Metal working – Method of mechanical manufacture – Electrical device making
Reexamination Certificate
1999-05-20
2001-07-03
Arbes, Carl J. (Department: 3729)
Metal working
Method of mechanical manufacture
Electrical device making
C029S825000, C029S826000, C029S601000
Reexamination Certificate
active
06253444
ABSTRACT:
BACKGROUND OF THE INVENTION
CROSS REFERENCE TO RELATED APPLICATION
This application claims priority of European Patent Application No. 98460015.5, which was filed on May 20, 1998.
1. Field of the Invention
The present invention relates to the manufacture of elbows for rectangular microwave guides.
Elbows for rectangular microwave guides are used to make directional changes of approximately 90 degrees or less, both in the plane E containing the electrical field and in the plane H containing the magnetic field.
2. Description of the Related Art
Several designs of elbows exist at present. A first type of elbow consists of a tube with a folded rectangular section to whose ends connection flanges are attached by soldering. A monolithic version of this type of elbow is manufactured by molding according to the method known as the lost-wax method. In both cases, the cost of manufacture is relatively high.
Another type of elbow is obtained from two complementary parts in each of which a half-tunnel equal to the entire length of the elbow is hollowed out from a plane connection face. The two half-tunnels are then placed so as to face each other and the two parts are joined by means of a plurality of screws. In this way, elbows are made with their tunnel, on the side external to the change in direction, having a transition face with a sequence of steps or levels. This design enables the use of simple and efficient machining technologies such as milling. However, the assembling of the two parts by screws may give rise to defects of coincidence between the two half-tunnels. These defects, however minute they might be, could have harmful effects. Furthermore the assembling screws, which must be sufficient in number to provide for a satisfactory link, take up a considerable volume of the material of the two parts and therefore hinder the miniaturization desired for most applications.
The invention is the result of research conducted on elbows for rectangular microwave guides with a view to achieving the following goals: simplicity of manufacture giving rise to an economical cost price, efficient reproducibility to enable mass production within tight tolerance values, high aptitude for miniaturization through the utmost elimination of the constraints of space requirement other than those inherent in the functional dimensions.
SUMMARY OF THE INVENTION
To this end, the invention consists of a method for the manufacture of an elbow for rectangular microwave waveguides, said elbow comprising an internal tunnel formed by two rectilinear sections that meet to define a dihedron on the internal side of the change in direction and, facing the peak of said dihedron, on the external side of the change in direction, a stepped transition face, wherein the method consists of the making, by machining in one block, from two faces of said block forming the connection ends of the elbow, of two rectangular boreholes that meet so that, at their meeting place, they define said dihedron on the internal side of the change in direction and said stepped transition face on the external side of the change in direction.
Provided that the steps of said transition face are straight steps, said boreholes can advantageously be made by the milling technique which provides a totally satisfactory degree of precision for the applications aimed at (working at frequencies of 10 to 20 GHz) and would remain sufficient well beyond these frequencies (at least up to 60 GHz).
Furthermore, in the monolithic elbow thus made, the totality of the volume of remaining material becomes available to receive fastening screws for the elements to which it will be connected thus enabling a maximum reduction of this volume of material and therefore of the total space requirement of the elbow.
REFERENCES:
patent: 3247574 (1966-04-01), Wirtz
patent: 4743915 (1988-05-01), Rammos et al.
patent: 4783663 (1988-11-01), Rammos et al.
patent: 4885839 (1989-12-01), Ben-Dov
patent: 4887346 (1989-12-01), Bertaian
patent: 5568160 (1996-10-01), Collins
Arbes Carl J.
Lucent Technologies - Inc.
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