WO2008037714A1

WO2008037714A1 - Cable with lug for thermite welding, the lug having a stepped portion

Info

Publication number: WO2008037714A1
Application number: PCT/EP2007/060163
Authority: WO
Inventors: Daisuke Funamizu; Hideki Nishijima
Original assignee: The Furukawa Electric Co., Ltd.
Priority date: 2006-09-25
Filing date: 2007-09-25
Publication date: 2008-04-03
Also published as: JP2008073762A; JP2010504217A

Abstract

The present invention improves the strength of a welding lug (1) and increases the welding area in thermite welding. The cable (5) with lug (5) for thermite welding of the present invention is thermite welded to a base metal via welded metal from solidification of a welding material that has flown in. The cable and lug (1) comprises a first portion (3) having a shape such that the surface of the recess portion is in direct contact and flush with the surface of the second opening portion, which is at least partially in a lengthwise direction of the recess portion; a second portion (4) extending from one end portion of the first portion (3) to the inside of the cavity portion, which is separated by a predetermined distance from the surface of the first opening portion.

Description

CABLE WITH LUG FOR THERMITE WELDING, THE LUG HAVING A STEPPED PORTION

TECHNICAL FIELD

The present invention relates to a cable with lug for thermite welding, more specifically, a cable with lug for thermite welding employed with a conventional welding tool, which when conventionally compared, is capable of increasing the welded area of a base metal and cable with lug for thermite welding.

BACKGROUND ART

Thermite welding is welding in which a mixed powder of aluminum and copper oxide (or iron oxide) is ignited and combusted near the surface of a base metal, and a portion of the base metal and copper (or iron) is melted by the heat of a chemical reaction thereof. The applications of thermite welding are mainly employed in railway fields in cases where two base metal rails are electrically connected to each other using a copper cable or the like, referred to as a bonding cable, and in cases where pipelines buried in the ground are connected. FIG. 5 illustrates an aspect of thermite welding in which rails for a railway are thermite welded.

A special tool must be employed in order to thermite weld, and hereinafter, the special tool be referred to as a crucible, and the part which welds the base metal with the welding lug connected to the copper cable or the like at the portion constituting the crucible will be referred to as the welding jig. Hereinafter, the construction of a conventional crucible will be explained with reference to Figure 6 (a) . Crucible 61 contains a combustion chamber 65 for containing a thermite material 62 and an ignition material 63 therewithin, igniting the ignition material 63 and combusting the abovementioned materials, a passageway 67 for channeling the molten thermite material 62 after combustion, an insertion portion 69 for inserting a welding lug connected to a cable, and a recess portion 68 into which the molten thermite material 62 from passageway 67 flows, in order to weld the welding lug to the base metal. The recess portion 68 and insertion portion 69 have openings in surface 70.

Before combustion, the bottom of the combustion chamber is covered with a steel disc 64, with passageway 67 extending downward therefrom.

As preparation before performing thermite welding, as shown in Fig. 6 (b) , the thermite material 62 and the iginition material 63 with which it is covered are packed. Next, at least the end of the lug is placed into recess portion 68, and the cable connected to welding lug 71 is placed into insertion portion 69, by having a shape which is complimentary to the shape of insertion portion 69. Also, surface 70 and the surface of the welding lug 71 abut with the surface of the base metal (not shown) to seal recess portion 68. Moreover, surface 70 is flush with the surface of the welding lug 71.

Next, in order to perform thermite welding, the combustion reaction indicated below is started in the thermite material 62 (shown in the example of copper thermite welding) by igniting the ignition material 63, and the metallic elements constituting the thermite material 62 are melted, via the exothermic heat of the abovementioned reaction .

2Al+3CuO → 3Cu+Al₂O₃+ΔQ (exothermic heat)

At that time, the steel disc 64 is also simultaneously melted, and the molten metal flows out downward through the passageway 67 and flows into the recess portion 68 from the passageway 67. Consequently, a portion of the welding lug and base metal are also melted within the recess portion 68

(the lug end of the cable also being included) , and after cooling, the welded portion (refer to 72 of FIG. 6 (c) ) is formed on the surface of the base metal with a portion of the welding lug (containing the cable inside) included inside, with the base metal 73 being fused to the welding lug 71 via welded portion 72. The surface of the base metal, welding lug and welded portion after thermite welding, as seen from a side view is shown in Figure 6 (c) . At the time of actual thermite welding, operations such as base metal polishing, preheating, removal of the post thermite welding crucible, slag removal, shaping, etc., are necessary. However, since these operations are common knowledge to those who are skilled in the art, a detailed explanation will be omitted.

