MAGNETIZING APPARATUS FOR MAGNETIC PARTICLE TESTING
OF WHEEL
[Technical Field]
[00011
The present invention relates to a magnetizing apparatus for
magnetic particle testing of a wheel. Particularly, the present invention
relates to a magnetizing apparatus for magnetic particle testing capable
of sufficiently securing magnetic flux density of a magnetic flux extending
in the circumferential direction of the wheel in space in the vicinity of
each side surface of the wheel, across the wheel from a hub to a rim
thereof.
[Background Art]
[00021
A magnetic particle testing method has been widely applied as a
conventional quality assurance technique for a railway wheel (referred to
simply as a wheel, hereinafter) including a hub, a plate, and a rim in
sequence from inward to outward in the radial direction of the wheel.
As a magnetic particle testing apparatus for magnetic particle
testing on a wheel, an apparatus disclosed in Patent Literature 1 has
been known, for example.
[00031
The magnetic particle testing apparatus disclosed in Patent
Literature 1, for the purpose of enabling to detect defects in any direction
of the entire surface of the wheel, includes: a through conductor inserted
into a bore (a hole of hub), and energized with direct current; and a pair
of magnetizing coils so disposed as to face respective opposite side
surfaces of the wheel, and energized with alternating current.
According to the magnetic particle testing apparatus disclosed in
Patent Literature 1, the energized through conductor generates a
magnetic flux extending in the circumferential direction of the wheel,
which enables radial defects radially extending around the bore to be
detected. In addition, each magnetizing coil generates a magnetic flux
extending in the radial direction of the wheel, which enables
circumferential defects concentrically extending around the bore to be
detected.
In Patent Literature 1, defect detectability is evaluated using an Atype
standard test specimen specified by JIS, and it is shown that
magnetic particle patterns have been clearly observed.
[00041
Meanwhile, in Europe, BN918277 and EN13262 are known as
manufacturing standards for a railway wheel. In BN918277, the
magnetic flux density in space in the vicinity of each side surface of a
wheel in a magnetized state is required to be 2.5 mT to 8.2 mT. In
EN13262, the magnetic flux density in space in the vicinity of each side
surface of a wheel in a magnetized state is required to be 4 mT or more.
[Citation List]
[Patent Literature]
[0005l
[Patent Literature 11 JP2003-344359A
[Summary of Invention]
[Technical Problem]
[00061
According to the magnetic particle testing apparatus disclosed in
Patent Literature 1, magnetic particle patterns formed on the standard
test specimen can be clearly observed, as described above.
Unfortunately, based on the studies conducted by the present
inventors prior to a sales promotion of wheels in Europe, it has been
found that the magnetic flux density of the magnetic flux in space in the
vicinity of each side surface of the wheel (particularly, the magnetic flux
density of the magnetic flux extending in the circumferential direction of
the wheel) does not satisfy the above European standards using the
magnetic particle testing apparatus disclosed in Patent Literature 1.
[00071
An object of the present invention, which has been made in view of
the conventional art, is to provide a magnetizing apparatus for magnetic
particle testing capable of sufficiently securing magnetic flux density of a
magnetic flux extending in the circumferential direction of a wheel in
space in the vicinity of each side surface of the wheel, across the wheel
from a hub to a rim thereof.
[Solution to Problem]
[00081
In order to solve the above-described problems, the present
invention provides a magnetizing apparatus for magnetic particle testing
of a wheel that includes a hub, a plate, and a rim in sequence from
inward to outward in a radial direction of the wheel, the apparatus
comprising: a conductor inserted through a bore; and a pair of auxiliary
conductors connected to respective opposite end portions of the conductor,
and so disposed as to face respective opposite side surfaces of the wheel,
and to extend from the hub to the rim outwardly in a radial direction of
the wheel, wherein the pair of auxiliary conductors and the conductor are
energized with alternating current.
[00091
The magnetizing apparatus for magnetic particle testing of a wheel
according to the present invention includes the conductor inserted
through the bore, and this conductor is energized with current so as to
generate a concentric magnetic flux around the central axis of the
conductor. This means that a magnetic flux extending in the
circumferential direction of the wheel is generated. The magnetic flux
density of the magnetic flux generated by the conductor becomes
gradually decreased apart from the conductor (that is, toward the rim).
