Patent Application
20050022377
1. Field of the Invention
This invention relates to a method for attaching two or more components and, more particularly, to such a method for ensuring orientation of three attached components.
2. Background Information
During the assembly of electrical conductors, an operation known as “spinning” is frequently used. During spinning, one conductor having a cylindrical projection is fitted into a circular hole of another conductor. This is followed by a peening operation that deforms some of the protruding material, thereby joining the two conductors together.
For example, during the manufacture of current transformer assemblies for circuit breaker trip units, an assembly including a load end conductor having a circular opening, a center conductor having two cylindrical projections, a current transformer, and a line end conductor having a circular opening is assembled. The relative orientation of the load end conductor with respect to the line end conductor is critical. First, one of the cylindrical projections of the center conductor is inserted through the circular opening of the load end conductor. Next, a first spinning or peening operation deforms that first cylindrical projection of the center conductor, in order to attach the center conductor and the load end conductor together. Then, the other of the cylindrical projections of the center conductor is inserted through the circular opening of the line end conductor, and the line end conductor and the load end conductor are suitably aligned. Next, a second spinning or peening operation deforms that second cylindrical projection of the center conductor, in order to attach the center conductor and the line end conductor together. Although the line and load end conductors are initially suitably aligned, the bonds between the cylindrical projections of the center conductor and the circular openings of the line and load end conductors may break during manufacture, installation, use or repair of the trip unit. Hence, the line and load end conductors may become misaligned, thereby requiring corrective repair.
There is a need, therefore, for an improved method for attaching two or more components.
There is also a need for an improved method for ensuring orientation of three attached components.
These needs and others are satisfied by the present invention which, in order to ensure reliable attachment and accurate orientation, employs a non-circular opening (e.g., a square hole) in each of two components, such as a load end conductor and a line end conductor. These conductors maintain their relative orientations after two spinning operations with another component, such as a center conductor having two projections. Although the two projections of the center conductor are preferably cylindrical, deformed material therefrom flows into the non-circular openings (e.g., into the corners of the square holes) during the two spinning operations. When this occurs, it is virtually impossible for the orientation of the outer load end and line end conductors to change position by rotation with respect to the inner center conductor.
As an aspect of the invention, a method of attaching at least two components comprises: employing a first component having a projection; employing a second component having a non-circular opening; passing the projection of the first component through the non-circular opening of the second component; and deforming the projection of the first component passing through the non-circular opening of the second component, in order to attach the first and second components together.
The method may further comprise: employing as the projection a first cylindrical projection; employing the first component further having a second cylindrical projection; employing a third component having a non-circular opening; passing the first cylindrical projection of the first component through the non-circular opening of the second component; passing the second cylindrical projection of the first component through the non-circular opening of the third component; and deforming the second cylindrical projection of the first component passing through the non-circular opening of the third component, in order to attach the first and third components together.
The third component may be aligned with respect to the second component before deforming the second cylindrical projection of the first component, in order to maintain the alignment after deforming the second cylindrical projection of the first component.
The components may include a center conductor and a load end conductor. The center conductor may be a tellurium bearing copper bar with a hard temper.
The method may further comprise: employing as the first component a center conductor having a first cylindrical projection and an opposite second cylindrical projection; employing as the second component a load end conductor; employing as a third component a line end conductor having a non-circular opening; passing the first cylindrical projection of the center conductor through the non-circular opening of the load end conductor; deforming the first cylindrical projection of the center conductor passing through the non-circular opening of the load end conductor, in order to attach the center conductor and the load end conductor together; passing the second cylindrical projection of the center conductor through the non-circular opening of the line end conductor; and deforming the second cylindrical projection of the center conductor passing through the non-circular opening of the line end conductor, in order to attach the center conductor and the line end conductor together.
