EP0328946A2

EP0328946A2 - Permanent electric contact applicable to the web of rails and the like

Info

Publication number: EP0328946A2
Application number: EP89101779A
Authority: EP
Inventors: Ennio Peroni
Original assignee: Cembre SpA
Current assignee: Cembre SpA
Priority date: 1988-02-18
Filing date: 1989-02-02
Publication date: 1989-08-23
Also published as: IT1215911B; DE8901317U1; EP0328946A3; IT8819456A0

Abstract

The present invention relates to a permanent electric contact applicable to the web of rails and the like which comprises a bush (1) of electrically conducting material having a cylindrical stem (2) insertable in a hole (3) provided on the web (4) of a rail and the like, and a flanged head (5) engageable in abutment with the portion of the web surrounding said hole. Said bush has a through axial hole (l0) in which a punch (15) can be inserted, said punch being adapted to radially expand the cylindrical stem (2) and stably couple it in said hole (3).

Description

The present invention relates to a permanent electric contact applicable to the web of rails and the like.
As is known, a currently strongly felt problem is to provide permanent electric contacts, for example to electrically connect a portion of rail to the induction box, which allow optimum contact characteristics.
Currently adopted solutions, besides being very complicated from a constructive point of view, have the severe disadvantage of producing considerable contact resistances, since a tight coupling between the actual electric contact and the rail cannot be achieved.
A whole range of disadvantageous electric phenomena can consequently arise, mostly due to contact resistances, severely compromising the electric contact.
The aim of the invention is indeed to eliminate the previously described disadvantages by providing a permanent electric contact applicable to the web of rails and the like which tightly and stably couples the electric contact to the hole normally provided on the web of the rail, reducing contact resistances.
Within the scope of the above described aim, a particular object of the invention is to provide an electric contact in which the connection of the electric conductor can be performed without producing disadvantageous mechanical stresses on the electric contact.
Still another object of the present invention is to provide a permanent electric contact which by virtue of its peculiar constructive and applicative characteristics is capable of giving the greatest assurances of reliability and safety in use.
Not least object of the present invention is to provide an electric contact which is easily obtainable starting from elements and materials commonly available on the market and is advantageous from a merely economical point of view.
The above described aim, as well as the objects mentioned and others which will become apparent hereinafter, are achieved by a permanent electric contact applicable to the web of rails and the like, according to the invention, as defined in the appended claims.
The characteristics and advantages will become apparent from the description of a preferred but not exclusive embodiment of a permanent electric contact applicable to the web of rails and the like, illustrated only by way of non-limitative example in the accompanying drawings, wherein:

figure 1 is a perspective view of the bush of electrically conducting material;
figure 2 is a schematic sectional view of the bush applied to the inside of the web of a rail;
figure 3 illustrates the step of radial expansion of the bush, obtained by means of a gauged punch; and
figure 4 is a schematic sectional view of the electric contact to which the locking bolt of a wire terminal is applied to connect an electric conductor to the rail.

