X-ray or gamma ray systems or devices – Specific application – Absorption
Reexamination Certificate
1999-09-17
2001-04-17
Bruce, David V. (Department: 2882)
X-ray or gamma ray systems or devices
Specific application
Absorption
C378S004000
Reexamination Certificate
active
06219402
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field of the Invention
The invention relates to a method for testing an object, in which a sectional image of the object is generated in at least a partial segment of the object by means of an X-ray computer tomographer. In the method, the object is clamped in a holding device, with which at least the partial segment is brought, in direction extending transversely to the segment, into a beam path between an X-rag source and an X-ray detector of the computer tomographer; then, the object and the holding device are pivoted, in at least one angular region, and relative to the X-ray source with the X-ray detector, about a first axis that extends through the partial segment and the beam path, with the partial segment remaining in the beam path. In specific angular increments, the X-ray detector generates a radiogram, and a cross-sectional image through the partial segment is reconstructed from these radiograms. The invention further relates to a device for executing the method.
2. Prior Art
A device of this type is known from EP 0 471 096 A1. The subject is a rim-mounted tire that is received at its end face in a holding device, which can travel on an adjusting sliding element on a pivoting device such that the pivoting axis of the pivoting device approximately axially passes through a tire cross section.
The beam fan of the X-ray device passes through the tire perpendicular to the pivoting axis; a holding arm of the beam receiver is positioned close to the tire and, depending on the pivoting position, is located in the open space of the rim or extends through it. The X-ray device is held on a sliding element that can be displaced perpendicular to the beam path and perpendicular to the pivoting axis of the tire, so a plurality of individual images of the one tire cross section can be generated corresponding to the different pivoting positions and the different displacement positions, and used in a cross-sectional representation. Further cross sections of the tire can only be obtained after the tire has been unclamped and fixed in a different angular position.
A computer tomographer that is particularly provided for testing cross sections of rim-mounted tires is known from EP 0 652 433 A. The tire is held in a holder about a pivoting axis perpendicular to the beam fan of an X-ray device. The tire can be displaced, in a sliding element, perpendicular to the pivoting axis and parallel to the tire plane, so the pivoting axis can be shifted into the one or the other of the two tire cross sections through which the beam fan passes, corresponding to the displacement positions. It is not possible to execute and allaround testing of the tire.
Numerous receptacles, such as sheet-metal boxes or the like, have some sort of folded-seam connections. For example, the lids or bottoms of tin cans are often connected to the jacket part through a folded-seam connection. Different forms of folded-seam connections are selected depending on the material and stress of the package. For sealing purposes, a sealing element may also be incorporated into a folded-seam connection.
The quality of a folded-seam connection depends on, among other things, the correct position of the material layers in the fold. At the present time, the quality can only be tested in a seal test (pressure test), mechanical stress tests or an external geometrical check of the dimensions. Cutting open the fold and removing and examining segments from the fold at defined or critical locations is the only way to obtain information about the correct material connection inside the fold. This is a destructive test, so, of course, only sample testing can be performed on packages in this method. Furthermore, the mechanical cutting open of the folded-seam connection can mechanically influence the sectional surface to be examined such that the original state of the folded-seam connection is no longer apparent. The test result is therefore skewed.
Because numerous boundary layers are present in a folded-seam connection, it is not possible to employ ultrasound methods or the like in testing.
OBJECT AND SUMMARY OF THE INVENTION
It is the object of the present invention to make the method described at the outset applicable for testing a folded-seam connection of a receptacle, and to provide a device for executing this method, with which it is possible to obtain information about the completely-correct material connection within a circumferential fold without destroying the object. This method and this device are further intended to operate quickly and inexpensively.
This object is accomplished in that the object is a receptacle having a folded-seam connection between a lid and/or a bottom and a jacket; to generate a sectional image through this folded-seam connection in the radial direction, the holding device is pivoted about the first axis; to generate at least one further sectional image through at lest one further partial segment of the folded-seam connection, the receptacle is rotated along its circumference in the holding device until the further partial segment of the folded-seam connection is located in the beam path (S), and the holding device and the receptacle are then pivoted about the first axis again to generate an image.
With the use of an X-ray computer tomographer to examine the folded-seam connection, a precise profile contour of a multi-layer folded-seam connection can be obtained, so material of varying density, such as metal, a hollow space, a plastic seal, another metal layer, etc., can be superposed. In this way, the same sectional images are obtained as in the cutting open of the fold, without the receptacle being destroyed or the sectional surface being influenced.
For the test, at least a partial segment of a folded-seam connection of the receptacle is brought, in a direction transverse to the longitudinal direction of the fold, into a beam path between an X-ray source and an X-ray detector of a computer tomographer. Then, the receptacle and/or the X-ray source with the X-ray detector are rotated relative to one another such that the partial segment of the folded-seam connection is rotated in at least one angular region about a first axis extending through the beam path. The partial segment of the folded-seam connection remains in the beam path. In specific angular increments, the X-ray detector generates a radiogram, and a cross-sectional image through the partial segment of the folded-seam connection is reconstructed from these X-ray images.
For executing the method, the device has at least one computer-tomography device (CT device) that has at least one X-ray source and one X-ray detector. The device further includes at least one holding device for a receptacle having a folded-seam connection; the holding device holds the receptacle such that the folded-seam connection is located, at least on the partial segment, in the beam path between the X-ray source and the X-ray detector, and the holding device and/or the receptacle can be rotated relative to the X-ray source with the X-ray detector such that the partial segment of the folded-seam connection is rotated, in at least one angular region, about a first axis of rotation that extends through the beam path; the partial segment of the folded-seam connection remains in the beam path.
Usually, a line detector that extends in the desired sectional-image plane is used as the X-ray detector. The detector can, however, also be displaced along a path within the sectional-image plane, and travel along the path, in order to generate a radiogram. In this case, “beam path” refers to the entire beam path between the X-ray source and the detectable detector range. The central axis between the X-ray source and the central point of the path along which the detector can travel would then be the optical axis of this system.
The first axis about which the partial segment of the folded-seam connection is rotated preferably extends directly through the partial segment of the folded-seam connection and, preferably, also exactly perpendicular through
Browdy & Neimark
Bruce David V.
Dunn Drew A.
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