The magnetizing apparatus for magnetic particle testing of a wheel
according to the present invention includes the pair of auxiliary
conductors connected to respective opposite end portions of the conductor,
and so disposed as to face the respective opposite side surfaces of the
wheel, and to extend outwardly in the radial direction of the wheel from
the hub to the rim. To be specific, one auxiliary conductor of the pair of
auxiliary conductors is connected to one end portion of the conductor, and
so disposed as to face one side surface of the wheel, and to extend
outwardly in the radial direction of the wheel. The other auxiliary
conductor of the pair of auxiliary conductors is connected to the other end
portion of the conductor, and so disposed as to face the other side surface
of the wheel, and to extend outwardly in the radial direction of the wheel.
The pair of auxiliary conductors are energized with current, thereby
generating a concentric magnetic flux around the central axis of each
auxiliary conductor. As described above, each auxiliary conductor is
connected to each end portion of the conductor, and extends outwardly in
the radial direction of the wheel, and thus the magnetic flux generated by
each auxiliary conductor extends in the circumferential direction of the
wheel, and the orientation of this magnetic flux (orientation of the
magnetic flux generated between each auxiliary conductor and each side
surface of the wheel) is the same as the orientation of the magnetic flux
generated by the conductor. Since each auxiliary conductor extends
from the hub to the rim of the wheel, the magnetic flux density of the
magnetic flux generated by each auxiliary conductor becomes
substantially uniform from the hub to the rim of the wheel. Hence, the
magnetic flux density of the magnetic flux extending in the
circumferential direction of the wheel, which is generated by the
conductor and each of the pair of auxiliary conductors, increases as
compared with the case of using the conductor alone, and more readily
becomes uniform from the hub to the rim of the wheel compared with the
case of using the conductor alone. By rotating the wheel in its
circumferential direction while magnetizing the wheel, the magnetic flux
density of the magnetic flux extending in the circumferential direction of
the wheel can be increased in the whole space in the vicinity of each side
surface of the wheel, and the magnetic flux density can be readily
uniform from the hub to the rim of the wheel.
In the magnetizing apparatus for magnetic particle testing of a
wheel, the pair of auxiliary conductors and the conductor are energized
with alternating current, so that the magnetic flux can be concentrated in
the vicinity of each side surface of the wheel due to the skin effect,
thereby enhancing the magnetic flux density in the space in the vicinity
of each side surface of the wheel.
As described above, according to the magnetizing apparatus for
magnetic particle testing of a wheel of the present invention, the
magnetic flux density of the magnetic flux extending in the
circumferential direction of the wheel in the space in the vicinity of each
side surface of the wheel can be sufficiently secured across the wheel from
the hub to the rim thereof.
Preferably, the magnetizing apparatus for magnetic particle testing
of a wheel further comprises a pair of magnetizing coils each of which
axial centerline direction faces each side surface of the wheel, the
magnetizing coils being energized with alternating current.
[00111
According to the above preferable configuration, the pair of
magnetizing coils energized with alternating current are arranged such
that the direction of the axial centerlines thereof face the respective
opposite side surfaces of the wheel. To be specific, one magnetizing coil
of the pair of magnetizing coils is arranged such that the direction of its
axial centerline faces one side surface of the wheel. The other
magnetizing coil of the pair of magnetizing coils is arranged such that the
direction of its axial centerline faces the other side surface of the wheel.
The magnetic flux extending in the radial direction of the wheel is
generated by this pair of magnetizing coils.
According to the above preferable configuration, the magnetic flux
extending in the circumferential direction of the wheel is generated by
the conductor and the pair of auxiliary conductors as described above,
and at the same time, the magnetic flux extending in the radial direction
of the wheel is generated by the pair of magnetizing coils; therefore, it is
possible to detect defects in any direction on each side surface of the
wheel.
[Advantageous Effects of Invention]
[00121
According to the present invention, it is possible to sufficiently
secure magnetic flux density of a magnetic flux extending in the
circumferential direction of a wheel in space in the vicinity of each side
surface of the wheel across the wheel from a hub to a rim thereof.
