passage at a front end of the speed measurement main body. The 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, the wall surface of the lid through hole is formed in a curved surface, and the curvature radius of the wall surface is larger than the curvature radius 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 measurement unit includes a speed measurement main body having an indenter passage connected to the through hole, and further includes a coupling mechanism that couples the outer cylinder and the holder. When moving toward the speed measurement unit, the holder moves forward in the indenter passage to hold 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 indenter has a diameter in the range of 0.5 mm to 5 mm.

  Another aspect of the present invention includes a holder for holding a spherical indenter, an injection mechanism for injecting the indenter held by the holder from the holder toward the sample, and the indenter before the indenter collides with the sample. A velocity measuring unit that measures a collision velocity that is a velocity of the indenter and a rebound velocity that is a velocity of the indenter after the indenter bounces off the sample; and a ratio of the repulsion velocity to the collision velocity of the sample. A hardness measuring machine comprising: a calculation unit that determines hardness.

According to the restitution coefficient measuring machine of the present invention, the collision object (object) that collides with the sample in order to measure the restitution coefficient is only a spherical indenter. That is, the colliding body that collides with the sample does not include an indenter support to which the indenter is fixed, unlike a hammer for a Shore hardness test or an impact body for a leap hardness test. As a result, the mass of the collision object (object) that collides with the sample can be greatly reduced, so that the mass effect generated when measuring the restitution coefficient is greatly reduced, and the restitution coefficient 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, since there is no restriction | limiting in the direction which injects an indenter, it can test in a free direction.
Furthermore, according to the hardness measuring machine of the present invention, the collision object (object) that collides with the sample to measure the hardness is only a spherical indenter. As a result, the mass of the collision object (object) that collides with the sample can be greatly reduced, so that the mass effect that occurs when measuring the hardness is greatly reduced, and the hardness of the sample can be accurately measured. .

It is a schematic sectional drawing of the restitution coefficient measuring machine concerning one embodiment of the present invention. Fig.2 (a) is an enlarged side view of the front end of a holder, FIG.2 (b) is CC sectional view taken on the line of Fig.2 (a). It is a schematic sectional drawing which shows the state where the striker was pushed ahead by the restoring force of the biasing spring when the engagement between the hook of the launch lever and the groove of the striker was released. It is the schematic which shows the structure of the electric circuit of a 1st optical sensor. It is the schematic for demonstrating the method to measure the passage time after an indenter passes a 1st optical sensor until it passes a 2nd optical sensor. It is the schematic which shows a mode that the indenter after measuring a restitution coefficient is again hold | maintained at a holder. It is the schematic sectional drawing which showed an example of the speed measurement main body provided with the shutter mechanism. 8A is a cross-sectional 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 a GG sectional view taken on the line b). 9A is a view taken in the direction of the arrow E in FIG. 7, and FIG. 9B is a cross-sectional view taken along the line HH in FIG. 9A. It is a schematic diagram which shows the state from which the 1st door and the 2nd door separated from each other by the link mechanism, and the opening of the indenter channel | path was opened. It is a mimetic diagram showing the state where the 1st door and the 2nd door contacted mutually 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. It is explanatory drawing of the method of calculating | requiring the impact speed at the moment when an indenter collides with a sample, and the repulsion speed at the moment when an indenter bounces off a sample. It is the schematic which shows the speed measurement part which concerns on another embodiment. It is a schematic sectional drawing of the coefficient of restitution coefficient which concerns on another embodiment. It is a schematic sectional view showing a state where 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 | standard piece used for experiment. FIG. 18 (a) is a graph showing the coefficient of restitution when the reference piece fixed to the steel anvil is measured with a coefficient of restitution measuring instrument, and FIG. 18 (b) shows the reference piece fixed to the wooden anvil. It is a graph which shows a restitution coefficient when it measures with a restitution coefficient measuring machine. FIG. 19 (a) is a graph showing the shore hardness when a reference piece fixed to a steel anvil is measured with a D-type shore hardness tester, and FIG. 19 (b) is fixed to a wooden anvil. It is a graph which shows a shore hardness when the reference | standard piece measured with a D type Shore hardness tester. FIG. 20 (a) is a graph showing the leap hardness when a reference piece fixed to a steel anvil is measured with a leap hardness tester, and FIG. 20 (b) is a reference fixed to a wooden anvil. It is a graph which shows the leap hardness when a piece is measured with a leap hardness tester. Fig.21 (a) is sectional drawing which shows an example of the lid | cover fixed to the front end of the speed measurement main body, FIG.21 (b) is an I line arrow directional view of Fig.21 (a). It is a schematic diagram which shows an example of 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 | cover fixed to the front end of the speed measurement main body. It is sectional drawing which shows another modification of the lid | cover fixed to the front end of the speed measurement main body.

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

  A restitution coefficient measuring machine 1 shown in FIG. 1 includes a holder 3 that holds a spherical indenter 2, an injection mechanism 5 that injects the indenter 2 held by the holder 3 toward the sample 8, and an indenter 2. A velocity measuring unit 6 for measuring a collision speed, which is a speed of the indenter 2 before colliding with the sample 8, and a repulsion speed of the indenter 2 after the indenter 2 collides with the sample 8 and bounces; And an arithmetic unit 7 for calculating a coefficient of restitution that is a ratio of the rebound speed. The calculation unit 7 is disposed inside the display 10 having a display unit 10a that displays the coefficient of restitution 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 3 a by forming slits 3 b extending in parallel with the axis of the holder 3. . In the illustrated example, the front end of the holder 3 is composed of four divided portions 3a by four slits 3b. The front end of the holder 3 may be constituted by three or less divided parts 3a, or may be constituted by 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 dividing portion 3 a is slightly 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 a cylindrical shape. For example, the holder 3 may have a polygonal cylinder shape such as a square cylinder shape or a pentagonal cylinder 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 holder 3 having a cylindrical shape is pressed against the indenter 2, the divided portion slightly extends 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 includes an inner cylinder 13 in which a through hole 13 a is formed, and an inner peripheral surface 12 a that is slidably supported on an outer peripheral surface 13 b of the inner cylinder 13. The outer cylinder 12, the striker 15 movable in the through hole 13a, and the outer cylinder 12 are disposed between the striker 15 and contracted by the movement of the outer cylinder 12 to apply a biasing force to the indenter pushing member 15. And a spring 16. Furthermore, the injection mechanism 5 shown in FIG. 1 includes a stopper 20 that restricts 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. As will be described later, 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 biasing spring 16.

  The striker 15 of this embodiment has a bar shape. More specifically, the striker 15 includes 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 portion 15b by the rear end of the striker main body 15a being embedded in the front end of the main body support portion 15b. The central axis of the striker main body 15a coincides with the central axis of the main body support portion 15b. Although the striker main body 15a of this embodiment is comprised from the main body support part 15b and another member, the striker main body 15a and the main body support part 15b may be integrally formed. For example, the striker body 15 a can be formed on the striker 15 by grinding a cylindrical member.

  The front end of the urging spring 16 is inserted into a guide hole 15c formed in the main body support portion 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 coincides with the central axis of the main body support portion 15b. A plug 18 that closes 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 this 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 on 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, since the length of the biasing spring 16 can be easily changed, the biasing force applied to the striker 15 by the biasing spring 16 can be easily changed.

