Metal working – Method of mechanical manufacture – Electrical device making
Reexamination Certificate
2001-01-10
2003-03-25
Look, Edward K. (Department: 3745)
Metal working
Method of mechanical manufacture
Electrical device making
C191S0220DM
Reexamination Certificate
active
06536104
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of fabricating a longitudinal rail for supplying a mobile with electrical power.
2. Description of the Prior Art
Said rail includes two electrically conductive longitudinal components which are fastened together and have respective substantially constant cross sections and a common median longitudinal plane of symmetry, namely a mounting body adapted to be mounted on a support and a wear plate which is worn by said mobile,
said mounting body including, in mutually opposed positions in a transverse direction in said plane, a rigid longitudinal base for mounting it on said support and a longitudinal head for receiving said wear plate, which head is delimited in the direction away from said base in said transverse direction by an electrically conductive face straddling said plane and having a rebate in the direction away from said plane on respective opposite sides of said electrically conductive face,
said plate including a flat central strip for transmitting electrical power to said mobile, straddling said plane, having opposite said base in said transverse direction a contact face for said mobile and facing toward said base in said transverse direction an electrically conductive face bearing flat on said electrically conductive face of said body and two lateral rims on respective opposite sides of said plane and forming a projection toward said base in said transverse direction relative to said central strip, each of said rims having, facing toward said plane, an attachment face for attaching it to said body, which attachment face converges with said plane in the direction away from said central strip in said transverse direction to define a hook shape interengaged with a respective rebate so that said wear plate is fastened to said head of said mounting body by a mutual nesting effect.
Non-limiting examples of mobiles that can be supplied with electrical power include certain rail vehicles, such as metros, and some lifting or materials handling plant, such as travelling overhead cranes, moving along a particular trajectory along which are placed one or more lengths of a rail of the type indicated in the preamble, on the wear plate of which presses an electrical pick-up member such as a shoe carried by the mobile.
In this regard, a rail of the type to which the present invention relates can equally well be rectilinear or curved, and in the latter case, as will be obvious to a person skilled in the art, a median fiber of the rail is taken as the longitudinal reference and a surface defined by respective axes of symmetry of different sections of the rail perpendicular to its median fiber are taken as the median plane of symmetry.
Various designs of electrical power supply rails consisting of the association of a mounting body and a wear plate fastened together are well known in the art and widely used.
The mounting body is generally used to mount the rail on supports such as insulators and can itself be used to mount electrically insulative caps to protect against accidental contact with the power supply rail. Its cross section is generally much greater than that of the other component, and is determined on the one hand by the stiffness to be imparted to the rail and on the other hand by the current that is to flow in it. To reduce its weight, for a given cross section, the mounting body is generally made of aluminum or aluminum alloy.
The wear plate, which is adapted to cooperate with the electrical pick-up member carried by the mobile, is therefore made from stainless steel, for example, which is more resistant to wear than aluminum or aluminum alloy, although more dense, or of copper or brass. Its cross section is limited to that necessary to insure a particular minimum time of operation, at the end of which it is completely worn down, and its shape can vary according to the manner in which it is fastened to the mounting body.
One fastening method relying on clipping of the rims of the wear plate into rebates on the head of the mounting body, as indicated in the preamble, is used by the company BRECKNELL WILLIS, which employs an aluminum mounting body which is rigid, especially in the area of its head, and two stainless steel members, each of which corresponds to one half of the wear plate, i.e. to one of the parts thereof defined by the median plane of longitudinal symmetry. The electrically conductive faces of the mounting body, the central strip of the wear plate, and the contact face for the mobile are plane and perpendicular to the median longitudinal plane of symmetry. To assemble the wear plate to the mounting body, the two parts of the wear plate, which are initially independent of each other, are heated to a temperature higher than that of the mounting body and applied to the head thereof so that the corresponding respective half of the central strip is applied to a respective half of the electrically conductive face of the head and their rims are pressed against the corresponding respective rebates; when the two parts are perfectly face-to-face in this way, in the median longitudinal plane of symmetry, they are welded together and the assembly is then allowed to cool, whereby, because of the different coefficients of thermal expansion of stainless steel and aluminum, the wear plate grips the head of the mounting body and is fastened to it by this gripping effect alone.
However, the pressure applied by the stainless steel wear plate to the aluminum mounting body is afterwards closely dependent on temperature, and in the event of extremely low temperatures the pressure can be insufficient to retain the wear plate against movement in longitudinal translation on the mounting body and to insure an adequate quality of electrical conduction between the two components of the rail.
French patent FR-A-2 227 148 discloses a variant of the method indicated in the preamble including a succession of steps, the first of which consists of separately prefabricating:
said mounting body, conforming it so that said head is divided in said plane into two halves joined together by said base and delimiting between them a longitudinal slot open in the direction away from said base in said transverse direction, each of said two halves having opposite said base in said transverse direction a free end including a respective half of said electrically conductive face of said body and a respective rebate and being adapted to flex elastically relative to said base, in particular toward each other from a rest configuration in which said mounting body is prefabricated and as far as a maximum elastic flexing configuration, said two halves of said electrically conductive face of said body having an orientation relative to said plane such that they diverge from said base in said transverse direction toward said plane in said rest configuration, and
said wear plate, conforming it so that its rims define between them, perpendicularly to said plane, in an area of closest approach thereto in the direction away from the central strip in said transverse direction, a width less than the maximum width of said head perpendicularly to said plane between said halves of said electrically conductive face of said body and said rebates, in said rest configuration,
The wear plate and the mounting body are therefore made in one piece, and the next step consists of forcibly nesting the wear plate over the head of the mounting body, by virtue of elastic flexing of the wear plate such that its rims move apart and elastic flexing of the two halves of the head such that they move toward each other until they abut against each other, which defines a maximum elastic flexing configuration that the two halves of the head retain at the end of fabrication of the rail and in which the slot is closed.
A final step consists of permanently fastening the wear plate to the mounting body by spiking, riveting or welding the rims of the wear plate to the head of the mounting body.
The above document teaches respectively concave and convex V-s
Blakely & Sokoloff, Taylor & Zafman
Look Edward K.
McCoy Kimya N
Railtech International
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