Accordingly, it is possible to satisfy Standards BN918277, EN13262 in
Europe by appropriately adjusting a current value of alternating current
and the like without excessively increasing this value.
[Brief Description of Drawings]
[00131
Figures 1A and 1B are schematic configuration diagrams showing a
wheel in a magnetized state using a magnetizing apparatus for magnetic
particle testing according to one embodiment of the present invention.
Figures 2A to 2C are diagrams showing an example of results from
measurement of magnetic flux density in space in the vicinity of each side
surface of the wheel using the magnetizing apparatus for magnetic
particle testing shown in Figure 1.
Figure 3 is a schematic diagram showing a standard test specimen
used for evaluating defect detectability using the magnetizing apparatus
for magnetic particle testing shown in Figure 1.
Figures 4A to 4D show examples of magnetic particle patterns
adhering on the standard test specimen shown in Figure 3.
[Description of Embodiment]
100 141
One embodiment of the present invention will be described with
reference to accompanying drawings, hereinafter.
Figures 1A and 1B are schematic configuration diagrams showing a
wheel in a magnetized state using a magnetizing apparatus for magnetic
particle testing according to one embodiment of the present invention.
Figure 1A is a front elevation viewed in a direction orthogonal to an axial
direction of the wheel. In Figure lA, the wheel is illustrated as its cross
section. Figure 1B is a front elevation viewed in the axial direction of
the wheel. In Figure lB, magnetizing coils and an AC power supplies
are not illustrated in the drawing.
As shown in Figures 1A and lB, the magnetizing apparatus for
magnetic particle testing (also referred to simply as the "magnetizing
apparatus", hereinafter) 100 according to the present embodiment is a
magnetizing apparatus for magnetic particle testing of the wheel 7
including a hub 71, a plate 72, and a rim 73 in sequence from inward to
outward in the radial direction of the wheel 7.
[00151
The magnetizing apparatus 100 includes a conductor 1, and a pair
of auxiliary conductors 2 (2A, 2B) connected to respective opposite end
portions of the conductor 1. The magnetizing apparatus 100 also
includes an AC power supply 4 connected to the respective auxiliary
conductors 2A, 2B.
[OOI~I
The conductor 1 is formed of copper, for example, and inserted
through a bore (hole through which an axle is inserted) 711 formed in the
hub 71 of the wheel 7. The conductor 1 of the present embodiment
includes a pair of cylindrical conductor pieces lA, lB, and each of the
conductor pieces lA, 1B is inserted into the bore 711 from each side
surface of the wheel 7 (side surface in an orthogonal direction to the axial
direction of the wheel 7) so that each opposite end portion of the
conductor pieces lA, 1B is put into a state of butting each other.
[00171
Alternating current is supplied to each of the auxiliary conductors
2A, 2B from the AC power supply 4, thereby energizing the conductor 1
with the alternating current.
The conductor 1 is energized with the alternating current, thereby
generating a magnetic flux B1 concentric around the central axis of the
conductor 1. This means that the magnetic flux B1 extending in the
circumferential direction of the wheel 7 is generated. The magnetic flux
density of the magnetic flux B1 generated by the conductor 1 becomes
gradually decreased apart from the conductor 1 (that is, toward the rim
73).
The magnetic flux B1 shown in Figure 1B indicates a magnetic flux
formed in a state where current flows from this side to the other side in
the perpendicular direction to the paper plane.
[00181
The pair of auxiliary conductors 2 are formed of copper, for example,
and connected to the respective opposite end portions of the conductor 1,
as aforementioned. Specifically, in the present embodiment, one
auxiliary conductor 2A is connected to an end portion (end portion not in
contact with the conductor piece 1B) of one conductor piece lA, and the
other auxiliary conductor 2B is connected to an end portion (end portion
not in contact with the conductor piece 1A) of the other conductor piece
1B. The pair of auxiliary conductors 2 of the present embodiment are
configured to be long tabular members, and so disposed as to face the
respective opposite side surfaces of the wheel 7, and to extend outwardly
in the radial direction of the wheel 7 from the hub 71 to the rim 73.
