U.S. patent application number 09/777103 was filed with the patent office on 2001-08-02 for rebound-type hardness tester.
This patent application is currently assigned to KABUSHIKI KAISHA AKASHI. Invention is credited to Arai, Junichi, Minami, Yuichi, Sato, Yasunori.
Application Number | 20010010170 09/777103 |
Document ID | / |
Family ID | 27464084 |
Filed Date | 2001-08-02 |
United States Patent
Application |
20010010170 |
Kind Code |
A1 |
Sato, Yasunori ; et
al. |
August 2, 2001 |
REBOUND-TYPE HARDNESS TESTER
Abstract
A measurement cylinder having a passage for an indenter hammer
to go forward and backward formed therein is provided with two
light receiving holes a distance S apart. The times required for
the indenter hammer to go past the light receiving holes are
measured and, in accordance with the required times measured and
the distance S, the impacting velocity and the rebounding velocity
of the indenter hammer are detected, whereby it is made possible to
greatly improve the detecting accuracy of both the velocitys.
Inventors: |
Sato, Yasunori; (Zama-Shi,
JP) ; Arai, Junichi; (Zama-Shi, JP) ; Minami,
Yuichi; (Zama-Shi, JP) |
Correspondence
Address: |
Bruce L. Adams
Adams & Wilks
50 Broadway, 31st Floor
New York
NY
10004
US
|
Assignee: |
KABUSHIKI KAISHA AKASHI
|
Family ID: |
27464084 |
Appl. No.: |
09/777103 |
Filed: |
February 5, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09777103 |
Feb 5, 2001 |
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08964589 |
Nov 5, 1997 |
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6163952 |
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Current U.S.
Class: |
73/79 ; 73/12.01;
73/865.3 |
Current CPC
Class: |
G01N 3/52 20130101 |
Class at
Publication: |
73/79 ; 73/12.01;
73/865.3 |
International
Class: |
G01N 003/52 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 28, 1997 |
JP |
9-61787 |
Claims
What is claimed is:
1. A method of detecting velocitys of an indenter hammer in an
Equotip type hardness tester, including a measuring cylinder
constituting the body of said hardness tester and providing a
passage for said indenter hammer to go forward and backward, said
measuring cylinder having two light receiving holes formed therein
a distance S apart in the axial direction thereof, said method of
detecting velocitys of said indenter hammer in said Equotip type
hardness tester comprising the steps of: measuring the times
required for said indenter hammer to go past said two light
receiving holes; and detecting the velocitys of said indenter
hammer in accordance with said required times and said distance
S.
2. A method of detecting velocitys of an indenter hammer in an
Equotip type hardness tester according to claim 1, wherein said
required times are calculated by having a pulse counter, to which
timing pulses generated by a pulse generator are input, count the
number of said timing pulses from the moment of receipt of a signal
indicating that said indenter hammer passed by one light receiving
hole of said two light receiving holes to the moment of receipt of
a signal indicating that the same passed by the other light
receiving hole.
3. An Equotip type hardness tester comprising: a measuring cylinder
constituting the body of said hardness tester and providing a
passage for an indenter hammer to go forward and backward; a coil
spring incorporated in said body; an indenter hammer adapted to be
shot by the spring force of said coil spring toward a specimen; a
velocity sensor attached to said body for measuring the velocitys
of said indenter hammer immediately before impacting against said
specimen and immediately after the impaction; and a display unit
including a CPU receiving information of the velocitys of said
indenter hammer detected by said velocity sensor for calculating
hardness of said specimen and a display for displaying thereon the
hardness of said specimen calculated by said CPU; wherein said
velocity sensor is constituted of two light projecting holes formed
in the vicinity of the front end portion of said measuring cylinder
a distance S apart from each other in the axial direction of said
measuring cylinder and light receiving holes formed in the
positions corresponding to said light projecting holes, and,
further, light sources provided for each of said light projecting
holes and photodetector devices provided for each of said light
receiving holes.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The invention relates to an Equotip type hardness tester in
which an indenter hammer is caused to impact against a specimen and
the hardness of the specimen is measured from the ratio between the
velocitys of the indenter hammer before and after the
impaction.
