Metal deforming – With use of control means energized in response to activator... – Metal deforming by use of roller or roller-like tool element
Patent
1989-11-07
1991-09-17
Ruehl, Charles A.
Metal deforming
With use of control means energized in response to activator...
Metal deforming by use of roller or roller-like tool element
73 82, G01N 330, G01M 700
Patent
active
050483200
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
1. Technical Field
The present invention relates to a method of and apparatus for inspecting the condition inside a structure or the like to be inspected, by applying an impact by a hammer to a surface portion of the structure or the like.
2. Background of the Invention
It is known that where an object involves a change in its internal structure, for example its thickness is not even or it includes a support or column inside, a change occurs in the sound it produces when its surface portion is hit. This is because, while the object undergoes vibration and produces sounds as it is subjected to impact force applications, the frequency and the waveform of the sound it generates undergo changes in accordance with changes in the rigidity and the density of the object having changes in its internal structure. This phenomenon takes place also where such as a peeled portion and a crack are present inside the object. Thus, it has been practiced in the art to make use of this phenomenon and inspect an internal defect in an object by applying an impact force to the object and examining the sounds then generated.
Generally, such impact-type inspections of objects are carried out by a skilled inspector in a manner such that the inspector applies striking at a variety of points on an object to be inspected, using a small-sized hammer exclusively for striking, such as a one called a test hammer and a one called a coin tap hammer, and the inspector exercising his or her acoustic organ, detects a change in the sounds then generated. Inspection methods of this type are widely relied on in for example the peeling or exfoliation inspection in honeycomb boards or plates, the peeling inspection of tiles, the crack generation inspection in concrete-placed objects or in various materials, the float inspection of decorative cement mortar on surfaces of concrete bodies, the locational detection of pillars, ribs, cores or the like present internal to or behind for example wall plates.
However, the above conventionally known impact-type inspection methods involve various shortcomings and difficulties such as (1) structural defects cannot or can hardly be detected unless the inspection is done by a skilled inspector; (2) in carrying out the inspection over a broad area, it becomes increasingly difficult to effect the detection of defects as the inspection is continued increasingly for a long period of time and as the inspector's nerves then become increasingly fatigued; (3) where an abnormal part is present relatively distant from a normal part in an object to be inspected, it tends to occur that the inspector cannot keep in memory a sound which the inspector has previously detected, when the inspector can no longer make the required judgment; (4) where an object to be inspected is located in a dangerous place and is not accessible, it is not feasible to conduct the inspection; (5) the inspection operation cannot be automated; and (6) the inspection cannot be carried out at noisy sites or places.
Then, it has already been devised in the art to mechanize those inspections which previously relied on manual operations, and there have been proposed impact-type inspection apparatus in which a hammer is mechanically driven, sounds generated from an object to be inspected are converted to electric signals by a microphone and subjected to a frequency analysis, and judgment of timbres is made by means of a speech recognition method to effect the inspection of abnormalities in the object.
As can be readily perceived from the foregoing, the conventional impact-type inspection apparatus are designed to effect discrimination between a normal part and an abnormal part in an object by a frequency analysis or a judgment of timbres relying on a speech or sound recognition means, so that the inspection operations have to be complex and, in addition, it is required to alter the standard or criterion for the judgment in carrying out inspections of different objects. Thus, there exists a demand for improving the known inspection methods and a
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Jyomuta Chihiro
Mitsuhashi Kunihiro
Nishikawa Hidetoshi
Oka Fujio
Mitsui Engineering & Shipbuilding Co. Ltd.
Ruehl Charles A.
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