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Патент USA US2406327

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Filed Dec. 2e, 1942 ‘
Patented Aug. 27, 1946
l Robert E. Friedrich, Pittsburgh 16, Pa., assígnor I
to Westinghouse Electric Corporation, East
Pittsburgh, Pa., a corporation of Pennsylvania
Application December 26, 1942,V Serial No. 470,159
6 Claims.
(c1. I20o-_166)
» -This invention ’relatesv to `'contact structures
and, more particularly, to the art of attaching
contacts of preciousmetals and refractory metals
'and their alloys to supportingrstructures of ybase
- »It 4i‘srdesirable to lmake the-contacts for use on
high-speed lcircuit interrupters of a light, elec
trically conducting metal selected 'from the >group
consisting of aluminum, magnesium vand their
having "an arcingV tip of arceresisting material
which'provides great mechanical strength, high
conductivity and which requires a - minimum
amount olf arc-‘resisting material.`
' These and other objects and advantages ofthe
invention will appear from the following detailed
description ofl one embodiment thereof whenvrea'd
in connection ’with the accompanying drawing,
in which:
alloys, such as zinc, silicon or copper, in order 10
Figure 1 is aside view, partly in se'ction,lof~a'n
to provide a ïm-inîmum Weight. An example of
arcing tip adapted to be attached> to the contact y
an alloy `which has‘been found satisfactory for
the 'main 'contact member consists of QLD/2% lalu
minum and ‘4.1/¿% cc'lpper.> Such metals »are un
to receive the arcing tip shown in Fig.~1"; h
suitable ror use :as >an arcing contact. Heretofore 15
Fig. 3 is an elevational vi'ew,rpartly in section,
it has been common ypractice to secure an arcing
showing the main contact body;
tip of arc-resisting material to the main contact
element in order to prevent excessive burning
of the contact. Such karc-resisting Y materials
Fig. 5 is an elevational View, partly ‘in section,
usually consist of copper-tungsten 0r silver 20 showing
the completed contact assembly.
tungsten mixtures formed to provide a refractory
According to the invention, a contact II (Fig.
contact tip 'which satisfactorily resists the dam
1) of an arc-resisting material, such, for ‘exam
aging' veffects of current arcs. Great difficulty
ple, as pressed and sintered mixtures of copper
has been encountered in attaching arc-resisting
tungsten or silver-tungsten or other known arc
contact tips to such contact members, since these 25 resisting materials, is formed substantially as
arc-resisting materials do not braze satisfactorily
illustrated, having a projection I3 inthe shape
to such metals. In trying to obtain goed me
chanical and electrical connections oiE such arc’
of a truncated cone integral therewith. Since it
has been found exceedingly difficult to obtain a
ing tips to contact structures of aluminum, mag
nesium and their alloys, various 'methods yof 30 satisfactory joint between such arc-resisting ma
terials and aluminum, magnesium and their
attaching the arcing tips to the contact structure
alloys, the arcing contact II is secured by brazing ì
have been resorted to. Such methods include
to the lianged head I5 lof a screw or bolt I1 com'
riveting, swaging», or soldering, etc. It has been
found, however, that repeated hammering 'of the
posed of a metal to which it mayr readily and
strongly be brazed, such, for instance, as brass.
contact tips, due to repeated operation of -the 35
Bra'zing the arcing tip l I to the bolt I1 is accom
plished by means of a high-strength brazing ma
and riveted vtips and to crack the soldered ljoints,
terial, such> as silver solder.
thus introducing high resistance Where the 'arcing'
The main body I9 (Fig. 3) of the contact strucù
occurs and to thereby further impair the effi
ture, which is of aluminum, magnesium and their
ciency of the contact.
40 alloys, is prepared to receive the arcing tip as
The principal object of the instant invention
sembly (Fig. 4) by drilling a hole 2l axially
is the provision of an improved contact structure
through the center of the member. 'I‘his opening
wherein an arc-resistant tip is secured to a con
is tapped from the contact end a distance suffi
tact member of aluminum, magnesium and their
cient to receive the threaded bolt I 1. The tapped
inter‘ru'pter, has a tendency to loosen-swaged tips
alloys in a manner to provide maximum mechan
ical strength and electrical conductivity.
Another object of the invention is the provision
of an improved contact assembly.