With reference to the above described figures, the permanent electric contact applicable to the web of rails and the like, according to the invention, comprises a bush, indicated as a whole by the reference numeral 1, which is made of electrically conducting material such as copper, cadmium plated copper, aluminum and alloys thereof and the like.
Said bush 1 has a cylindrical stem 2 which is insertable in a hole 3 provided on the web 4 of a rail and the like.
The cylindrical stem 2 extends from a head 5 which is intended to abut against the portion of the web 4 which surrounds the hole 3.
The bush 1 has a through axial hole, indicated as a whole by the reference numeral 10, which advantageously has a widened portion 11 in the portion substantially corresponding to the head 5; said widened portion is studied specifically to avoid unwanted deformations of said head during the operations which will be described hereinafter and to introduce lubricants and the like.
The bush 1 is locked on the web 4 by means of a gauged punch, indicated by the reference numeral 15, having at one end a threaded portion 16 arranged at the end of a cylindrical portion 17 which precedes a truncated-cone expansion 18.
In practical use, after applying the bush 1 in the hole 3 of the web 4 of the rail, the gauged punch 15 is inserted in the bush from the side of the latter having the head 5, causing the end with the threaded portion 16 to protrude.
An appropriate threaded seat of a hydraulic jack then engages the threaded portion l6 so that said jack, actuated by an oleodynamic pump, may mechanically pull the punch 15.
By passing through the axial hole 10, the punch causes a radial expansion of the bush, which expansion recovers the difference between the outer diameter of the bush and the hole of the rail, stably coupling said bush and said rail in tight contact.
The material displaced by the gauged punch which is in excess with respect to the material needed to fill the hole 3 is subject to an axial extrusion and protrudes from the hole 3 in an axial direction; this creates a further element for coupling the deformed bush on said rail.
This radial expansion allows a permanent and tight electric contact between the bush 1 and the hole 3 of the rail, while the gauged hole which forms axially inside the bush 1 allows to removably couple electric conductors fitted with a terminal by bolting.
More in detail, a bolt 20 is insertable in the gauged hole and engages, at its free end, with a nut 21 which presses on a concave or cup washer 23 with a split washer 22 possibly interposed; on its face directed towards the rail, said concave washer has a cylindrical cavity 24 which accomodates in its interior the protruding part of the bush and allows to transfer the pressure produced by the bolt to the rail without altering the electric contact between said bush and said rail.
The head 20a retains a wire terminal 26 against the head 5 of the bush, with a flat washer 25 interposed, thus providing a stable and precise electric connection.
From the above it can thus be observed that the invention achieves the intended aim and objects, and in particular the fact is stressed that an electric contact is provided which, by expanding radially, provides a tight contact between the bush and the hole, this contact being furthermore stable as it is obtained by forcing the gauged punch 15 inside the hole 10.
The presence of the concave washer furthermore allows an optimum mechanical coupling, since all the stresses exerted by the bolt discharge onto the rail without affecting the electric contact provided by means of the bush 1.
The invention thus conceived is susceptible to numerous modifications and variations, all of which are within the scope of the inventive concept.
Furthermore, all the details may be replaced with other technically equivalent elements.
In practice, the materials employed, so long as compatible with the specific use, as well as the contingent shapes and dimensions, may be any according to the requirements.
Where technical features mentioned in any claim are followed by reference signs, those reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly such reference signs do not have any limiting effect on the scope of each element identified by way of example by such reference signs.

Claims

1 . A permanent electric contact applicable to the web of rails and the like, characterized in that it comprises a bush (1) of electrically conducting material having a cylindrical stem (2) insertable in a hole (3) provided on the web (4) of a rail and the like, and a flanged head (5) engageable in abutment with the portion of the web surrounding said hole, said bush (1) having a through axial hole (10) in which a punch (15) is insertable for causing a radial expansion of said cylindrical stem (2) and a stable anchoring in said hole.

2. An electric contact, according to claim 1, characterized in that said punch (15) has, at one end, a threaded portion (16) engageable with the grip mandrel of a hydraulic jack adapted to pull said gauged punch through said axial hole (10) of said bush (1), said punch having an expansion cone (18) for causing said radial expansion of said bush.

3. An electric contact, according to the preceding claims, characterized in that said through axial hole (10) has, at the end on the side of said flanged head (5), a widened portion (11) for avoiding unwanted deformations of said head during the insertion of the punch (15) and for introducing lubricants and the like.

4. An electric contact, according to one or more of the preceding claims, characterized in that said punch (15) is adapted to generate an axial extrusion of the material of said bush (1) which is in excess with respect to the material required for the radial expansion of said cylindrical stem (2) in said hole (3).

5. An electric contact, according to one or more of the preceding claims, characterized in that said bush (1) coupled to said hole (3) by radial expansion of said cylindrical stem (2) has a flanged head (5) adapted to be electrically connected to a wire terminal (26) by bolting.

6. An electric contact, according to one or more of the preceding claims, characterized in that it comprises a through bolt (20) insertable in the gauged hole (10) obtained in said bush (1), a locking nut (21) engaging with said bolt and acting on a concave washer (23) having a concave portion (24) on the side directed towards the end of said bush to transfer the pressure produced by the bolt to the rail (4) without altering the electric contact between the bush and the rail.