The method may further comprise: employing a current transformer having an opening; and passing the center conductor through the opening of the current transformer before passing the second cylindrical projection of the center conductor through the non-circular opening of the line end conductor. The line end conductor may be aligned with respect to the load end conductor before deforming the second cylindrical projection of the center conductor, in order to maintain the alignment after deforming the second cylindrical projection of the center conductor. A first fixture may be employed to hold the center conductor before deforming the first cylindrical projection of the center conductor passing through the non-circular opening of the load end conductor. A second fixture may be employed to hold the center conductor and the load end conductor before deforming the second cylindrical projection of the center conductor passing through the non-circular opening of the line end conductor.
A full understanding of the invention can be gained from the following description of the preferred embodiments when read in conjunction with the accompanying drawings in which:
As employed herein, the term “deforming” may be accomplished, for example, by a “spinning” and/or a “peening” and/or an upsetting and/or a riveting operation.
As employed herein, the term “spinning” means, for example, orbital forming or radial forming.
As employed herein, the term “orbital forming” means, for example, displacing material at varying rates, when examined outward from a part's center.
As employed herein, the term “radial forming” means, for example, uniformly displacing material in three directions by kneading microscopic amounts of material radially outward, radially inward and tangentially overlapping. For example, radial forming may displace material uniformly at a constant speed, in an eleven-sided rosette pattern, in order to ensure uniform and consistent material displacement, thereby resulting in higher joint strength and superior surface finish.
As employed herein, the term “peening” means, for example, drawing, bending, impacting or flattening by, or as if by, hammering with a peen.
Referring to
A method of attaching the center conductor 4 and the load end conductor 6 includes: employing the center conductor 4 having the first cylindrical projection 8; employing the load end conductor 6 having the non-circular opening 12; passing the cylindrical projection 8 of the center conductor 4 through the non-circular opening 12 of the load end conductor 6 (as shown in
Referring to
Prior to performing a deforming operation on the second cylindrical projection 10 of the center conductor 4, the line side conductor 24 is positioned on the top 39 of the fixture 18, with the cylindrical projection 10 passing through the non-circular (e.g., square) opening 40 (as best shown in
After this alignment is performed by the fixture 18, the cylindrical projection 10 of center conductor 4 passing through the non-circular opening 40 of the line end conductor 24 is suitably deformed as shown by the partially deformed cylindrical projection 10′ of
As was indicated above, the line end conductor 24 is preferably aligned with respect to the load end conductor 6 before deforming the second cylindrical projection 10 of the center conductor 4, in order to maintain that alignment after the second deforming step. The first fixture 2 is employed to advantageously hold the center conductor 4 before deforming the first cylindrical projection 8 passing through the non-circular opening 12 of the load end conductor 6. The second fixture 18 is advantageously employed to hold the center conductor 4, the load end conductor 6 and the line end conductor 24 before deforming the second cylindrical projection 10 passing through the non-circular opening 40 of the line end conductor 24. Preferably, the conductors 6,24 are made of a suitable conductor, such as copper.
As shown in
Although conductors 6,24 having square openings 12,40 are shown in
Although exemplary conductors 4,6,24 and the current transformer 22 are shown, the invention is applicable to a wide range of such conductors and components, in order to support a wide range of trips units (not shown) for a wide range of circuit breaker frame sizes.
Although a cylindrical projection 8 is disclosed, it will be appreciated that a wide range of suitable projections (e.g., a substantially cylindrical projection; a projection having a suitable non-circular cross-section) may be employed.
The invention is further applicable to any application in which one or more conductor ends, or in which one or more mechanical attachment ends, are spun over or suitably deformed in a non-circular opening in order to ensure the relative orientation of two or more such components.
While specific embodiments of the invention have been described in detail, it will be appreciated by those skilled in the art that various modifications and alternatives to those details could be developed in light of the overall teachings of the disclosure. Accordingly, the particular arrangements disclosed are meant to be illustrative only and not limiting as to the scope of the invention which is to be given the full breadth of the claims appended and any and all equivalents thereof.