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

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

  FIG. 3 schematically shows a state where 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 14 a of the firing lever 14 and the groove 15 d 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 stopper 20 having a cylindrical shape 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 support portion 15b of the striker 15 collides with the rear end of the stopper 20, the forward movement of the striker 15 is limited. While the striker 15 moves from the firing position shown in FIG. 1 to the collision position where the striker 15 collides with the stopper 20 shown in FIG. 3, the front end of the striker body 15 a 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 forward of the injection mechanism 5, the hook 14 a of the firing lever 14 includes a through hole 12 b formed on the side surface of the outer cylinder 12 and a side surface of the inner cylinder 13. The outer surface of the striker 15 is in contact with the first elongated hole 13e formed on the outer surface of the striker 15.

  As described above, the length of the urging spring 16 can be adjusted by moving the plug 18 that supports the rear end of the urging spring 16 forward or backward relative to the outer cylinder 12. Therefore, since the urging force applied to the striker 15 by the urging spring 16 can be adjusted, the collision speed of the indenter 2 injected by the striker 15 can be adjusted. When comparing the restitution coefficients of different samples, the material of the indenter 2 and the impact speed of the indenter 2 are preferably 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 embodiment mentioned above has a rod shape, the shape of the striker 15 is not limited to a rod shape. The shape of the striker 15 is arbitrary as long as it collides with the indenter 2 held by the holder 3 and the indenter 2 can be ejected 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 injected by the striker 15 collides with the sample 8, and the indenter 2 A speed measuring unit 6 that measures the repulsion speed of the indenter 2 after it bounces off when it collides with 8 is fixed. The speed measurement unit 6 of the present embodiment is attached to the front end of the inner cylinder 13 and has a speed measurement main body 23 formed with an indenter passage 23a through which the indenter 2 passes, and a first passage sensor arranged along the indenter passage 23a. 24 and the second passage sensor 25. The indenter passage 23 a is connected to the through hole 13 a of the inner cylinder 13. The first passage sensor 24 and the second passage sensor 25 are arranged along the indenter passage 23 a, and the first passage sensor 24 is located in front of the speed measurement main body 23 with respect to the second passage sensor 25. “Pass sensor” is a generic term for sensors that can detect the passage of an object. This passage sensor includes, for example, an optical sensor or a magnetic sensor.

  The first passage sensor 24 of 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 the light emitted 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 the light emitted 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.

  In the present embodiment, a light emitting diode (LED) is used for the first light projecting unit 24a and the second light projecting unit 25a, 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 projection slit (not shown) disposed 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. Light passing through a light receiving slit (not shown) is received. Similarly, light from the second light projecting portion 25a is irradiated into the indenter passage 23a through a light projecting slit (not shown) disposed on the wall surface of the indenter passage 23a, and the second light receiving portion 25b is irradiated with the indenter passage 23a. The light which passed through the light-receiving slit (not shown) arrange | positioned at the wall surface of is received. In the present embodiment, the first light projecting unit 24 a and the first light receiving unit 24 b of the first light sensor 24 are disposed at a position 10 mm from the front end of the speed measurement main body 23, and the second light projecting of the second light sensor 25. The part 25 a and the second light receiving part 25 b are disposed at a position 20 mm from the front end of the speed measurement main body 23.

  The first light sensor 24 detects that the light irradiated from the first light projecting unit 24 a is blocked by the passage of the indenter 2, so that the indenter 2 detects the first light sensor 24. Detects passing. 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 has been blocked by the passage of the indenter 2, and thereby the indenter 2 detects the second light. The passage through the sensor 25 is detected. The calculation unit 7 measures the passage 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 this embodiment). Therefore, the calculation unit 7 calculates the time between the passage of the indenter 2 through the second optical sensor 25 and the passage of the first optical sensor 24 and the interval 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 passage time from when the indenter 2 passes through the first optical sensor 24 to when it passes through the second optical sensor 25 and between the first optical sensor 24 and the second optical sensor 25. The repulsion speed of the indenter 2 can be calculated from the distance of

  FIG. 4 is a schematic diagram showing the configuration of the electric circuit of the first photosensor 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 photosensor 25 is the same as the configuration of the electric circuit of the first photosensor 24, the overlapping description is omitted.

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

  The voltage Vopa output from the first operational amplifier 30 is input to the negative input terminal 31 b of the second operational amplifier 31 via the delay circuit 32. A predetermined base voltage Vdet is input to the positive input terminal 31 a of the second operational amplifier 31. The second operational amplifier 31 outputs 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, from the output terminal 31c of the second operational amplifier 31. . 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 38 a of the comparator 38. A voltage Vcmp, which is a preset threshold value, is input to the negative input terminal 38 b 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 a signal VS from the output terminal 38c of the comparator 38 when the voltage Vopa is larger 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 24 a 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 has a first light projecting unit that is an LED according to the output current of the first light receiving unit 24b so that the output current of the first light receiving unit 24b that is a photodiode is constant. A feedback circuit for automatically changing the light emission amount 24a is included.

  The first light receiving unit 24b that is a photodiode that receives light emitted from the first light projecting unit 24a that is an LED, when the light from the first light projecting unit 24a is not blocked by the passage of the indenter 2, It is preferable to always output a constant current. However, the light emission amount of the LED differs depending on the environment (for example, temperature and humidity) in which the LED is arranged. Similarly, the current output from the photodiode varies depending on the environment (for example, temperature and humidity) in which the photodiode is disposed. Furthermore, since there are individual differences in LEDs, when the same current is passed through different LEDs having the same structure, the light emission amount of each LED is different. Similarly, since there are individual differences in photodiodes, when different photodiodes having the same structure receive the same amount of light, the currents output by the 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 machine 1 is used, and thus there is a possibility that an accurate restitution coefficient cannot be measured. . 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 for each measurement. Similarly, when the electric circuit shown in FIG. 4 is not used, the voltage Vopa output from the operational amplifier 30 of the different coefficient of restitution coefficient 1 is different in each coefficient of restitution coefficient measuring machine 1, and therefore, an accurate coefficient of restitution can be measured. 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 with 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 to 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 24 a and / or the output current of the first light receiving unit 24 b with each restitution coefficient measuring device 1. Since the configuration of the electric circuit of the second photosensor 25 has the same configuration as the configuration of the electric circuit of the first photosensor 24, the second photosensor 25 can obtain the same advantages.

  FIG. 5 is a schematic diagram for explaining a method of measuring a 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. That is, FIG. 5 is a schematic diagram for explaining a method of measuring the repulsion speed of the indenter 2 that has collided with the sample 8 and bounced back. 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 with time.

  The indenter 2 that has bounced off the sample 8 moves to the position where the first optical sensor 24 is disposed. When the indenter 2 blocks the light emitted by 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 of light blocked by the first light receiving unit 24b gradually decreases and then gradually increases. Accordingly, 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 is 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 compared with the voltage Vcmp that is a threshold value. When the output voltage Vopa of the first operational amplifier 30 is larger than the voltage Vcmp, the comparator 38 outputs the signal VS. When the output voltage Vopa of the first operational amplifier 30 is smaller than the threshold voltage Vcmp, the comparator 38 stops outputting the signal VS. As a result, a rectangular wave RA obtained by converting the wave SA having a convex waveform by the comparator 38 is input to the calculation unit 7.