Japanese Patent Publication No. 2005-7461 discloses such a welding method. DISCLOSURE OF THE INVENTION

PROBLEM(S) TO BE SOLVED

The portion of the molten metal that is welded in the abovementioned conventional welding jig employed in thermite welding, is indicated in FIG. 6 (c) , in which with respect to the welding lug, region Z, as indicated by the dotted line, is roughly equivalent surface portion of the welding lug that is placed inside recess portion 68, and with respect to the surface of base metal 73, the inner opening portion of recess portion 68 in the surface 70 of crucible 61, excluding the weld lug, is region V. The welded area of the base metal and welding lug is determined by the position at which welding lug 71 is placed inside of recess 68 before thermite welding, in order to maintain the balance between region V and region Z. Consequently, if the region of welding lug 71 placed inside recess 68 increases, then the welding area on the surface of the base metal 73 decreases, and if the region of welding lug placed inside recess portion 68 decreases, then welding area on the welding lug decreases. Therefore, regardless of the case, since region W which is adjacent to the surface of the base metal and welding lug is not welded, the weld is unstable from the point of welding strength.

Furthermore, welding lugs of conventional cables with welding lugs, normally, are generally fabricated out of copper and connected to the cable inserted inside the welding lugs via a crimping process. Therefore, for example, in cases where thermite welding is performed on rails for a railway using a cable with a copper lug in order to electrically connect two separated rails of a railway to each other, even though copper is high in malleability and ductility, since copper is not significantly high in strength, it is possible that a lug affected by an external force will break.

MEANS FOR SOLVING THE PROBLEM(S)

As a result of thorough experimentation, in order to solve the above mentioned problem(s), the applicants have invented a cable with lug for thermite welding in which, when a welding lug connected to the cable is placed at a predetermined position of a welding jig at the time of thermite welding, at least a portion of the insertion portion in a lengthwise direction becomes flush with surface 70 of the welding jig, with the cable with lug for thermite welding being integrally formed with a first portion forming a sealed portion sealing a through passage to recess portion 68, and a second portion extending inside recess portion 68 from the end of the first portion, while being separated from surface 70 by a predetermined distance. Therefore, when performing thermite welding, the inner space separating the insertion portion 69 and the surface of the base metal, or the space (W region) between the second portion and the surface of the base metal can also be welded. Furthermore, in order to solve the abovementioned problem (s) in cases where a copper lug is employed, a cable with welding lug is provided, in which the welding lug is made of iron, and integrally connected by crimping and processing, so that the cable inserted inside is in direct contact with the entire welding lug, and thereby, able to withstand external force. (1) In order to achieve the abovementioned objective, the cable with lug for thermite welding of the present invention is thermite welded to a base metal via welded metal from solidification of a welding material that has flown in, using a welding jig provided with; a cavity having a first opening on the surface abutted with the surface of the base metal into which the welding material flows; and a recess portion communicating with the cavity portion and having second opening portion on the surface thereof abutted with the surface of the base metal, the cable having a conducting wire inserted inside, and comprising: a first portion having a shape such that the surface of the recess portion is in direct contact and flush with the surface of the second opening portion, which is at least partially in a lengthwise direction of the recess portion; a second portion extending from one end portion of the first portion to the inside of the cavity portion, which is separated by a predetermined distance from the surface of the first opening portion .

(2) Moreover, the cable with lug for thermite welding of the present invention may form a stepped portion by having the surface of the first portion flush with the surface of the second opening portion, and the surface of the second portion opposing the surface of the first opening portion .

(3) In addition, the cable with lug for thermite welding of the present invention may be filled with the welded metal in the space between the surface of the base metal and the surface of the second portion, by thermite welding. (4) Furthermore, the welding lug of the cable of the present invention may be made of iron.

