Measuring and testing – Vibration – By mechanical waves
Reexamination Certificate
2000-10-30
2002-08-13
Williams, Hezron (Department: 2856)
Measuring and testing
Vibration
By mechanical waves
C073S644000, C073S627000
Reexamination Certificate
active
06431002
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an automatic ultrasonic flaw detector for detecting the inner flaw or defect of a molded material made of plastic, composite material or metal.
DESCRIPTION OF THE RELATED ART
For example, a molded material formed of composite material has an L-shaped, T-shaped or H-shaped cross section. The molded material is formed along the longitudinal direction.
In order to inspect any flaw or defect existing within the molded material, an ultrasonic flaw detecting technology is utilized.
The ultrasonic flaw detecting technology relates to propagating ultrasonic waves onto the surface of a molded material through medium such as water, converting the sonic wave reflected from the front surface of the molded material, the flaw existing within the material, and the back surface of the material into electric signals, and thereby detecting the inner conditions of the molded material.
According to another method (the through transmission method), the inner flaw may be detected by propagating ultrasonic waves from one side of the molded material placed under water, and receiving the transmitted sonic waves.
FIG. 9
shows the principle of an ultrasonic flaw detector utilizing the through transmission method.
Water W is filled inside a tank
10
, and a molded material P
1
, which is the object of inspection, is positioned inside the tank.
Ultrasonic wave V
1
is propagated toward the molded material P
1
from a transmission search unit
20
. A reception search unit
30
positioned to oppose to the unit
20
receives the transmitted sonic wave V
2
, and detects flaw.
According to such device, the transmission search unit
20
and the reception search unit
30
must be operated in synchronism. Moreover, the transmitted ultrasonic wave V
1
must be converged to concentrate the energy, and therefore, it is difficult to detect the flaw formed to a corner portion A
1
and the like of the molded material P
1
.
Therefore, a flaw detector utilizing a reflection method is provided.
Water W
1
is filled inside a tank
10
, and a molded material P
1
is placed inside the tank
10
. On one side wall of the tank
10
is positioned a plurality of search units
40
, which are for transmitting and receiving ultrasonic waves.
Similarly, a plurality of search units
50
are positioned to the bottom of the tank
10
, which are for transmitting and receiving ultrasonic waves.
FIG. 11
is an explanatory view showing the result of inspection performed according to the above flaw detector.
The ultrasonic wave V
1
transmitted from the search unit
40
is reflected by the front surface S
1
and the back surface b
1
of the molded material P
1
, and a waveform as shown in
FIG. 11
is drawn on an oscilloscope O
1
.
In advance, a normal (good) back surface reflection level L
1
is set within the range of a gate G
1
as the back surface range width, using a sample.
FIG. 11
(A) shows the reflected wave of the solid (good) portion of the molded material P
1
. The reflected wave EB
1
reflected by the back surface B
1
exists above the set level L
1
within the gate G
1
, and therefore, the inspected portion is determined to be acceptable.
FIG. 11
(B) shows the state where a void H
1
so-called porosity is formed within the molded material P
1
. When such a void H
1
exists, the reflected wave EB
1
is damped, and the level will not reach the set level L
1
. As a result, the inspected portion is determined to be unacceptable.
FIG. 11
(C) shows the state where an exfoliated portion F
1
so-called a delamination exists near the back surface B
1
of the molded material P
1
. If the molded material P
1
is manufactured by press forming plural sheets of laminated FRP films, delamination portion F
1
is likely to appear within the material.
When such defect exists, however, the reflected wave EF
1
from the delamination portion F
1
may exceed the set level L
1
within the gate portion G
1
set to the position corresponding to the back surface B
1
, and the inspected portion may be determined to be acceptable.
Especially when the thickness of the molded material is small, such problem occurs.
SUMMARY OF THE INVENTION
Therefore, the present invention aims at solving the above problems of the prior art by providing a device capable of detecting the flaw existing within the object molded material correctly, even if the molded material is formed of composite material.
The automatic ultrasonic flaw detector according to the present invention comprises, as basic means, a flaw detection chamber filled with water and having an opening portion through which a molded material being the object of inspection travels; an ultrasonic search unit positioned within the chamber to oppose to one surface of an object portion of inspection of the molded material; an ultrasonic reflector plate positioned to oppose to said ultrasonic search unit and to have a predetermined distance from the other surface of said object portion of inspection; and an inspecting means for comparing the reflected signal of ultrasonic waves with the signal from a solid portion.
The detector further comprises rollers for gripping and sending the molded material into the flaw detection chamber, and bellows equipped to the opening portion of the flaw detection chamber through which the molded material travels, so that water within the chamber is prevented from leaking.
The reflector plates are formed as a unit removably placed within the flaw detection chamber, and the unit of reflector plates is divided into two parts with its boundary set along the opening portion of the flaw detection chamber.
REFERENCES:
patent: 3400363 (1968-09-01), Silverman
patent: 3828609 (1974-08-01), Furon et al.
patent: 4489611 (1984-12-01), Zimmermann et al.
patent: 4644510 (1987-02-01), Fujii
patent: 4677842 (1987-07-01), Piche
patent: 4848159 (1989-07-01), Kennedy et al.
patent: 5629865 (1997-05-01), Roth
patent: 6089095 (2000-07-01), Yang et al.
Armstrong Westerman & Hattori, LLP
Jamco Corporation
Miller Rose M.
Williams Hezron
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