In the present embodiment, the auxiliary conductors 2A, 2B are
arranged substantially at the identical position when viewed from the
axial direction of the wheel 7, but the present invention is not limited to
this. For example, the auxiliary conductor 2A and the auxiliary
conductor 2B may be orthogonally arranged to each other when viewed
from the axial direction of the wheel 7, or the auxiliary conductor 2A and
the auxiliary conductor 2B may be arranged such that their extending
directions are opposite to each other.
100 191
Each end portion of the auxiliary conductors 2A, 2B is supplied
with alternating current from the AC power supply 4 so as to energize
each of the auxiliary conductors 2A, 2B with the alternating current.
Each of the auxiliary conductors 2A, 2B is energized with the alternating
current, thereby generating the magnetic flux B2 concentric around each
central axis of the auxiliary conductors 2A, 2B. As aforementioned, the
auxiliary conductors 2A, 2B are connected to the respective end portions
of the conductor 1, and also extend outwardly in the radial direction of
the wheel 7; therefore, the magnetic flux B2 generated by each of the
auxiliary conductors 2A, 2B extends in the circumferential direction of
the wheel 7, and the orientation of the magnetic flux B2 (orientation of
the magnetic flux B2 generated between each auxiliary conductor 2 and
each side surface of the wheel 7) is the same as the orientation of the
magnetic flux B1 generated by the conductor 1. Since each of the
auxiliary conductors 2A, 2B extends from the hub 71 to the rim 73 of the
wheel 7, the magnetic flux density of the magnetic flux B2 generated by
each of the auxiliary conductors 2A, 2B becomes substantially uniform
from the hub 71 to the rim 73 of the wheel 7.
The magnetic flux B2 shown in Figure 1B is illustrated as a
magnetic flux generated in a state where the current flows in the
auxiliary conductor 2A in the direction from the rim 73 to the hub 71
(state where the current flows to the conductor 1 in the direction from
this side to the other side in the perpendicular direction to the paper
plane).
Hence, the magnetic flux density of the magnetic flux (magnetic
flux formed by superimposing the magnetic fluxes B1, B2) extending in
the circumferential direction of the wheel 7, which is generated by the
conductor 1 and the pair of auxiliary conductors 2, increases as compared
with the case of using the conductor 1 alone, and more readily becomes
uniform from the hub 71 to the rim 73 of the wheel 7 compared with the
case of using the conductor 1 alone. By rotating the wheel 7 in its
circumferential direction while magnetizing the wheel 7, the magnetic
flux density of the magnetic flux extending in the circumferential
direction of the wheel 7 can be increased in the whole space in the vicinity
of each side surface of the wheel 7, and the magnetic flux density can be
readily uniform from the hub 71 to the rim 73 of the wheel 7.
E002 11
In the magnetizing apparatus 100, the pair of auxiliary conductors
2 and the conductor 1 are energized with alternating current, so that the
magnetic flux can be concentrated in the vicinity of each side surface of
the wheel 7 due to the skin effect, thereby enhancing the magnetic flux
density in the space in the vicinity of each side surface of the wheel 7.
E00221
As described above, according to the magnetizing apparatus 100 of
the present embodiment, the magnetic flux density of the magnetic flux
extending in the circumferential direction of the wheel 7 in the space in
the vicinity of each side surface of the wheel 7 can be sufficiently secured
across the wheel 7 from the hub 71 to the rim 73.
E00231
As a preferable configuration, the magnetizing apparatus 100
according to the present embodiment may include a pair of magnetizing
coils 3 (3A, 3B) arranged such that the direction of their axial centerlines
3N face the respective opposite side surfaces of the wheel 7. To be
specific, each of the magnetizing coils 3A, 3B is formed of a conducting
wire wound around the axial centerline 3N opposite to each side surface
of the wheel 7, and the axial centerline 3N is arranged to be substantially
coaxial with the axle of the wheel 7. The magnetizing apparatus 100
includes an AC power supply 5 connected to the magnetizing coil 3A, and
an AC power supply 6 connected to the magnetizing coil 3B.