SUMMARY OF THE INVENTION

In a first embodiment of the present invention, since a cable with an iron lug for thermite welding is constructed to have, a first portion having a shape that is flush with the surface of the opening of the second opening portion and is in direct contact with the surface of the recess at least partially in the lengthwise direction of the recess of the abovementioned welding jig, and a second portion extending from one end of the first portion to the inside of the cavity, separated by a predetermined distance from the surface of the opening of the first opening portion, when thermite welding is performed, a welded portion, into which the thermite welding material in the space between the second portion and the surface of the base metal having mutually opposing predetermined spacing flows is formed, and as a result, the weld area of the cable with the iron lug for thermite welding and the base metal can be increased.

In a second embodiment of the present invention, a first portion and a second portion form a stepped region. This may be a process whereby, a cable is inserted inside a lug inner portion, crimping begins from a predetermined position of the lug together with the inner portion of the cable, and portions of increased and decreased thickness are formed, so that the cable with lug for thermite welding can be easily manufactured.

In a third embodiment of the present invention, since at least the space between the surface of the base metal and the surface of the second portion are filled by the weleded metal, the welded area is increased as compared with that of conventional cables with welding lugs, and therefore, welding strength can be improved. In a fourth embodiment of the present invention, since the welding lug is made of iron, the strength of the welding lug is improved, and therefore, the welding lug has the advantage of making breakage, etc. of the weld lug from external forces difficult, even if a portion has undergone plastic deformation by crimping and such.

BRIEF DESCRIPTION OF THE DRAWINGS

[FIG. 1] A perspective view of a cable with welding lug of the present invention;

[FIG. 2] A diagram of the cable with welding lug of the present invention placed in an insertion portion of a conventional crucible;

[FIG. 3] A diagram of a side surface, showing a surface of the weld lug and a surface of the metal base which are connected via a welded portion after thermite welding of the present invention;

[FIG. 4] Another embodiment of the cable with the welding lug of the present invention;

[FIG. 5] A diagram of thermite welding being performed on a rail for a railway; and [FIG. 6] (a) is a crucible of conventional technology, (b) is a diagram showing an alignment of the cable with a welding lug of conventional technology, and (c) is a side surface after thermite welding by conventional technology.

PREFERRED MODE FOR CARRYING OUT THE INVENTION

Example (s) of preferred embodiment (s) of the present invention shall be explained below with reference to the drawings. Moreover, in each drawing, the same constituents shall be designated by the same reference numerals, and when appropriate, explanations thereof shall be omitted.

Example (s)

Example 1

FIG. 1 illustrates a slant view of a cable with a welding lug 1 of the present invention. The abovementioned cable with welding lug 1 consisting of a copper or the like cable 5 inserted into a lug having a through hole, an outer surface that is plastically deformed by crimping and such of the lug and cable, consisting of a stepped portion 6 connecting the two substantially rectangular shaped surfaces

3 and 4, and an arch-shaped surface 2. The cable 5 is in close contact with the inner surface of the lug.

FIG. 2 illustrates a diagram of the cable with weld lug 1 of the present invention placed in cable insertion portion 69, in order to perform thermite welding employing the conventional crucible 61 illustrated by Figure 6. The welding jig constituting the crucible 61 is provided with a cavity portion 68 having an opening portion in surface 70 abutting the surface of the base metal (not shown), into which the welding material flows, and an insertion portion 69 having an opening portion in the surface 70 abutting the surface of the base metal (not shown) and communicating with the cavity portion 68.

The welding lug of the cable with the weld lug of the present invention is such that partially in the lengthwise direction of the inside of insertion portion 69, the surface 2 of the arch is in direct contact with the inner surface of the insertion portion 69, and the substantially rectangular surface 3 becomes flush with surface 70. Furthermore, the welding lug of the cable with welding lug in cavity portion 68 and the remaining portion of the insertion portion 69, is in direct contact with the inner surface of insertion portion 69, the portion that includes surface 4 extending to the inside of the cavity portion 68, the surface 4 and surface 70 being separated by a predetermined distance by a stepped portion 6 therebetween.

Consequently, by having the surface 70 abut the surface of the base metal which is not illustrated in figure 2, thermite welding is performed with the cavity portion 68 and the insertion portion 69 sealed. Moreover, since the molten metal that has flown into the cavity is sealed by an abutment of the surface of the base metal and the surface 70 and an abutment of the surface of the base metal and the surface 3, the molten metal does not leak outside of the welding jig. FIG. 3 shows a side surface diagram in which the condition of the surface of the welding lug and the surface of the base metal welded via a welded portion in thermite welding is indicated. In FIG. 3, molten metal flows into space 30 between the surface 4 of the welding lug 4- and the surface of base metal 33 via the stepped portion 6 of the welding lug at the time of thermite welding, and the welded portion is formed. Consequently, it was found that when the welded region V of the surface of base metal 33, and the welded region Z' on the outer surface of the welding lug indicated by the dotted line are compared with each of the welded regions V and Z of conventional technology in FIG. 6 (c) , the welded area was increased.