  The computing unit 7 detects a time Ta when the signal VS from the comparator 38 is output and a time Tb when the output of the signal VS is stopped. That is, the time point Ta is a detection start time point when the calculation unit 7 starts detecting the passage of the indenter 2 in the first optical sensor 24, and the time point Tb is a time point when the calculation unit 7 passes the indenter 2 in the first optical sensor 24. This is the detection end point when the detection is completed. Further, the calculation unit 7 calculates a time point Td obtained by dividing time Tc from the time point Ta being detected until the time point Tb is detected by half. The time Tc corresponds to the 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 photosensor 25 is disposed. When the indenter 2 blocks the light emitted from 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 of light blocked by the second light receiving unit 25b gradually decreases and then gradually increases. Accordingly, the amount of light received by the second light receiving unit 25b gradually decreases and then gradually increases. Therefore, the output voltage Vopa of the first operational amplifier 30 is 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 compared with the voltage Vcmp that is a threshold value. When the output voltage Vopa of the first operational amplifier 30 is larger than the voltage Vcmp, the comparator 38 outputs the signal VS. When the output voltage Vopa of the first operational amplifier 30 is smaller 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 a convex waveform by the comparator 38 is input to the calculation unit 7.

  The computing unit 7 detects a time Te when the signal VS from the comparator 38 is output and a time Tf when the output of the signal VS is stopped. That is, the time point Te is a detection start time point when 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 when the calculation unit 7 passes the indenter 2 in the second optical sensor 25. This is the detection end point when the detection is completed. Further, the calculation unit 7 calculates a time point Th obtained by dividing a time Tg from when the time point Te is detected until the time point Tf is detected by half. The time Tg corresponds to the 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 point Td and the time point Th 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. Further, the calculation 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 passage 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 until it passes through the second optical sensor 25. When the time between the time point Td and the time point Th is used as the passage time T1, for example, the measurement error of the passage time T1 is made smaller than when the time between the time point Ta and the time point Te is used as the passage time. Is possible, and a more accurate repulsion rate can be calculated.

  The collision speed of the indenter 2 is calculated by the calculation unit 7 using the same 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 it passes through the first optical sensor 24, whereby the collision speed is calculated by the calculation unit 7. The calculation unit 7 further calculates a restitution coefficient that is a ratio of the rebound speed to the collision speed.

  Although not shown, the second optical sensor 25 may be omitted, and the calculation unit 7 may calculate the collision speed and the repulsion speed of the indenter 2 using only the first optical sensor 24. For example, the calculation unit 7 sets the diameter of the indenter 2 to the time point Ta (that is, the detection start time of the indenter 2 in the first optical sensor 24) and the time point Tb (that is, the detection end time of the indenter 2 in the first optical sensor 24). The calculation unit 7 may calculate the repulsion speed of the indenter 2 by dividing the time Tc 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.

  Thus, when the repulsion 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 disposed close to the surface of the sample 8, an accurate restitution coefficient can be measured.

  As shown in FIG. 1, the holder 3 is inserted from the front end of the inner cylinder 13 toward the rear end. The outer cylinder 12 is formed with an outer cylinder flange portion 12 c that protrudes radially outward of the outer cylinder 12, and the inner cylinder 13 is formed with an inner cylinder flange portion 13 c that protrudes radially outward of the inner cylinder 13. Has been. A holder flange member 40 is fixed to the outer peripheral surface of the holder 3. The holder flange member 40 includes a cylindrical fixing portion 40 a that is fixed to the outer peripheral surface at the rear end of the holder 3, and a protruding flange portion 40 b that protrudes radially outward of the holder 3 from the fixing portion 40 a. The inner cylinder 13 is formed with a second long hole 13d penetrating the side surface of the inner cylinder 13 and extending along the longitudinal direction of the inner cylinder 13, and the projecting flange portion 40b of the holder flange member 40 has a second shape. 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. The first return spring 43 connects the inner cylinder flange portion 13c to the outer cylinder flange. Biasing is performed in a direction away from the portion 12c. Further, the coefficient of restitution measuring device 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. Biasing is performed in a direction away from the portion 12c. A first guide rod 46 extending to the outer cylinder flange portion 12c through the first through hole 40c formed in the protruding flange portion 40b until passing through the protruding flange portion 40b is fixed. The first guide rod 46 extends through the inside of the second return spring 44, and the protruding flange portion 40 b is provided on the first guide rod 46 by the urging force of the second return spring 44. A fastener 48 is fixed to restrict movement in a direction away from the fastener. A second guide rod 47 extending to the inner cylinder flange portion 13c through the second through hole 40d formed in the projecting flange portion 40b and penetrating the projecting flange portion 40b is fixed.

  The outer cylinder flange portion 12 c 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 coupling mechanism 39 that couples the holder 3 to the outer cylinder 12.

  FIG. 6 is a schematic diagram showing how the indenter 2 after measuring the coefficient of restitution is held by the holder 3 again. As shown in FIG. 6, in order to hold the indenter 2 again in the holder 3, the operator forms the hook 14 a of the firing lever 14 on the outer surface of the striker 15 against the biasing force of the first return spring 43. The outer cylinder 12 is pushed toward the inner cylinder 13 until the groove 15d is engaged. At this time, the holder 3 connected to the outer cylinder 12 by the connecting mechanism 39 moves forward in the indenter passage 23 a 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 in the side surface of the inner cylinder 12, the holder flange member 40 also moves toward the front of the coefficient of restitution coefficient measuring machine 1. be able to. Since the urging force is applied to the holder flange member 40 fixed to the holder 3 by the second return spring 44, the holder 3 maintains the distance between the holder 3 and the outer cylinder 12 while maintaining the coefficient of restitution. It moves toward the front of the measuring machine 1. The holder 3 that moves toward the front of the coefficient of restitution measuring instrument 1 moves forward in 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. As a result, the indenter 2 is held at the tip of the holder 3.

  Since the striker 15 is restricted from moving forward by the stopper 20 by the stopper 20, the striker 15 cannot move when the outer cylinder 12 is pushed into the inner cylinder 13, while the biasing spring 16 is Shrinked. The hook 14 a of the firing lever 14 fixed to the outer cylinder 12 moves along the first long hole 13 e formed in the side surface of the inner cylinder 12 and engages with a groove 15 d formed in the outer surface of the striker 15. When the pressing force that pushes the outer cylinder 12 toward the inner cylinder 13 is released, the outer cylinder 12 moves toward the rear side of the coefficient of restitution coefficient 1 by the urging force of the first return spring 43. At this time, the striker 15 with which the hook 14a engages also moves rearward, and the striker 15 stands by 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 the outer cylinder 12 is pushed into the inner cylinder 13, the holder 3 is guided by the second guide rod 47. Therefore, 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 simply pushing the outer cylinder 12 into the inner cylinder 13. Therefore, it is possible to reduce the burden on the operator when continuously measuring the coefficient of restitution.

  According to the restitution coefficient measuring device 1 of the present embodiment, the collision object (object) that collides with the sample 8 in order to measure the restitution coefficient is only the spherical indenter 2. That is, the colliding body that collides with the sample 8 does not include an indenter support to which the indenter 2 is fixed, unlike a hammer for a Shore hardness test or an impact body for a leap hardness test. As a result, the mass of the collision object (object) that collides with the sample can be greatly reduced, so that the mass effect generated when measuring the restitution coefficient is greatly reduced, and the restitution coefficient of the sample can be accurately measured. . 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, since there is no restriction | limiting in the direction which injects the indenter 2, a test can be performed in a free direction. Furthermore, according to the restitution coefficient 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 relative to the outer cylinder 12.