Coo241
Alternating current is supplied to the magnetizing coil 3A from the
AC power supply 5 so as to energize the magnetizing coil 3A with the
alternating current, thereby generating a magnetic flux extending in the
radial direction of the wheel 7 (magnetic flux radially extending around
the axle of the wheel 7). In the same manner, alternating current is
supplied to the magnetizing coil 3B from the AC power supply 6 so as to
energize the magnetizing coil 3B with the alternating current, thereby
generating a magnetic flux extending in the radial direction of the wheel
According to the magnetizing apparatus 100 of the present
embodiment, as aforementioned, not only the magnetic flux extending in
the circumferential direction of the wheel 7 is generated by the conductor
1 and each of the pair of auxiliary conductors 2, but also the magnetic
flux extending in the radial direction of the wheel 7 is generated by each
of the pair of magnetizing coils 3; therefore, it is possible to detect defects
in any direction of the opposite side surfaces of the wheel 7.
[Example]
[0026]
Example of the present invention will be described, hereinafter.
A magnetic flux density measurement test was conducted in which
the wheel 7 was magnetized using the magnetizing apparatus 100 having
the aforementioned configuration, and during the magnetizing, the
magnetic flux density in the space in the vicinity of each side surface of
the wheel 7 (the magnetic flux density of the magnetic flux extending in
the circumferential direction of the wheel 7, and the magnetic flux
density of the magnetic flux extending in the radial direction of the wheel
7) was measured.
Specifically, alternating current was supplied to each of the
auxiliary conductors 2A, 2B from the AC power supply 4 so as to energize
the auxiliary conductors 2A, 2B and the conductor 1 with the alternating
current, and at this time, the magnetic flux density of the magnetic flux
extending in the circumferential direction of the wheel 7 was measured.
Subsequently, after the supply of the alternating current from the
AC power supply 4 was stopped, alternating current was supplied to the
magnetizing coil 3A from the AC power supply 5, and alternating current
was also supplied to the magnetizing coil 3B from the AC power supply 6
so as to energize the magnetizing coils 3A, 3B with the alternating
current, and at this time, the magnetic flux density of the magnetic flux
extending in the radial direction of the wheel 7 was measured.
[00271
As Comparative Example of the present invention, a magnetic flux
density measurement test was conducted in which the pair of auxiliary
conductors 2 were omitted in the same manner as the apparatus disclosed
in the above-mentioned Patent Literature 1, and direct current was
supplied to the conductor 1 from the DC power supply so as to energize
the conductor 1 with the direct current, and at this time, the magnetic
flux density of the magnetic flux extending in the circumferential
direction of the wheel 7 was measured.
[00281
In the measurement of the magnetic flux density in Example and
Comparative Example, Deutrometer of Nihon Matech Corporation was
used.
[00291
Figures 2A to 2C are diagrams showing an example of results from
measurement of magnetic flux density in the test as described above.
Figure 2A is a diagram for explaining regions (A, B, C) where the
magnetic flux density was measured. In Figure 2A, the region denoted
by a reference character A is a spatial region between the rim 73 of the
wheel 7 and the auxiliary conductor 2A. The region denoted by a
reference character B is a spatial region between the plate 72 (center of
the plate 72) of the wheel 7 and the auxiliary conductor 2A. The region
denoted by a reference character C is a spatial region between the hub 71
of the wheel 7 and the auxiliary conductor 2A. Figure 2B shows a result
from the measurement of the magnetic flux density of the magnetic flux
extending in the circumferential diction of the wheel 7 at the respective
regions shown in Figure 2A. Figure 2C shows a result from the
measurement of the magnetic flux density of the magnetic flux extending
in the radial diction of the wheel 7 at the respective regions shown in
Figure 2A.
E00301
As shown in Example of Figure 2B, it was found that, in the
magnetizing apparatus 100 according to the present embodiment,
through energizing of each auxiliary conductor 2 and the conductor 1 with
alternating current of 4500 A, the magnetic flux density of the magnetic
flux extending in the circumferential direction of the wheel 7 satisfies 2.5
mT to 8.2 mT specified by Standard BN918277 at all the region A (spatial
region in the vicinity of the rim 73), the region B (spatial region in the
vicinity of the plate 72), and the region C (spatial region in the vicinity of
the hub 71). It was also found that the magnetic flux density of the
magnetic flux extending in the circumferential direction of the wheel 7
satisfies 4 mT or more specified by Standard EN13262 at all the region A
to the region C.
