Stock material or miscellaneous articles – Hollow or container type article
Reexamination Certificate
1997-05-01
2001-02-13
Heinrich, Samuel M. (Department: 1725)
Stock material or miscellaneous articles
Hollow or container type article
C228S184000, C376S272000
Reexamination Certificate
active
06187395
ABSTRACT:
The invention relates to a process for the production of a weld joint for at least three parts on a multiple stack, whereby parts are connected to each other via a commissure by means of a weldment.
The invention relates also to the application of said process in the manufacture of conveying and/or storage containers for burned-out nuclear fuel cassettes, consisting of a hollow cylindrical base body, ribs attached on its circumference which are radial to the cylindrical base body and a steel sleeve which encloses all of the ribs interlockingly from the outside.
In practice it is generally customary to produce a multiple stack of parts so that under the existing requirements, the parts to be connected by welding are connected to each other by several weldments which are preferably in form of fillet welds (see also Dubble, “Taschenbuch fuer Maschinenbau, 7
th
edition, page G 13).
Such a process requires that the multiple stack must be accessible in the vicinity of all of its fillets for the welder or for an automatic welding device. This is a disadvantage and limits the scope of applications for such weld joints.
This process has also the disadvantage that parts of different materials cannot be welded together, or can be welded together only under considerable limitations concerning the quality.
Optical control or verification of the quality of the weldment by means of appropriate instruments is often impossible. It is not possible to use such weld joints on objects which have to meet high safety standards.
Areas of application for such weld joints are, among others, conveying and storage containers for burned-out nuclear fuel cartridges.
These nuclear fuel cartridges are provided an essentially temporary wall. A tubular base body, the first part, has protruding ribs on its outside. This base body, together with its ribs is enclosed by a sleeve, the second part. This sleeve furthermore absorbs the radiation. It protects the resin body located between the ribs and the ribs in case of accident. The sleeve assists heat removal to the outside.
Such a conveying and storage container is shown among other things in DD Patent 131 445 and in DE-PS 40 32 343. The applicant and other manufacturers use an embodiment of the connection between the sleeve and the base body in which the sleeve consists of two half cups bent to fit exactly the outer diameter of the ribs which are braced against each other and connected to the base body.
With the usual size of these containers and the necessary wall thickness of the half cups of the sleeve it is not possible to establish direct material contact between the heads of all the ribs and the inner surface of the half cups.
In any case the heat transfer from the surface of the ribs to the sleeve is hindered considerably.
On the other hand, the missing material connection between the heads of the ribs and the sleeve results in a loss of strength which may have considerable and dangerous repercussions in case of accident.
In order to avoid these disadvantages it has been proposed in DE-P”40 32 343 to make the outer sleeve of individual segments. Each of these segments covers the space between two adjoining rib heads. The segments were welded to each other and to the heads of the ribs in form of multiple stack.
For further protection of the unreliably protecting weldment, angle profiles were added to the multiple stack and these covered the weldment on the multiple stack in addition.
The large number of weldments of considerable length and the great number of parts to be connected to each other resulted in high costs which were out of proportion with the effect obtained.
The tensions in the elements to be connected which were produced by welding were also disadvantageous.
The high requirements of heat elimination make it advisable to make the ribs on the base body of copper, for example. Copper is a superior heat conductor.
When using this material for example for the ribs, additional difficulties for which there are practically no solutions are produced in the production of the weldment.
DD 228 924 proposes a solution by which the additional outer sleeve for conveying and storage containers is dispensed with. This embodiment requires however a very thick-walled base body. The ribs are unprotected. No protected space for additional screening of radiation by the resin body is provided.
DE-PS 33 06 940 proposed that ribs be provided also on the inside of the sleeve to enter the intervals between the ribs on the base body.
This embodiment requires that the outer wall of the conveying container be formed by surfaces which make it possible to fit the ribs into each other during assembly.
It is furthermore a disadvantage that no or only very limited material contact exists between the ribs of the base body and the sleeve. Heat elimination to the outside and strength of such a container are insufficient.
The normally required quadrantal configuration of the conveying container has considerable disadvantages with respect to its strength in case of accident.
This leads to the object of the invention, consisting in proposing a weld joint which makes it possible to ensure a connection that can be produced efficiently, in particular on conveying containers for nuclear fuels which must meet the highest safety requirements and which consistent material contact between the parts of the weld joint, making it also possible to connect different materials on the multiple stack to each other, possess great strength in the connection of the multiple stack and
I. can be welded from one side of the multiple stack connection.
This object is attained by the invention through the process steps defined in claim
1
.
In this process the third part interlockingly inserted between the parts to be welded together is wedged in with such force by the shrinking forces of the weld joint and by the relatively high temperature that may occur in the plastic zone, so that a nearly material connection between the first and the third as well as between the second and the third part is ensured.
The strength of the connection between the first and the second part is ensured by the weldment itself. Occurring tensions do not affect this.
In this process the tensions within this connection are distributed and equalized.
These characteristics of the weld joint are also eminently suited for the production of the steel sleeve on conveying and/or storage containers for burned-out nuclear fuel cartridges.
The sleeve is composed of individual strips of which two strips in pairs are joined together into a multiple stack in the vicinity of a rib and are welded together according to the described process.
Because of their limited weight the individual strips are relatively easy to handle, can be placed with great precision with their inner shoulders of the recess on the ribs and can be connected in a known manner, manually or by means of automatic welding devices from the outside with one single weldment. The resin blocks can be installed before welding. Thereby possible cavities can be filled optimally and excellent protection from radiation is ensured. The thickness of the sleeve can be practically as desired, because a precise, coordinated bending of the sleeve over a great length is no longer necessary.
Optimal heat conduction to the outer surface of the sleeve is ensured by the almost material connection between the copper ribs and the steel sleeve. The above-mentioned connection also considerably increases the resistance of the conveying container to external mechanical influences of any kind and also meets the highest safety requirements.
The weldment itself can be controlled and if necessary retrofitted by the person controlling the welding process as well as by means of known inspection devices.
The error quotient in the manufacture of this extremely cost-intensive conveying container is furthermore significantly reduced.
REFERENCES:
patent: 3930166 (1975-12-01), Bochard
patent: 4292528 (1981-09-01), Shaffer et al.
patent: 4579274 (1986-04-01), Anspach et al.
patent: 4700863 (1987-10-01), Filippi
Botzem Werner
Canzler Hans-Jurgen
Hammer Heinz
Laug Reiner
Dority & Manning
GNB-Gesellschaft fur Nuklear-Behalter mbH
Heinrich Samuel M.
LandOfFree
Process for the production of a weld joint and conveying and... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Process for the production of a weld joint and conveying and..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for the production of a weld joint and conveying and... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2581766