  According to the restitution coefficient measuring apparatus 1 of the present embodiment that can greatly reduce the mass effect and can perform tests in any direction, the restitution coefficient of various samples 8 can be measured. For example, not only the restitution coefficient of a metal material but also the restitution coefficient of a non-metallic material such as a food such as chocolate or bonito, or ceramic, marble, or glass can be measured. Further, the colliding body that collides with the sample 8 is only the spherical indenter 2, and the volume of the colliding body is very small. Therefore, the heat capacity of the collision body is small. Moreover, the time when the indenter 2 contacts the sample 8 is instantaneous. As a result, since the amount of change in the surface temperature of the sample 8 due to the test can be greatly suppressed, the restitution coefficient of the high-temperature or low-temperature sample 8 can be accurately measured.

  Furthermore, in the coefficient of restitution measuring instrument 1 of the present embodiment, the indenter 2 having various diameters is 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 the smallest possible diameter. On the other hand, when measuring the coefficient of restitution of the sample 8 with minute irregularities formed on the surface, the rebound direction of the indenter 2 from the sample 8 deviates greatly from the injection direction of the indenter 2 from the injection mechanism 5. (Tilt) may occur. This is because the diameter of the indenter 2 is too small with respect to 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 generation 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 the indenter 2 having a very small diameter is used, the operator easily loses the indenter 2. Therefore, from the viewpoint of working efficiency, the diameter of the indenter 2 is preferably 0.5 mm or more. Furthermore, before measuring the coefficient of restitution, it is more preferable that the diameter of the indenter 2 has a diameter of 2 mm or more in order to confirm whether the indenter 2 is broken and / or missing. That is, the diameter range of the indenter 2 is preferably 0.5 mm or more and 5 mm or less, and more preferably 2 mm or more and 5 mm or less.

  The speed measurement unit 6 of the restitution coefficient measuring device 1 of the present embodiment measures the collision speed and rebound speed of the indenter 2 using the optical sensors 24 and 25. Therefore, there is no restriction | limiting in the material of the indenter 2, For example, the indenter 2 may be comprised from metal materials, such as a cemented carbide, and may be comprised from nonmetallic materials, such as a ceramic and a diamond. Preferably, the indenter 2 is a bearing ball made of alumina which is ceramic. Since the bearing ball made of alumina has a high sphericity, the restitution coefficient measuring instrument 1 can measure an accurate restitution coefficient with high reproducibility. Bearing balls made of alumina are inexpensive and easily available on the market.

  An opening of the indenter passage 23a of the speed measurement main body 23 is opened in the speed measurement main body 23 of the speed measurement section 6 when the speed measurement section 6 contacts the sample 8, and the speed measurement main body when the speed measurement section 6 moves away from the sample 8. A shutter mechanism 50 for closing the opening of the 23 indenter passages 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 according to this embodiment includes a door 51 disposed at the opening of the indenter passage 23 a, an opening / closing bar 54 whose tip protrudes from the speed measuring body 23, and movement of the opening / closing bar 54. A link mechanism 55 that converts the door 51 to open and close. The speed measurement main body 23 of the present embodiment includes a first member 23b in which an indenter passage 23a is formed, a door 51 is disposed, and a second member 23c in which an opening / closing bar 54 is disposed.

  8A is a cross-sectional 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 a GG sectional view taken on the line b). As shown in FIG. 8A, the door 51 of the present embodiment includes a first door 51 a and a second door 51 b that open and close the opening of the indenter passage 23 a of the speed measurement main body 23 by a link mechanism 55. The link mechanism 55 will be described later. When the first door 51a and the second door 51b come into contact with 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 FIG. 8A and FIG. 8B, a first opening / closing guide 52 having a first arcuate surface 52a is fixed to the side surface of the first door 51a, and the second door 51b has a first door A second opening / closing guide 53 having two arcuate surfaces 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 are opposed to each other. The first opening / closing guide 52 is rotatably fixed to the first member 23 b 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 51 a 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 23 b via the second opening / closing shaft 57. That is, the second opening / closing guide 53 can rotate around the second opening / closing shaft 57, and as a result, the second door 51 b fixed to the second opening / closing guide 53 rotates around the second opening / closing shaft 57. be able to.

  As shown in FIGS. 8 (b) and 8 (c), a first housing portion 51c (FIG. 8 (b)) in which an arc-shaped first slope surface 51d is formed in the central region of the first door 51a. Reference) is formed. Also in the central region of the second door 51b drawn with a virtual line (one-dot chain line) in FIG. 8C, a second accommodating portion 51f having an arcuate second slope surface 51e is formed. When the 1st door 51a and the 2nd door 51b mutually contact | abut, the indenter 2 can be accommodated in the internal space comprised by the 1st accommodating part 51c and the 2nd accommodating part 51f.

  9A is a view taken in the direction of the arrow E in FIG. 7, and FIG. 9B is a cross-sectional view taken along the line HH in FIG. 9A. As shown in FIG. 9A, one end of an opening / closing spring 58 is fixed to the rear end of the opening / closing rod 54, and the other end of the opening / closing spring 58 is fixed to the second member 23c. In this state, the front end of the open / close bar 54 projects forward from the front end of the second member 23c. As shown in FIGS. 9A and 9B, a cylindrical first protrusion 54a and a second protrusion 54b are formed on the side surface of the opening / closing rod 54, and the first protrusion 54a It is located in front of the opening / closing bar 54 with respect to the two protrusions 54b. The first protrusion 54a and the second protrusion 54b protrude from the side surface of the opening / closing bar 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, first and second protrusions 54 a and 54 b formed on the opening / closing bar 54, and an opening / closing spring 58. FIG. 10 is a schematic diagram showing a state in which the opening of the indenter passage 23a is opened by the link mechanism 55 rotating the first door 51a and the second door 51b away from each other. FIG. 11 is a schematic diagram showing a state in which the first door 51a and the second door 51b are brought into contact with 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 measurement main body 23 of the speed measurement unit 6 is brought into contact with the surface of the sample 8, the open / close bar 54 opposes the urging force of the open / close spring 58. Is pushed in until it is accommodated inside the speed measuring body 23. At this time, the first protrusion 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 door 51a. The first opening / closing guide 52 and the second opening / closing guide 53 are rotated about the first opening / closing shaft 56 and the second opening / closing shaft 57, respectively, in the 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 measuring body 23 is opened, and the indenter 2 can collide with the surface of the material 8.

  As shown in FIG. 11, when the speed measurement main body 23 of the speed measurement unit 6 is separated from the surface of the sample 8, the opening / closing bar 54 is speed-measured by the restoring force of the opening / closing spring 58. It advances until it protrudes from the front end of the main body 23. At this time, the second protrusion 54b formed on the opening / closing rod 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 first door The first opening / closing guide 52 and the second opening / closing guide 53 are rotated about the first opening / closing shaft 56 and the second opening / closing shaft 57, respectively, in the direction in which the two doors 51b come into contact with 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 formed by the first accommodating portion 51c and the second accommodating portion 51f (see FIG. 8C). . At this time, since the indenter 2 is guided to the first slope surface 51d formed in the first housing portion 51c and the second slope surface 51e formed in the second housing portion 51f, the indenter 2 is guided to the first door. It is prevented from being sandwiched between 51a and the second door 51b.

