US2416883A

US2416883A - Rail bond or the like

Info

Publication number: US2416883A
Application number: US529295A
Authority: US
Inventors: Selquist Rolf
Original assignee: Copperweld Steel Co
Current assignee: Copperweld Steel Co
Priority date: 1944-04-03
Filing date: 1944-04-03
Publication date: 1947-03-04
Anticipated expiration: 1964-03-04

Description

March 4, 1947. R SEL QUIST 2,416,883

RAIL BOND 0R LIKE Filed April 5, 1944 2 Sheets-Sheet ,1

INVENTOR March 4, 1947. R. SELQUIST 2,416,833

RAIL BOND OR THE LIKE Filed April 3, 1944 2 Sheets-Sheet 2 J5 ll 'iasl'fil'o No. of (yaks-Thousands INVENTORI Po/fSe/gwlsf Patented Mar. 4, 1947 RAIL BOND OR THE LIKE Rolf Sc'lquist, McKeesport, Pa., assignor to Cope perweldiSteel Company, Glassport, Pa., av cor poration of Pennsylvania Application April 3, 1944, Serial No. 529,295

2 Claims.

This invention relates to electrical connectors, such as rail bonds, and a method for their manufacture.

One type of rail bond or electrical connector which has been extensively used comprises a suitable length of conductor, usually a stranded cable of appropriate size, welded to one or more plugs having tapered shanks and adapted to be driven into holes drilled in the webs of railroad rails. Annealedwire has been used heretofore for the conductor because of the necessity for bending the conductor which is shipped straight, to the desired curvature adjacent the ends when installing it in the field. The necessity for manually shaping the conductor has prevented the use of hard-drawn wire, even though it is stronger than annealed wire, in making a bond of the conventional welded type. Bon of h s yp have in certain cases exhibited fatigue failure of the conductor adjacent the head of the plug. It will be appreciated that, under the conditions of service existing on railroads carrying heavy traflic, rail bonds are repeatedly subjected to severe vibration and impact so that the resistance of a bond to failure by fatigue is one of its most important qualities. 7

The object of my invention is 'to provide a rail bond or the like havinga conductor of harddrawn wire throughout and therefore characterized by a greater fatigue strength than the bonds including conductors of annealed wire welded to drive plugs. In a preferred embodiment, my improved bond comprises a suitable length of conductor, preferably stranded, composed of hard-drawn wire, inserted through 'a transverse hole in the head of a drive plug, the conductor being secured to the plug substantially exclusively by the frictional grip of the latter on the former.

A complete understanding of my novel bond and method of manufacture may be obtained from the following detailed description which refers to the accompanying drawings illustratin a preferred embodiment and practice. In the drawings,

Figure 1 is an elevation of a drive plug adapted to receive a conductor to form a bond according to my invention;

Figure 2 is a similar view taken at right angles to Figure 1;

Figure 3 is a partial section through a deforming apparatus adapted to operate on a plug having a conductor inserted therethrough;

Figure 4 is a partial elevation of a bond after completion of the head-deforming operation;

' the countersink l5.

Figure 5 is an elevation to enlarged scaleof the bond taken at r ght angles to Figure 4;

Figure 6 is a partial section also to enlarged scale taken along the plane of lineof Figure 4; and

Figure 7 is a set of curves showing graphically the performance of my bond under fatigue test, as compared with bonds having conductors welded to the drive plug. I

The'iinproved bond of my invention may best be understood from a description of the method by which it is manufactured. In the preferred method, I provide a drive plug Ill having a head H and a tapered shank T2. The top of the head may conveniently have the form of a spherical segment as indicated at l3. A transverse hole H is drilled through the head on a diameter thereof and i countersunk as at 15.

To attach a conductor to the plugill, I insert a length of suitable conductor it of hard-drawn wire, free from the softening resulting from annealing, preferably a stranded cable, through the hole I4 until the end of the cable is substantially flush with the end of the hole opposite As shown in Figure 4, the size of the hole [4 is such as to provide slight clearance for theconductor to facilitate insertion of the latter. When the conductor has been in-' serted in the hole through the head of the plug, 1' subject the head to a deforming operation Whereby the head is caused to obtain a tight frictional grip on the conductor. This peration may conveniently be effected by apparatus such as that indicated diagrammatically in Figure 3, including a die plate I! resting on a base plate l8 which may be the platen of a press having a reciprocable head 19. The die plate ll has a tapered bore 28 therein adapted to accommodate the shank l2 of the plug in axial alignment with the head l9.