[0003] 2. Description of the Related Art
[0004] A rebound type hardness tester, in which an indenter hammer
is caused to impact a specimen and the hardness of the specimen is
calculated from the ratio between the velocity of the indenter
hammer immediately before the impaction (impacting velocity) and
the velocity of the same immediately after the impaction
(rebounding velocity), is generally called an Equotip type hardness
tester and put to practical use.
[0005] Since the indenter hammer in the Equotip type hardness
tester is adapted to be shot by means of a coil spring, it is not
necessarily required, in hardness measurement, that the Equotip
type hardness tester is set in the position to keep the impacting
direction straight down. Namely, it is possible to carry out the
hardness measurement with the Equotip type hardness tester (the
body 1 formed of a cylindrical handle portion 11 and a measuring
cylinder 12 connected to it) tilted, i.e., keeping the impacting
direction, for example, in the horizontal direction, in an angle of
depression of 45.degree., in an angle of elevation of 45.degree.,
and in the direction straight up (the angle of inclination then
formed between the body 1 and the horizontal plane 010 is denoted
by 0) and with the front end of the measuring cylinder 12 abutting
on the specimen 01 as shown in FIG. 3. Thus, such an advantage is
obtained that hardness of the side face or bottom face of a
specimen can be freely measured.
[0006] The indenter hammer 3 is adapted to be discharged in the
axial direction of the body 1 guided by the cylindrical body 1.
Further, there are provided a permanent magnet within the indenter
hammer 3 and a velocity detecting coil 4 wound around the front end
portion of the measuring cylinder 12, and, by the movements of the
permanent magnet (i.e., the indenter hammer 3), electric currents
proportional to the impacting velocity and the rebounding velocity
are caused to flow through the velocity detecting coil 4. The
currents are converted into voltages by a voltage transformer 5
within a display unit 6, the voltages are input to a CPU 7 to
calculate the hardness, and the calculated value is displayed as
the Equotip hardness L of the specimen on a display 8. The Equotip
hardness L is defined by a later described expression (1).
[0007] The velocity impaction the specimen 01 of the indenter
hammer 3 when hardness is measured with the body 1 tilted is
different from its velocity produced when the body 1 is held in the
upright position. Therefore, it has so far been practiced to obtain
the correct hardness value by checking the value (hardness) of the
result obtained by the tilted measurement with a table (conversion
table) for angular correction. There is such a one put to practical
use that automatically performs the angular correction by means of
an incorporated CPU. Further, there is also such a one put to
practical use that automatically converts an obtained hardness
value into a standardized hardness value so far in use (e.g.,
Brinell, Vickers, Rockwell C, and Shore hardness) and displays the
hardness value.
[0008] The principle of measurement in the Equotip type hardness
tester will be described with reference to FIG. 4. Referring to
FIG. 4, reference numeral 3 denotes an indenter hammer and 01
denotes a specimen. The indenter hammer 3 is shot by a coil spring
(not shown) incorporated in the measuring cylinder 12 to impact the
specimen and then rebound from the same.
[0009] At this time, if friction and air resistance against the
indenter hammer 3 in motion is neglected and it is assumed that no
external force other than the gravitational force acts on the
indenter hammer 3 after it has been discharged, the hardness L of
the specimen 01 is defined by the following expression
L=(.vertline.V.sub.2.vertline./.vertline.V.sub.1.vertline.).times.1000
(1)
[0010] where
[0011] V.sub.1: impacting velocity of the indenter hammer,
[0012] V.sub.2: rebounding velocity of the indenter hammer.