  According to the shutter mechanism 50 of the present embodiment, the opening of the indenter passage 23 a 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, the loss of the indenter 2 injected from the injection mechanism 5 can be effectively prevented, so that the burden on the operator can be reduced.

  FIG. 12 is a schematic diagram showing a speed measurement unit 6 according to another embodiment. The speed measurement unit 6 illustrated in FIG. 12 includes 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 “pass sensor” is a general term for sensors that can detect the passage of an object, and the pass 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 23 a, and the first optical sensor 24 is based on the second optical sensor 25 and the third optical sensor 26. Is positioned in front of the speed measuring body 23, and the second optical sensor 25 is positioned in front of the speed measuring body 23 relative to 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 the 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 electrical circuit of the third photosensor 26 is the same as the configuration of the electrical circuit of the first photosensor 24 described with reference to FIG. That is, the light emission amount of the third light projecting unit 26a is automatically set 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 with.

  The coefficient of restitution measuring device 1 according to the embodiment described so far can perform a test in a free direction. For example, the indenter 2 can be injected upward or can be injected downward. When the indenter 2 is ejected in different directions, gravity in different directions acts on the indenter 2. Therefore, a small error may occur in the measured restitution coefficient depending on the injection direction of the indenter 2. In particular, when the impact speed and repulsion speed of the indenter 2 are slow, the influence of gravity becomes large. 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 bounces off the surface of the sample 8 is used as the repulsion speed. It is preferable to calculate. 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 rebounds from the sample 8 will be described with reference to FIG.

  FIG. 13 is an explanatory view of a method for 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 bounces off the sample 8 by calculation. In FIG. 13, the point Ps represents the surface of the sample 8, the point P <b> 1 represents the position of the first optical sensor 24, the point P <b> 2 represents the position of the second optical sensor 25, and the point P <b> 3 represents the position of the third optical sensor 26. Represents. Hereinafter, a method for calculating the collision speed of the indenter 2 at the moment when the indenter 2 passes through the point P3, the point P2, and the point P1 in this order and reaches the point Ps 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. Furthermore, the average speed between the points P3 and P2 is v23, the average speed between the points P2 and P1 is v12, and the average speed between the points P3 and P1 is v13. The distance from the point P3 to the point P2 is L23, the distance from the point P2 to the point P1 is L12, the distance from the point P3 to the point P1 is L13, and the distance from the point P3 to the point Ps is Ls. is there. The control unit 7 uses the method described with reference to FIG. 5 to determine the time T23 from when the indenter 2 passes the point P3 until it passes the point P2, and the point P1 after the indenter 2 passes the point P2. The time T12 until passing and the time T13 until the indenter 2 passes the point P3 after passing the point P3 are measured.

The average speed v23 between the point P3 and the point P2 can be calculated by the following equation (1) from the time T23 measured by the control unit 7 and the known L23.
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 an equal acceleration of α, the relationship of the following expression (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 equation (5) is established for the velocity v12, the velocity v1, and the velocity v2, and the relationship of the following equation (6) is established for the velocity v13, the velocity v1, and the velocity v3.
v12 = (v1 + v2) / 2 (5)
v13 = (v1 + v3) / 2 (6)
From the equations (4), (5), and (6), the following equations (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)
Since the calculation unit 7 obtains the speed v23, the speed v12, and the speed v13 by the above-described calculation formulas (1), (2), and (3), the calculation unit 7 has the formulas (7) and (8). , And equation (9), the speed v1, the speed v2, and the speed 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 moving at a constant acceleration α, the collision velocity vs of the indenter 2 at the moment of collision with the point Ps (that is, the surface of the sample 8) is expressed by the following formula (11) or formula ( 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 velocity v3, the velocity v2, the velocity v1, and the acceleration α by calculation, and the distance Ls and the distance L13 are known. The collision velocity vs at the moment of collision with the surface of the can be calculated.

  Next, a method for 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, the point Ps represents the surface of the sample 8, the point P <b> 1 represents the position of the first optical sensor 24, the point P <b> 2 represents the position of the second optical sensor 25, and the point P <b> 3 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 point P1, the point P2, and the point P3 in this order.

  The speed at which the indenter 2 bounced from the point Ps passes through the point P1 (that is, the first optical sensor 24) is v1 ′, and the indenter 2 bounced from the point Ps changes to the point P2 (that is, the second optical sensor 25). The speed at the time of passing is set as v2 ′, and the speed at which the indenter 2 bounced off from the point Ps passes through the point P3 (that is, the third photosensor 26) is set as 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 the point P1 to the point P2 is L12, the distance from the point P2 to the point P3 is L23, the distance from the point P1 to the point P3 is L13, and the distance from the point Ps to the point P3 is Ls. is there. The control unit 7 uses the method described with reference to FIG. 5 to determine the time T12 ′ until the indenter 2 bounced from the point Ps passes through the point P2 from the point P1 and the indenter 2 bounced from the point Ps from the point P2. A time T23 ′ until it passes through the point P3 and a time T13 ′ until the indenter 2 bounced off from the point Ps passes through the point P1 and the point P3 are measured.

The average speed v12 ′ between the point P1 and the point 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 expression (14), and the average speed v13 ′ can be calculated by the following expression (15).
v23 ′ = L23 / T23 ′ (14)
v13 ′ = L13 / T13 ′ (15)

Assuming that the indenter 2 is moving at an equal acceleration α ′, the relationship of the following equation (16) is established between the velocity v12 ′, the velocity v1 ′, and the velocity v2 ′.
v12 ′ = (v1 ′ + v2 ′) / 2 (16)
Similarly, the relationship of the following equation (17) is established for the velocity v23 ′, the velocity v2 ′, and the velocity v3 ′, and the relationship of the following equation (18) is established for the velocity v13 ′, the velocity v1 ′, and the velocity v3 ′. Holds.
v23 ′ = (v2 ′ + v3 ′) / 2 (17)
v13 ′ = (v1 ′ + v3 ′) / 2 (18)
From the equations (16), (17), and (18), the following equations (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)
Since the calculation unit 7 obtains the speed v12 ′, the speed v23 ′, and the speed v13 ′ by the above-described calculation formulas (13), (14), and (15), the calculation unit 7 calculates the formula (19) and the formula It is possible to calculate the speed v1 ′, the speed v2 ′, and the speed v3 ′ by (20) and Expression (21). As a result, the calculation unit 7 can calculate the acceleration α ′ of the indenter 2 bounced off from the point Ps from the equation (22).

Assuming that the indenter 2 is moving at a constant acceleration α ′, the repulsion speed vs ′ of the indenter 2 at the moment of rebounding 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. The repulsion speed vs ′ at the moment when 2 bounces off the surface of the sample 8 can be calculated.