Next, another embodiment of the cable with weld lug of the present invention is illustrated in Figure 4. FIG. 4 (a) shows a perspective view of the cable with welding lug consisting of the first portion having the arch-shaped surface 2 and the substantially rectangular shaped surface 3, and the second portion having surface 4, crimped from the end surface of the first portion and formed into a substantially cube-like shape. When the abovementioned cable with welding lug is placed in a welding jig, the arch-shaped surface 2 of the first portion is placed in direct contact with the inner surface of the insertion portion 69, and the second portion is placed inside the cavity. In an embodiment of FIG. 4 (a) , only the arch-shaped surface 2 of the first portion is formed to mach and be able to align with the inner surface of the insertion portion. Therefore, in cases where the second portion including the surface 4 of the abovementioned cable with welding lug is placed in insertion portion 69 during the preparatory process of thermite welding, it is clear that misalignment from backlash inside insertion portion 69 occurs. Therefore, when thermite welding is performed with the surface of the base metal abutting surface 70 and surface 3, the second portion 2 is covered with molten metal, the molten metal also flows into the spaces between the surface 4 of the second portion and the surface of the base metal to form the welded portion, and as a result, the welded area is increased, and the weld strength is improved.

FIG. 4 (b) illustrates a perspective view of the cable with welding lug, in which the cable is inserted into the welding lug, processed by having the weld lug and cable plastically deformed into a substantially cube-like shape by crimping or the like, and further forming the stepped portion 6 in a surface thereof, which thereby connects surface 3 and surface 4. The abovementioned cable with welding lug has the advantage of being easily manufactured, since the welding lug and cable are processed into a cube- like shape, and thereafter only a process of forming a step in a surface thereof is employed. However, the inner surface of the insertion portion of the welding jig must be formed to match an outer surface other than that of surface 3 and surface 4. Therefore, after alignment into the insertion portion of the welding jig, when thermite welding is performed with the surface of the base metal abutting surface 70 and surface 3, the molten metal also flows into the spaces between the surface 4 and the surface of the base metal to form the welded portion, and as a result, the welded area is increased, and the weld strength is improved. Example 2

In another embodiment of the present invention, the welded lug that is processed with crimping along with the cable is made of iron. In order to connect the iron lug and cable, the cable is inserted into the iron lug having a through hole in the inner portion thereof, and simultaneously crimped to form the stepped portion in the surface opposing the surface of the metal base and bring the iron lug and cable in direct contact at the inner portion. In cases where the welding lug is made of iron, since the strength of the welding lug is increased, there is no damage to the lug, even when an external force is applied, thus ensuring a superior weld in both iron and copper thermite weldings.

When compared to conventional employed welding lugs, the cable with welding lug of the present invention can increase the weld area, and prevent the occurrence of welding lug damage after thermite welding.

Claims

1. A cable with lug for thermite welding that is thermite welded to a base metal via welded metal from solidification of a welding material that has flown in, using a welding jig provided with; a cavity having a first opening on the surface abutted with the surface of the base metal into which the welding material flows, and a recess portion communicating with the cavity portion and having second opening portion on the surface thereof abutted with the surface of the base metal, the cable having a conducting wire inserted inside, and comprising : a first portion having a shape such that the surface of the recess portion is in direct contact and flush with the surface of the second opening portion, which is at least partially in a lengthwise direction of the recess portion; a second portion extending from one end portion of the first portion to the inside of the cavity portion, which is separated by a predetermined distance from the surface of the first opening portion.

2. The cable with lug for thermite welding according to claim 1, wherein the surface of the first portion which is flush with the surface of the second opening portion, and the surface of the second portion opposing the surface of the first opening portion form a stepped portion.

3. The cable with lug for thermite welding according to claims 1 or 2, wherein at least the space between the surface of the base metal and the surface of the second portion is filled in by the welded metal.

4. The cable with lug for thermite welding according to any of claims 1 to 3, wherein the welding lug is made of iron.