Another object of the invention is the provi
sion of an improved method of attaching an arc
resisting contact tip to a ' support or contact
member of aluminum, magnesium and their
45 end of main contact member I9 is then counter
bored as at 23, the counterbore having a diam
eter substantially equal to the diameter of the
annular projection formed by the projection I3
and the flanged head I5 of the bolt I'I. The
counterbore 23 provides the member I9 with a
conical shoulder 25 having the same angle with
reference to the axis of the member I9 as the
angle of the flanged head with reference to the
Another object of the invention is the provision
axis of the bolt I1.
of an improved contact structure of low mass 55
All of the surfaces of the assembly illustrated
in Fig. 4 andV of the main contact member, which~
is attached, said projection and said head form
will come into contact with each other, are next ~
ing an annular projection, a support member of
a light, electrically conducting metal selected
coated with a brazing material, such as tin, after
which the bolt I1 with the arcing contact II
attached thereto is screwed intol the tapped open
ing in the member I9. The head `I5 of the bolt
from the ' group consistingl of aluminum, mag- y
nesium and «their alloys, said support member
having an opening in which said screw and said
is seated firmly against the shoulder 25 by in-`
serting a screwdriver through the opening 2|
from thebase of the member into a slot 21 pro
vided for that purpose in the end of the bolt,
and turning the bolt to seat it securely in the
member I9.
ing a ñanged head to which said contact member
contact members are threacledlyv'Y mounted, said
opening forming a shoulder on k'saidsupport mem.
ber, said shoulder having Va portion extending
- Yinto the annular groove to embrace said annular f
projection and securelyhold all of the parts to
After the bolt and contact_assembly I’I-I'I
comprising a threaded
' 3'. Acòntact assemblyV
have been ñrmly seated in lthe member' I9, the»`-15 intermediate member, a contact of arc-resisting'
metal comprising the shoulder V29 'of the mainY
material secured to said intermediate' member by
contact member is forced into the groove defined l brazing, said »threaded member and said contactV
by the bottom of the «contact-tip II andthe pro'-¿
an annular'projection, a' support mem
jection I3 thereof by a swaging operation. The ` y ber
of a light, electrically conducting metal
complete assembly (Fig. 5,) 'is then passed through
20 selected from the group consisting of aluminum,
Y a suitable welding furnace and 'brought to Weld
magnesium andïtheir alloys; SaidV support mem- y
ber’having' a threaded opening in which saidî'in
termediatev member is threadedly mounted, a part
ing temperature .suñiciently high to melt ' the
brazingmaterial with which. the contactingsur
faces were coated. Thus' all of the contacting
surfaces of the members Il, l1 and I9 Yare firmly
' of said support member embracing said projection
25 to form a rigid mechanical connection between
' .
all of said members, the Yadjoining surfaces-_of
After vthis brazing operation, the annular
said members having a coating‘ofbrazing mate-'j
l' groove, formed by the swaging
rial to integrally secure said members togethenï
arcing contactand the shoulder 29 of the main
4.' A contact assembly comprising a contact
contact member I9, is ñlled with solder as at 3|
member of arc-resisting material anda threaded
(Fig. 5) to providebetter conductivity and a flush 30 support member brazed thereto, said members
brazed orwelded together.
smooth surface to the contact assembly.
It can be seen that a contact assembly made
forming an' annular projectio ‘, and a member
, having a threaded opening in which said support
in accordance with procedure set forth has great
member and said annular projection are mounted, .
mechanical strength and is capable of withstand
a portion of said support memberextendingover
ing repeated heavy blows, and also has a maxi
saidv projection and a part of said contact mem
mum of electrical conductivity due to the brazing
of all contacting surfaces.
Having described a preferred embodiment of Y
the invention in >accordance with the patent
statutes, it is to be understood that various 40
fcha'nges and modifications may be `made therein
without departing from the spirit of the inven
tion. It'is, therefore, desired'that the language
of vthe/appended claims be given as reasonably
broad interpretation as the prior art permits. l
l’. claim as my invention:
'Y _1. AV contact assembly- comprising a contact
member oi'arc-resisting material, a screw having
a flanged head to which said` contact member is
brazed, said iianged head together withV a part of
said contact member forming an annular pro
jection, asupport member having an opening in
5. A Contact assemblyY comprisingY a 4contact
member ofrefractory material having a periph- _
eral groove formedtherein, a headed screw- brazed
to said contact member, »a member having'a
threaded and counterboredy recess> for receiving
said screw and a part of said contact, a portion
of said member extending into the peripheral
groove in the contact member, and the adjoining
surfaces of'the contact member, the'screw vand
the member’being rintegrally. secured together by
a brazing material.
6. A contact »assembly comprising a contact
50 member of a light, electrically conducting >metal
selected from the group consisting of aluminum,
magnesium and'their alloys, said contactmem
ber having a threaded opening in'one end there
of, a metal screw mounted in said opening, and
a contact tip of arc-resisting material brazed on
support member embracing said projection to
the head of said screw, the end of said contact
hold vthe parts together.
member having a portion swaged over against a
2. A contact assembly comprising >a contact
portion of said contact tip. ,
' '
member of arc-resistingv material having a pro
jection forming an annular groove, a screw hav
which said screw and a part of said contact mem
bers are threadedlyl mounted, a portion of said
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