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

  FIG. 14 is a schematic diagram showing a speed measurement unit 6 according to still another embodiment. The first light projecting unit 24a and the first light receiving unit 24b of the first light sensor 24 of the speed measuring unit 6 shown in FIG. 14 and the second light projecting unit 25a and the second light receiving unit 25b of the second light sensor 25 are: 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, and 23g extending from the side surface of the speed measurement main body 23 to the wall surface of the indenter passage 23a. Although only the through holes 23d and 23f are shown in FIG. 14, 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 passes through the first optical fiber 60 and irradiates the inside of the indenter passage 23a. Is done. The second optical fiber 61 extending from the first light receiving unit 24b is fitted into the through hole 23e, and the light emitted from the first light projecting unit 24a is received by the first light receiving unit 24b through the second optical fiber 61. . That is, the first light projecting unit 24 a of the first optical sensor 24 irradiates the inside of the indenter passage 23 a via the first optical fiber 60, and the first light receiving unit 24 b of the first optical sensor 24 is configured by the second optical fiber 61. The light applied to the inside of the indenter passage 23a is received. Similarly, a third optical fiber 62 extending from the second light projecting portion 25a is fitted into the through hole 23f, and the 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 unit 25b is fitted into the through hole 23g, and light emitted from the second light projecting unit 25a is received by the second light receiving unit 25b through the fourth optical fiber 63. . That is, the second light projecting unit 25 a of the second optical sensor 25 irradiates the inside of the indenter passage 23 a via the third optical fiber 62, and the second light receiving unit 25 b of the second optical sensor 25 is configured by the fourth optical fiber 63. The light applied to the inside of the indenter passage 23a is received.

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

  FIG. 15 is a schematic cross-sectional view of a coefficient of restitution measuring device 1 according to another embodiment. In the coefficient of restitution measuring instrument 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 injects the indenter 2 from the holder 3 toward the material 8 by the action of the air pressure. Since the configuration of the coefficient of restitution coefficient 1 of the present embodiment other than the use of the piston rod 19 is the same as the structure of the coefficient of restitution coefficient measuring apparatus 1 described so far, the redundant description is omitted.

  The piston rod 19 includes a cylindrical rod main body 19a, a cylindrical rod support portion 19b having a diameter larger than the diameter of the rod main body 19a, and a disk-shaped piston head 19e fixed to the front end of the rod main body 19a. And having. The rod body 19a is fixed to the rod support portion 19b by the rear end of the rod body 19a being embedded in the front end of the rod support portion 19b. The center axis of the rod body 19a coincides with the center axis of the body support portion 15b. The outer peripheral surface of the piston head 19 e slides with 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 urging spring 16 is inserted into a guide hole 19c formed in the rod support portion 19b. The guide hole 19c extends from the rear end to the front end of the rod support portion 19b, and the center axis of the guide hole 19c coincides with the center axis of the rod support portion 19b. A plug 18 that closes 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 this 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 on 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, since the length of the biasing spring 16 can be easily changed, the biasing force applied to the piston rod 19 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 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 biasing spring 16 is contracted, the biasing spring 16 applies a biasing force to the piston rod 19 to move the piston rod 19 toward the front of the injection mechanism 5. ing. The position of the piston rod 19 is the firing position of the piston rod 19.

  On the outer surface of the rod support portion 19b of the piston rod 19, an annular groove 19d extending along the circumferential direction of the rod support portion 19b is formed. The groove 19 d may be formed on a part of the outer surface of the rod support portion 19 b of the piston rod 19. When the piston rod 19 is in the firing position shown in FIG. 15, the firing lever 14 having a hook 14 a that can be engaged with the groove 19 d is fixed to the outer surface of the outer cylinder 12. The firing lever 14 has a through hole, and 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 into the through hole. Accordingly, the firing lever 14 is fixed to the outer cylinder 12 so as to be rotatable about the rotation shaft 17. As shown in FIG. 15, the outer cylinder 12 is formed with a through hole 12 c that penetrates the side surface of the outer cylinder 12, and the inner cylinder 13 penetrates the side surface of the inner cylinder 13, and the inner cylinder A first long hole 13 e extending along the longitudinal direction of 13 is formed. The hook 14 a of the firing lever 14 engages with the groove 19 d of the piston rod 19 through the through hole 12 c of the outer cylinder 12 and the first long hole 13 e of the inner cylinder 13.

  16 shows a state where 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. It is a schematic sectional drawing shown. 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. Movement is restricted. More specifically, when the front surface 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 limited. While the piston rod 19 moves from the firing position shown in FIG. 15 to the collision position where it collides with the stopper 20 shown in FIG. 16, the piston head 19e exists in a space extending from the piston head 19e to the indenter 2. Compress the air that you want. 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 19 e is limited by the stopper 20, the piston rod 19 does not contact the indenter 2. Thus, the indenter 2 may be injected toward the sample 8 with 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 that supports the rear end of the urging spring 16 forward or backward relative to the outer cylinder 12. Therefore, since the biasing force applied to the piston rod 19 by the biasing spring 16 can be adjusted, the collision speed of the indenter 2 injected by the air compressed by the piston rod 19 can be adjusted. When comparing the restitution coefficients of different samples, the material of the indenter 2 and the impact speed of the indenter 2 are preferably 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 conducted to confirm that the restitution coefficient measured using the restitution coefficient measuring machine 1 shown in FIG. The sample used for the experiment was a reference piece for a Shore hardness test having a cylindrical shape, and three reference pieces having a nominal hardness of Shore hardness 90, Shore hardness 60, and Shore hardness 30 were used. The restitution coefficient when these reference pieces were fixed to a steel anvil having a mass of 5.7 kg and the restitution coefficient 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 the 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 point Pa and the measurement point Pe are located at the outer periphery of the reference piece. The measurement point Pb is located between the measurement point Pa and the measurement point Pc, and the measurement point Pd is located between the measurement point Pc and the measurement point 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 urging 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 relative to the outer cylinder 12.

  FIG. 18A is a graph showing the restitution coefficient when the reference piece fixed to the steel anvil is measured by the restitution coefficient measuring machine 1, and FIG. 18B is the reference piece fixed to the wooden anvil. It is a graph which shows a restitution coefficient when measuring with the restitution coefficient measuring machine 1. FIG. As shown in FIGS. 18 (a) and 18 (b), the restitution coefficient measured by the repulsion velocity measuring instrument 1 of this embodiment is based on the case where the reference piece is fixed to the steel anvil and the reference piece on the wooden anvil. It was confirmed that there was no difference in the case of fixing and that it was not affected by the mass effect. It was also confirmed that the same coefficient of restitution was measured at all five measurement points Pa, Pb, Pc, Pd, and Pe.

  FIG. 19 (a) is a graph showing the shore hardness when a reference piece fixed to a steel anvil is measured with a D-type shore hardness tester, and FIG. 19 (b) is fixed to a wooden anvil. It is a graph which shows a shore hardness when the reference | standard piece measured with a D type Shore hardness tester. In the D-type shore hardness test, a hammer including a diamond indenter and an indenter support to which the indenter is fixed at the tip is dropped from a predetermined drop height onto a reference piece, and the rebound height when the hammer bounces back. Measure the thickness. The shore hardness is obtained by multiplying the ratio of the rebound height to the drop height by a predetermined proportional 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. 19 (a), when the reference piece was fixed to the steel anvil, a Shore hardness equal to the nominal Shore hardness of the reference piece was measured. On the other hand, as shown in FIG. 19B, 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 by the hammer is measured. It was confirmed that the shore hardness was affected. Further, it was confirmed that the measured Shore hardness gradually decreases from the central measurement point toward the peripheral measurement point.