When the die head l9 of the press is caused to descend with sufficient force, the head It is deformed by compression or squeezing so that it obtains a tight frictional grip on the conductor. The hole I4 is somewhat contracted and the conductor itself, if stranded, is slightly compacted. If the die head I!) is plane on the end, the spherically shaped top l3 of the head I l is flattened asindicated at 2| in Figure 4 which showsone end of a completed bond, the other end being identical. If it is desired that the heads of the plugs retain a rounded top after deformation, the die head I9 may be made concave at its end.

Figures 5 and 6 further show the finished bond. The end of the conductor is slightly flattened as a result of the crushing down of the plug head under the force of the press, as shown in Figure 5. The interior of the hole I is slightly indented by the strands of the conductor, as shown in Figure 6,. if the head of the plug is sufificiently deformed. This is desirable since it improves the frictional grip of the head on the conductor, lessening the chance that the conductor will be pulled out of the hole in service. The countersink I5 is an important feature in that it elimithe plug. A further advantage is that my im- 1 actly the same manner as Til proved bond may be applied to the rail in exused.

It will .be apparent that, while the invention has been described with particular reference to bonds,

it is also useful in connectors which have a drive plug at one end only of the conductor.

nates the sharp edge of the hole which might otherwise nick or notch the strands of the conductor under severe vibration in service, which Although I have illustrated anddescribed but a. preferred embodiment and practice of my invention,

it will be understood that changes in the design of the parts or in the manufacturing prowouldreduce the fatigue resistance of the bond,v

7 It also prevents the applicationof compressive stress to the conductor where it leaves the head,

which would otherwise result in a region oflocalized stress concentration further tending to reduce the fatigue resistance.

Figure 7 shows graphically the comparison between my-improved'bond and the welded bond under fatigue test. In this test, samples were subjected to repeated bending of the conductor in opposite directions through small angles while the plug was held firmly fixed. Curve A is drawn through the experimental points designated by dots, obtained in tests of welded bonds. Curve B is. drawn through experimental points indicated by circles, obtained from tests on the bond of my invention. It will be readily apparent that my bond exhibits considerably higher endurance spirit ofthe invention or pended claims.

cedure may be made without departing from the the scope of the ap- .I claim:

1. A rail bond comprising a pair of drive plugs and a length of conductor, said conductor being composed of hard-drawn wire and having its ends 1 extending into said plugs, respectively, and secured therein by affrictional grip, wherebythe conductor is left in its original hard-drawn state and remains free from thesoftening resulting from annealing, at least in the portions thereof adjacent the plugs, and is therefore more resistant to fatigue failure under the repeatedvibration to which it is subjected-in service'th'an a bond having a conductor which has been anunder fatigue test than the welded bond. That is to say, for the ame angle of bend, my bond withstood a great many more repeated cycles of bendin than the welded bond or, for the same 1 numberof bends, my bond could bebent through a considerably greater angle than the welded bond. This increased'endurance results from the use of hard-drawn wire forthe conductor and a method of attaching it to the plugs which does not involve heating the'wireto a temperature above the critical point, leaving the wire in its original hard-drawn state throughout.

My invention is also characterized by further 1 j advantages. In the first place, the cost is lower than that of the welded bond since the deformation of the headof the drive plug is a less expensive operation than the welding of the conductor to the head. My bond has a total resistance substantially the same as that of the welded bond. My bond is also characterized by ample resistance to'pulling out of the oonductorfrom healed at the points of connection to the plugs. 2. A rail bond comprising a length of conductor with a drive plug at each end thereof, the ends of the conductor extending into holes in the plugs, respectively, and secured therein by a frictional grip, said holes being countersunk at. the

ends into which the conductor extends, thereby preventing localized stress concentrations at the point where the conductor enters the plugs,

' ROLF SELQUIST:

' REFERENCES CITED '7 e The following references areof record in the file of thispatent: Y

the bonds previously PATENTS] 1