[0013] In the conventional Equotip type hardness tester, detection
of the velocitys of the indenter hammer 3 (the impacting velocity
against and rebounding velocity from the specimen 01) is performed
by measuring voltages produced in the coil at the time when the
permanent magnet incorporated in the indenter hammer 3 passes by
the velocity detecting coil,
[0014] Generally speaking, the voltage change occurring in the
velocity detecting coil (in pulse waveform) varies with the
velocity at which the permanent magnet passes by the coil. Namely,
the slower the passing velocity of the permanent magnet, the duller
becomes the pulse waveform W (as shown by dotted lines in FIG. 5).
From this, a problem arises that accurate measurement results
cannot be obtained.
[0015] Further, there is also such a problem that when the specimen
is a magnetic body or it is magnetized or the environment is
magnetized, an accurate result of measurement cannot be obtained
due to the effect of such magnetism.
SUMMARY OF THE INVENTION
[0016] It is an object of the invention to provide a method of
detecting velocitys of the indenter hammer in an Equotip type
hardness tester whereby the above mentioned problems are solved and
an Equotip type hardness tester in which the aforesaid detecting
method is carried out.
[0017] As the means for solving the above problems, a method
according to the invention of detecting velocitys of an indenter
hammer in an Equotip type hardness tester, including a measuring
cylinder constituting the body of the hardness tester and providing
a passage for the indenter hammer to go forward and backward, the
measuring cylinder having two light receiving holes formed therein
a distance S apart in the axial direction thereof, comprises the
steps of measuring the times required for the indenter hammer to go
forward and backward past the two light receiving holes and
detecting the velocitys of the indenter hammer in accordance with
the required times and the distance S.
[0018] As the means for solving the above problems, the required
times are calculated by having a pulse counter, to which timing
pulses generated by a pulse generator are input, count the number
of the timing pulses from the moment of receipt of a signal
indicating that the indenter hammer passed by one light receiving
hole of the two light receiving holes to the moment of receipt of a
signal indicating that the same passed by the other light receiving
hole.
[0019] As the means for solving the above problems, an Equotip type
hardness tester according to the invention comprises a measuring
cylinder constituting the body of the hardness tester and providing
a passage for an indenter hammer to go forward and backward, a coil
spring incorporated in the body, an indenter hammer adapted to be
shot by the spring force of the coil spring toward a specimen, a
velocity sensor attached to the body for measuring the velocitys of
the indenter hammer immediately before impacting against the
specimen and immediately after the impaction, and a display unit
including a CPU receiving information of the velocitys of the
indenter hammer detected by the velocity sensor for calculating
hardness of the specimen and a display for displaying thereon the
hardness of the specimen calculated by the CPU, wherein the
velocity sensor is constituted of two light projecting holes formed
in the vicinity of the front end portion of the measuring cylinder
a distance S apart from each other in the axial direction of the
measuring cylinder and light receiving holes formed in the
positions corresponding to the light projecting holes, and,
further, light sources provided for each of the light projecting
holes and photodetector devices provided for each of the light
receiving holes.
[0020] In the invention, the indenter hammer, at the time of
measurement, passes by the two light receiving holes formed a
distance S apart in the axial direction of the measuring cylinder
in the order of the inner light receiving hole and the outer light
receiving hole in the impacting course, whereas it passes by them
in the order of the outer light receiving hole and the inner light
receiving hole in the rebounding course after impacting against a
specimen.
[0021] Hence, by measuring the time required for the indenter
hammer to pass by the light receiving holes in the impacting course
and the time required for the same to pass by the light receiving
holes in the rebounding course, the impacting velocity against and
the rebounding velocity from the specimen (face) of the indenter
hammer can be calculated in accordance with the measured times and
the distance between the light receiving holes.
[0022] The aforesaid times can be calculated by using a pulse
counter and by having numbers of timing pulses counted by the pulse
counter.
[0023] Further, since the indenter hammer velocity (detecting)
sensor is provided by that of a photoelectric type, it is made
possible to carry out the detection having the detecting accuracy
of the velocity of the indenter hammer unaffected by the indenter
hammer velocity.