C00311
To the contrary, as shown in Comparative Example of Figure 2B, in
the case of merely energizing the conductor 1 with direct current,
although the current value was set to be as great as 6000 A, the magnetic
flux density of the magnetic flux extending in the circumferential
direction of the wheel 7 satisfies Standard BN918277 only at the region C.
The magnetic flux density of the magnetic flux extending in the
circumferential direction of the wheel 7 does not satisfy Standard
EN13262 at any of the region A to the region C.
If it is possible to increase the current value used for energizing the
conductor 1 by approximately six times (36000 A), the magnetic flux
density of the magnetic flux extending in the circumferential direction of
the wheel 7 may satisfy Standard EN13262 at all the region A to the
region C. It is, however, very likely that Standard BN918277 is not
satisfied at the region C because the magnetic flux density becomes
excessively great.
E00321
As described above, according to the magnetizing apparatus 100 of
the present embodiment, the magnetic flux is generated by the conductor
1 and the pair of auxiliary conductors 2, so that the magnetic flux density
can be increased with smaller current compared with the case of using
the conductor 1 alone, and can be more readily uniform from the hub 71
to the rim compared with the case of using the conductor 1 alone.
Accordingly, it is possible to relatively easily satisfy Standard BN918277
and Standard EN13262.
E00331
As shown in Example 2 of Figure 2C, it was found that, using the
magnetizing coils 3 of five turns in the magnetizing apparatus 100
according to the present embodiment, and through energizing of the
magnetizing coils 3 with alternating current of 3000 A, the magnetic flux
density of the magnetic flux extending in the radial direction of the wheel
7 can satisfy 2.5 mT to 8.2 mT specified by Standard BN918277 at all the
region A, the region B, and the region C. At the region A, however, the
magnetic flux density of the magnetic flux extending in the radial
direction of the wheel 7 is slightly insufficient for 4 mT or more specified
by Standard EN13262.
E00341
For this reason, as shown in Example 1 of Figure 2C, the intensity
of magnetization was enhanced by increasing the number of turns of each
magnetizing coil 3 to seven from five; and as a result, it was found that
the magnetic flux density of the magnetic flux extending in the radial
direction of the wheel 7 satisfies both Standard BN918277 and Standard
EN13262 at all the region A to the region C.
E00351
While magnetizing the wheel 7 using the magnetizing apparatus
100 according to the present embodiment, a defect detectability
evaluation test was also conducted using a standard test specimen
specified by ASTM (ASTM CX-230) as shown in Figure 3. Figures 4A to
4D show examples of magnetic particle patterns adhering on the
standard test specimen, which were observed in this test.
[00361
According to the magnetizing apparatus 100 of the present
embodiment, as aforementioned, the magnetic flux density can be
increased with smaller current compared with the prior art using the
conductor 1 alone, and it is possible to obtain the magnetic flux density
more uniform from the hub 71 to the rim 73 compared with the prior art
using the conductor 1 alone. Accordingly, it was confirmed that
magnetic particle patterns as clear as, or more clear than those in the
prior art could be observed.
[Reference Signs List]
[00371
1 Conductor
lA, 1B Conductor piece
2, 2A, 2B Auxiliary Conductor
3, 3A, 3B Magnetizing coil
4, 5, 6AC power supply
7 Wheel
71 Hub
72 Plate
73 Rim
100 Magnetizing apparatus for magnetic particle testing
711 Bore

We claim:
[Claim 11
A magnetizing apparatus for magnetic particle testing of a wheel
that includes a hub, a plate, and a rim in sequence from inward to
outward in a radial direction of the wheel,
the apparatus comprising:
a conductor inserted through a bore; and
a pair of auxiliary conductors connected to respective opposite end
portions of the conductor, and so disposed as to face respective opposite
side surfaces of the wheel, and to extend from the hub to the rim
outwardly in a radial direction of the wheel,
wherein
the pair of auxiliary conductors and the conductor are energized
with alternating current.
[Claim 21
The magnetizing apparatus for magnetic particle testing of a wheel
according to claim 1, further comprising a pair of magnetizing coils each
of which axial centerline direction faces each side surface of the wheel,
the magnetizing coils being energized with alternating current.
Dated this 3rd day of April, 2014.