  FIG. 20 (a) is a graph showing the leap hardness when a reference piece fixed to a steel anvil is measured with a leap hardness tester, and FIG. 20 (b) is a reference fixed to a 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 involves injecting an impactor body including an indenter and an indenter support with the indenter fixed to the tip toward the sample by a spring, the 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 when it collides. In the leap hardness test, the rebound velocity of the impact body relative to the collision velocity before the impact body collides with the sample is measured as the restitution coefficient, and the leap hardness is obtained by multiplying this restitution coefficient by a predetermined proportional constant. It is done. 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. 20A and 20B, 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 confirmed in the leap hardness test that the mass effect by the impact body affects the measured hardness. Further, it was confirmed that the measured leap hardness gradually decreased from the central measurement point toward the peripheral measurement point.

  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 indenter passage 23 a is formed in the speed measurement main body 23. You may have a lid through-hole connected to. FIG. 21A is a cross-sectional view showing an example of a lid 70 fixed to the front end of the speed measurement main body 23, and FIG. 21B is a view taken in the direction of the arrow I in FIG. Since the configuration of the present embodiment other than the lid 70 is the same as the configuration of the above-described embodiment, the overlapping description is 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 23 a of the speed measurement main body 23. The lid through-hole 71 has a cylindrical shape that extends from the front surface 70 a to the rear surface 70 b of the lid 70. 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 coefficient of restitution coefficient measuring machine 1.

  When the indenter 2 is ejected from the injection mechanism 5 with the front surface 70 a of the lid 70 in contact with the surface of the sample 8, the collision point where the indenter 2 collides with the surface of the sample 8 is the center axis of the lid through-hole 71 and the sample 8. May slightly deviate from the point of intersection with the surface. FIG. 22 is a schematic diagram showing an example of the distribution of the collision points S where 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. It is in a circle with radius Rs. It was confirmed by experiment 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 larger than at least 0.2 times the diameter d of the indenter 2 (that is, 0.2d <D), the indenter 2 ejected from the ejection mechanism 5 is applied to the lid 70. It can collide with the surface of the sample 8 without colliding.

  The lid through-hole 71 has a diameter D that is smaller than the diameter d of the indenter 2 so that the indenter 2 does not jump out of the coefficient of restitution coefficient measuring machine 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 injected from the injection 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 preferable to have. The diameter D of the lid through-hole 71 is preferably not less than 0.5 times the diameter d of the indenter 2, more preferably not less than 0.7 times the diameter d of the indenter 2, and more preferably the diameter of the indenter 2. It is 0.9 times or more of d.

  As shown in FIG. 21B, the lid 70 is fixed to the speed measurement main body 23 by three screws (fixing tools) 73. The lid 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 70 a 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 than three or more. As a fixture for fixing the lid 70 to the speed measurement main body 23, a hexagon bolt may be used instead of the screw 73.

  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 shutter mechanism 50 described above, it can be manufactured at a lower cost than the shutter mechanism 50. As a result, the manufacturing cost of the coefficient of restitution coefficient measuring machine 1 can be reduced. Furthermore, since the diameter D of the lid through-hole 71 is smaller than the diameter d of the indenter 2, the indenter 2 injected from the injection mechanism 5 is reliably prevented from jumping out of the speed measuring body 23. As a result, when the indenter 2 is ejected from the injection 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 instrument 1. There is no. Therefore, the safety of the operator can be improved. Furthermore, since the indenter 2 can be effectively prevented from being lost, the burden on the operator can be reduced.

  As shown in FIG. 21A, the speed measurement main body 23 may have an air vent hole 75 extending from the side surface of the speed measurement 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. If 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 repulsion speed of the indenter 2 may increase. By providing the air vent hole 75 in the speed measurement main body 23, the indenter passage 23 a 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. Accordingly, 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 the present embodiment, two air vent holes 75 are formed in the speed measurement main body 23, but the number of air vent holes 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 measuring body 1 through the air vent hole 75.

  FIG. 23 is a cross-sectional view showing a modified example 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 surface shape. The curvature radius rc of the wall surface 71 a of the lid through-hole 71 is constant from the front surface 70 a to the rear surface 70 b of the lid 70 and is larger than the curvature radius 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 (= d / 2) of the indenter 2.

Since the wall surface 71a of the lid through-hole 71 is configured by a curved surface having a constant curvature radius 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 in 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 coefficient of restitution coefficient measuring machine 1. Furthermore, the minimum diameter D _min of the lid through hole 71 is at least 0.2 times 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. Such a curved wall surface 71 a effectively prevents the indenter 2 ejected from the ejection mechanism 5 from colliding with the lid 70.

In order to reliably prevent the indenter 2 injected from the injection mechanism 5 from colliding with the lid 70, the minimum diameter D _min of the lid through hole 71 is preferably 0.5 times or more the diameter d of the indenter 2. More preferably, 0.7 times or more of the diameter d of the indenter 2, and more preferably 0.9 times or more of the diameter d of the indenter 2.

  FIG. 24 is a cross-sectional view showing another modified example 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. The lid through-hole 71 of the present embodiment has a cylindrical shape, but as shown in FIG. 23, the wall surface 71a of the lid through-hole 71 may be configured by a curved surface having a constant curvature radius rc. By fitting the stepped portion 70c of the lid 70 into the cylindrical portion 23h of the speed measuring body 23, the center axis of the lid through hole 71 can be easily matched with the center 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. The air vent hole 75 passes through the cylindrical portion 23 h 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 was conducted to measure the restitution coefficient using the restitution coefficient measuring machine 1 in which the lid 70 shown in FIG. 21 is 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 Shore hardness 95, Shore hardness 80, and Shore hardness 30 were used. Furthermore, using the same coefficient of restitution measuring instrument 1, the coefficient of restitution of the reference piece of the Rockwell hardness test having a cylindrical shape was also measured. In the experiment, the ratio of the diameter da (see FIG. 21) of the indenter passage 23a to the diameter d of the indenter 2 is changed, and the influence 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 restitution coefficient of the same reference | standard piece was measured using the restitution coefficient measuring machine 1 with which the shutter mechanism 50 was provided in the speed measurement main body 23, and the obtained measurement result was made into the reference value.

  The indenter 2 used in the first experiment is an alumina bearing ball, and the indenter 2 has a diameter d of 3 mm. The diameter D of the lid through hole 71 is 2.8 mm. Accordingly, 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 23 a has a diameter da that is 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 was 10 m / s.

  The indenter 2 used in the second experiment is an alumina bearing ball, and the indenter 2 has a diameter d of 3 mm. The diameter D of the lid through hole 71 is 2.8 mm. Accordingly, 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 23 a has a diameter da that is 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 was 10 m / s.

  The indenter 2 used in the third experiment is a bearing ball made of alumina, and the indenter 2 has a diameter d of 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 23 a 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 was 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 restitution coefficient measuring machine 1 in which the shutter mechanism 50 is provided in the speed measurement main 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 bearing ball 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 23 a has a diameter da that is 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 was 10 m / s.

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

  As is clear from Table 1, the restitution coefficient obtained in the first experiment, the second experiment, and the third experiment is almost the same as the restitution coefficient measured as the reference value. Therefore, the restitution coefficient measuring machine 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 is confirmed that even if the indenter 2 having a different diameter d is used, the same restitution coefficient can be obtained if the collision speed of the indenter 2 is made constant. It was.