[0024] Further, the measurement can be carried out unaffected by
magnetism.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] FIG. 1 is a diagram schematically showing a sensor portion
of velocitys of an indenter hammer in an Equotip type hardness
tester as an embodiment of the invention.
[0026] FIG. 2 is a circuit diagram of a velocity detector circuit
of the indenter hammer.
[0027] FIG. 3 is a diagram schematically showing a conventional
Equotip type hardness tester.
[0028] FIG. 4 is a diagram schematically showing the measuring
principle in the Equotip type hardness tester.
[0029] FIG. 5 is a pulse waveform in a conventional velocity
detector portion.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0030] A method of detecting velocitys of the indenter hammer in an
Equotip type hardness tester as an embodiment of the invention and
an Equotip type hardness tester in which the aforesaid detecting
method is carried out will be described with reference to the
accompanying drawings. FIG. 1 is a schematic diagram showing the
sensor portion of velocitys of the indenter hammer and FIG. 2 is a
circuit diagram of the detector circuit of the indenter hammer
velocitys. Reference numerals in FIG. 1 and FIG. 2 like those in
FIG. 3 and FIG. 4 denote virtually the same members.
[0031] In the embodiment of the described type, a set of light
projecting holes 1a and 2a constituting the sensor of the velocitys
of the indenter hammer 3 (impacting velocity against and rebounding
velocity from the specimen 01) are provided in the vicinity of the
front end portion of the measuring cylinder 12 a distance S apart
in the axial direction of the measuring cylinder 12 as shown in
FIG. 1.
[0032] Further, in the positions of the measuring cylinder 12
opposing the light projecting holes 1a and 2a, there are provided a
set of light receiving holes 1b and 2b the same distance S
apart.
[0033] The light projecting holes 1a and 2a are provided with light
sources 13 and 14 formed of a lens and a lamp and the light
receiving holes 1b and 2b are provided with photodetector devices
23 and 24 of a photodiode or the like. As the light source, other
than the lamp, that employing a semiconductor, such as a
light-emitting diode or a laser beam, may be used.
[0034] Further, at the portions close to the forefront of the
measuring cylinder 12, there are provided a light projecting hole
3a and a light receiving hole 3b opposing each other and a light
source 15 is provided for the light projecting hole 3a, while a
photodetector device 25 is provided for the light receiving hole
3b.
[0035] In the above described structure, at the time of
measurement, the indenter hammer 3 advances in the direction of the
arrow A and, when it reaches the position of the light projecting
hole 1a, the light beam being emitted from the light source 13 and
received by the photodetector device 23 through the light
projecting hole 1a and the light receiving hole 1b is blocked by
the indenter hammer 3.
[0036] When the indenter hammer 3 further advances in the direction
of the arrow A and reaches the position of the light projecting
hole 2a, the light beam being emitted from the light source 14 and
received by the photodetector device 24 through the light
projecting hole 2a and the light receiving hole 2b is blocked by
the indenter hammer 3.
[0037] The indenter hammer 3 further advances in the direction of
the arrow A, impacts against and rebounds from the specimen 01, and
moves in the direction opposite to the arrow A. Then, first, the
light beam being received by the photodetector device 24 is blocked
and, then, the light beam being received by the photodetector
device 23 is blocked.
[0038] The time T.sub.1 elapsed between the blocking of the light
to the photodetector device 23 and the blocking of the light to the
photodetector device 24 and the time T.sub.2 elapsed between the
blocking of the light to the photodetector device 24 and the
blocking of the light to the photodetector device 23 can be
measured by a later described electronic circuit (of FIG. 2) in
accordance with ON-OFF signals from the photodetector devices 23
and 24.
[0039] Meanwhile, the distance between the light projecting hole 1a
and the light projecting hole 2a, i.e., the distance between the
light receiving hole 1b and the light receiving hole 2b, is known
(to be S in the present embodiment). Hence, the impacting velocity
V.sub.1 of the indenter hammer 3 can be obtained by calculating the
ratio of S to T.sub.1 (S/T.sub.1), while the rebounding velocity
V.sub.2 of the indenter hammer 3 can be obtained by calculating the
ratio of S to T.sub.2(S/T.sub.2).
[0040] Now, the circuit for calculating the times T.sub.1 and
T.sub.2 in accordance with the ON-OFF signals from the
photodetector devices 23 and 24 will be described.
[0041] Referring to FIG. 2, reference numeral 21 denotes a pulse
counter for counting timing pulses 22a (clock pulses) generated in
a pulse generator 22.
[0042] The pulse counter 21 is adapted such that signals from the
photodetector devices 23, 24, and 25 are input thereto. In the
pulse counter 21, the number N.sub.1 of the timing pulses 22a from
the moment the signal indicating that the light to the
photodetector device 23 was blocked (an OFF signal from the
photodetector device 23) was input to the moment the signal
indicating that the light to the photodetector device 24 was
blocked (an OFF signal from the photodetector device 24) was input
and the number N.sub.2 of the timing pulses 22a from the moment an
OFF signal from the photodetector device 24 was input to the moment
an OFF signal from the photodetector device 23 was input are
respectively counted.
[0043] T.sub.1 and T.sub.2 are calculated in an operation device 26
in accordance with the numbers of pulses N.sub.1 and N.sub.2
counted by the pulse counter 21 and the frequency f of the timing
pulse 22a and, further, the impacting velocity V.sub.1 and the
rebounding velocity V.sub.2 of the indenter hammer 3 are calculated
in accordance with T.sub.1, T.sub.2, and the distance S between the
light receiving holes 1b and 2b.
[0044] The light projecting hole 3a and the light receiving hole
3b, as well as the light source 15 and the photodetector device 25,
are provided for confirming that the indenter hammer 3 has impacted
the specimen (face) and rebounded therefrom. Namely, when ON-OFF
signals from each of the photodetector devices have been received
by the pulse counter 21 in the order of an OFF signal from the
photodetector device 23.fwdarw.an OFF signal from the photodetector
device 24.fwdarw.an OFF signal from the photodetector device
25.fwdarw.an ON signal from the same, it is determined that the
indenter hammer 3 properly rebounded and, thereupon, the number of
pulses N.sub.1 and N.sub.2 are output from the pulse counter
21.
[0045] Thus, in the embodiment, since the indenter hammer velocity
(detecting) sensor is provided by that of a photoelectric type, it
is possible to carry out, the detection having the detecting
accuracy of the velocity of the indenter hammer unaffected by the
indenter hammer velocity and, further, the measurement can be
carried out without being affected by environmental magnetism or
magnetism in the specimen.
[0046] According to the Equotip type hardness tester of the
invention and the method of detecting velocitys of the indenter
hammer of the hardness tester, as described above in detail, the
following effects or advantages can be obtained:
[0047] (1) The time required for the indenter hammer to travel the
distance between the light receiving holes during its impacting
course and the time required for the same to travel the distance
between the light receiving holes during its rebounding course are
respectively measured and, in accordance with each of the measured
times and the distance between the light receiving holes, the
impacting velocity and rebounding velocity of the indenter hammer
against and from the specimen (face) can be calculated.
[0048] (2) The aforesaid times can be calculated by using a pulse
counter and by having numbers of timing pulses counted by the pulse
counter.
[0049] (3) Since the indenter hammer velocity (detecting) sensor is
provided by that of a photoelectric type, it is made possible to
carry out the detection having the detecting accuracy of the
velocity of the indenter hammer unaffected by the indenter hammer
velocity.
[0050] (4) The measurement can be carried out unaffected by
environmental magnetism or a magnetized specimen.
* * * * *