  The restitution coefficient obtained in the second experiment is slightly lower than the restitution coefficient obtained in the first experiment and the restitution coefficient 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. The reason for this is considered that 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 that is 1.4 times or more the diameter d of the indenter 2. Also in the case of the coefficient of restitution coefficient measuring machine 1 in which the shutter mechanism 50 is provided in the speed measuring body 23, the indenter passage 23a preferably has a diameter da that is 1.4 times or more the diameter d of the indenter 2.

  Thus, according to the restitution coefficient measuring device 1 according to the above-described embodiment, the restitution coefficient can be measured without being affected by the mass effect generated by the conventional rebound hardness tester. Further, according to the coefficient of restitution measuring device 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, the mass effect is not affected. Tests can be performed in any direction.

  The coefficient of restitution measuring device 1 according to the above-described embodiment can be used as a hardness measuring device. That is, the hardness measuring machine includes a holder 3 that holds the spherical indenter 2, an injection mechanism 5 that injects the indenter 2 held by the holder 3 from the holder 3 toward the sample 8, and the indenter 2 that is applied to the sample 8. A speed measuring unit 6 that measures a collision speed that is a speed of the indenter 2 before the collision and a rebound speed that is a speed of the indenter 2 after the indenter 2 bounces off the sample 8. Furthermore, 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 restitution coefficient described above). Determine a hardness of 8.

  In this hardness measuring machine, as described above, the indenter 2 held by the holder 3 is injected from the holder 3 toward the sample by the injection 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 repulsion speed of the indenter 2 after the indenter 2 rebounds from 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 the ratio of the repulsion speed of the indenter 2 to the collision speed of the indenter 2 by a predetermined proportional constant (for example, 100 or 1000).

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

  The embodiment described above is described for the purpose of enabling the person having ordinary knowledge in the technical field to which the present invention belongs to implement 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. Accordingly, the present invention is not limited to the described embodiments, but is to be construed in the widest scope according to the technical idea defined by the claims.

DESCRIPTION OF SYMBOLS 1 Restitution coefficient measuring machine 2 Indenter 3 Holder 5 Injection mechanism 6 Speed measurement part 7 Calculation part 8 Sample 10 Display 12 Outer cylinder 13 Inner cylinder 14 Firing lever 15 Strike (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 passage sensor 25 2nd passage sensor 26 3rd passage sensor 30 1st operational amplifier 31 2nd operational amplifier 35 Conversion resistance 36 Conversion resistance 38 Comparator 40 Holder flange member 43 1st return spring 44 2nd return Spring 46 First guide rod 47 Second guide rod 48 Fastener 50 Shutter mechanism 51 Door 52 First opening / closing guide 53 Second opening / closing guide 54 Opening / closing rod 55 Link mechanism 56 First opening / closing shaft 57 Second opening / closing shaft 58 Opening / closing spring 60 First 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 Air vent hole

Claims (22)

A holder for holding a spherical indenter;
An injection mechanism for injecting the indenter held by the holder from the holder toward the sample;
A speed measuring unit that measures a collision speed that is a speed of the indenter before the indenter collides with the sample, and a rebound speed that is a speed of the indenter after the indenter bounces off the sample;
A restitution coefficient measuring machine, comprising: an arithmetic unit that calculates a restitution coefficient that is a ratio of the rebound speed to the collision speed. The holder has a cylindrical shape,
The front end of the holder is formed of a plurality of divided portions by forming a slit extending in parallel with the axis of the holder,
The coefficient of restitution coefficient measuring device according to claim 1, wherein the holder holds an outer peripheral surface of the indenter with the plurality of divided portions. The injection mechanism is
An inner cylinder in which a through hole is formed;
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 disposed between the outer cylinder and the indenter pushing member and contracting by the movement of the outer cylinder to apply a urging force to the indenter pushing member;
3. The coefficient of restitution coefficient measuring device according to claim 1, wherein the outer cylinder has a firing lever that can be engaged with a groove formed on an outer surface of the indenter pushing member. 4.   The coefficient of restitution coefficient measuring device according to claim 3, wherein the indenter pushing member is a striker that collides with the indenter held by the holder.   4. The coefficient of restitution coefficient measuring device 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 is
A speed measuring body having an indenter passage connected to the through hole;
4. The coefficient of restitution coefficient measuring device according to claim 3, further comprising a first passage sensor and a second passage sensor arranged along the indenter passage.   The coefficient of restitution coefficient measuring device according to claim 6, wherein the first passage sensor and the second passage sensor are optical sensors. The speed measuring 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 calculation unit includes a speed of the indenter passing between the first passage sensor and the second passage sensor, and a speed of the indenter passing between the second passage sensor and the third passage 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. Rebound coefficient measuring machine.   The coefficient of restitution coefficient measuring device according to claim 8, wherein the first passage sensor, the second passage sensor, and the third passage sensor are optical sensors. The speed measuring unit is
A speed measuring body having an indenter passage connected to the through hole;
A first passage sensor and a second passage sensor arranged in the arithmetic unit,
The first passage sensor is an optical sensor having a first light projecting 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 emitted inside the indenter passage via a second optical fiber,
The second light projecting unit emits light into the indenter passage through a third optical fiber, and the second light receiving unit receives light irradiated into the indenter passage through a fourth optical fiber. The coefficient of restitution coefficient measuring device according to claim 3 characterized by things. The speed measuring unit is
A speed measuring 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 point of the indenter in the first passage sensor and a detection end point of the indenter in the first passage sensor,
The said operation part calculates the said collision speed and the said repulsion speed by dividing the diameter of the said indenter by the time between the said detection start time and the said detection end time. Rebound coefficient measuring machine. The speed measurement unit includes a speed measurement 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 contacts the sample and closes the opening of the indenter passage when the speed measurement unit moves away from the sample. The coefficient of restitution measuring device according to claim 3, wherein The shutter mechanism is
A door disposed at the opening of the indenter passage;
An open / close bar whose tip protrudes from the speed measuring body;
The coefficient of restitution coefficient measuring device according to claim 12 provided with a link mechanism which changes movement of said opening-and-closing bar into opening-and-closing operation of said door. The speed measurement unit includes a speed measurement main body having an indenter passage connected to the through hole,
A lid having a lid through hole connected to the indenter passage is fixed to the front end of the speed measuring body,
4. The coefficient of restitution coefficient measuring device 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 coefficient measuring device 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 coefficient measuring device according to claim 14, wherein an air vent hole extending from a side surface of the speed measuring body to the indenter passage is formed in the speed measuring body.   The coefficient of restitution coefficient measuring device according to any one of claims 14 to 16, wherein the indenter passage has a diameter of 1.4 times or more the diameter of the indenter. The speed measurement unit includes a speed measurement 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;
The said holder advances the inside of the indenter channel | path when the said outer cylinder moves toward the said speed measurement part, The said indenter is hold | maintained in the indenter channel | path. Rebound coefficient measuring machine.   The coefficient of restitution coefficient measuring device according to any one of claims 1 to 18, wherein the indenter is made of ceramic.   The coefficient of restitution coefficient measuring device according to claim 19, wherein the indenter is a bearing ball made of alumina.   21. The coefficient of restitution coefficient measuring device according to claim 1, 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 from the holder toward the sample;
A speed measuring unit that measures a collision speed that is a speed of the indenter before the indenter collides with the sample, and a rebound speed that is a speed of the indenter after the indenter bounces off the sample;
A hardness measuring machine comprising: an arithmetic unit that determines the hardness of the sample based on a ratio of the repulsion speed to the collision speed.

Images