US3188722A - Method of and apparatus for making brush contact assemblies - Google Patents

Description

June 15, 1965 J. R. LORCH 3,138,722

METHOD OF AND APPARATUS FOR MAKING BRUSH CONTACT ASSEMBLIES Filed June 19, 1961 2 Sheets-Sheet 1 INVENTOR James R. Lorch @EIfiA BY ATTORNEY June 15, 1965 LORCH 3,188,722

METHOD OF AND APPARATUS FOR MAKING BRUSH CONTACT ASSEMBLIES Filed June 19, 1961 2 Sheets-Sheet 2 INVENTOR James R. Lorch BY W w ATTORNEYS United States Patent 3,188,722 METHOD OF AND APPARATUS FOR MAKING BRUSH CONTACT ASSEMBLIES James R. Lorch, Pinole, Califi, assignor to SCM Corporation, a corporation of New York Filed June 19, 1961, Ser. No. 118,177 5 Claims. (Cl. Z9--155.5)

The present invention relates to methods of manufacturing wire brush contact assemblies and apparatus used in the method, and more specifically to a method wherein each brush contact is composed of multiple wires.

The multiple brush contact assembly of the present invention is particularly well adapted for use in the program device as described in my copending application Serial No. 100,169 filed April 3, 1961, and is adapted to be mounted on a fixed base of the typewriter with the contacts facing upwardly. The flexible contacts thus positioned may sense perforations in a perforated tape or record member having a plurality of channels and attached to the underside of the typewriter carriage. The wire brushes are electrically isolated from one another and are adapted for use as means to program a data processing system in accordance with the position of the typewriter carriage.

The brush contact assembly as described in connection with the novel method of the present invention is similar in many respects to the brush contact assembly disclosed and claimed in US. Patent No. 3,072,238 issued January 8, 196-3, to Gim P. Chan and assigned to the assignee of the present invention. A particular shape of the contact brushes as disclosed in the Chan application provides a smooth slide over the unperfor-ated surfaces of the tape or record member with minimum wear and a smooth camming action into engagement with and out ofa perforation in a card or tape regardless of the direction of relative movement bet-ween the brush assembly and the perforated record member. To achieve the foregoing advantageous wear properties, each brush has been formed from a plurality of individual wires having diameters in the order of 5 to 20 mils which are secured together at their ends and formed in such way to prevent crossing of the wires, splaying or turning of the wires in grooves in which they are mounted.

In the method previously used for forming the contact brush assembly, the contact wires were soldered to a notched piece of copper-clad phenolic. This resulted in all or nearly all of the wires being shorted together to form an electrically common brush. The notched pieces of copper-clad phenolic were actual parts of the final product and remained permanently attached to the contact wires of the brush assembly throughout all subsequent assembly operations. Problems were thus presented in the prior method which inherently prevented the construction of a contact brush assembly where the brushes were electrically isolated, but yet retained all t of the advantages of the multiple wire contact brush assembly as disclosed in the above-identified Chan application.

The principal object of the present invention is to provide a novel method of forming a brush contact assembly of the type wherein each brush may be electrically isolated from the other brushes and yet composed of a plurality of individual wires.

Another object of this invention is to provide in a method of making a contact brush assembly, an improved method of cutting, locating and positioning the individual wires for each brush on throw-away support post mem bers, and then after formation of the V contacts at the center of the brushes, of securing the ends of the brushes to a phenolic insulating material which serves as the "ice base member. After the brushes are secured to the base member, the throw-away support post members may be cut off thereby leaving each multiple wire brush in its desired position on the brush contact assembly with each of the brushes electrically isolated from the other brushes.

A further object resides in the step of soldering the wire as cut from the coil to the throw-away support post members and causing the solder to run along the wires toward the center of the brush a distance sufiicient so that when the throw-away post members are cut off, the wires forming each individual brush remain soldered together to be both electrically and mechanically secured to each other at the opposite ends of the brush assembly.

A still further object of the invention is to provide an improved jig assembly wherein the jig assembly has slotted guide members to serve as means for positioning and orienting the wires as they are cut from a coil and slots for receiving the throw-away post members on which the contact wires are initially soldered during the assembly operation.

These and other objects of the invention will become more fully apparent from the claims, and from the description as it proceeds in connection with the drawings wherein:

FIGURE 1 is a plan view of the contact brush as-. sembly of the present invention shown in its condition just prior to the time throw-away post members 114 are removed;

FIGURE 2 is a side elevation view of the contact brush assembly of FIGURE 1;

FIGURE 3 is a pictorial view of the solder jig assembly showing the three wires which make up one brush in position for soldering;

FIGURE 3A is a partial section of the solder jig assembly of FIGURE 3 showing the position of the wires when they are soldered as seen along lines 3A3A;

FIGURE 4 is a side elevation view of the jig assembly of FIGURE 3 FIGURE 5 is an elevation view of a two piece die assembly used for forming the V portions on the brush contacts.

Referring now to the drawings and more particularly to FIGURES l and 2, the contact brush assembly 20 made in accordance with the present invention may have a channel shaped base member 22 formed of a suitable electrical insulating material such as phenolic resin having two upwardly extending edge portions 28. The upper surfaces 34- of edge portions 28 lie in a common plane and may be provided .with shallow parallel grooves into which the ends 23 of the contact brushes 40 are secured. The contact brushes 40 are thus insulated from each other on both ends of the contact brush assembly 20.

Suitable apertures 31 and 32. may be provided in base 22 for mounting brush assembly 20 on a piece of equipment such as a typewriter. A cover member 29 of a suitable plastic insulating material is secured as by an adhesive on opposite end surfaces 34 of base member 22 and is provided with elongated slots 30 through which the central V shaped portions 44 of brushes 40 extend. The side edges of slots 30 prevent the central V portion 44 from deflecting laterally to thus assure that each brush 4% retains its desired alignment.

Each of the individual brushes 40 illustrated in FIG- URES 1 and 2 is composed of three beryllium copper wires, with each wire having a diameter on the order of 5 to 20 mils. The central V shaped portion 44 has a tip 46 which is rounded and smoothed on both sides to ret 3 p duce wear on a perforated record with which the present invention is adapted for use.

In an exemplary practical application, the contact brush assembly may be mounted on a stationary part of a typewriter in the manner more fully disclosed in the Chan Patent No. 3,072,238 identified above, in vertically spaced relation beneath a perforated program tape of anv program tape relative to the perforations with minimum Wear upon the. tape regard-" less of direction of movement of the carriage.

Contact wires, three of which aroused to form each brush 40, are cut from a long lengthof wire conventionally shipped from the manufacturer intthe form of a coil.

The first step in the method' of forming. contact Wire groups or brushes 40in accordancewith the present in vention is accomplished on the apparatus best illustrated in FIGURES 3 and 4'; The apparatus 100. comprises a solder jig assembly composed of a substantiallyrectangular base member 102 having anupper surface 104 ,cu'rved throughout its longitudinal extent with a radius corresponding approximately'to'the radius of curvature of the wire coil, not shown. 7 Adjacent thelongitudinally. opposed ends of the base member 102 is a pair of parallel, laterally extending slots 106 which are spaced a preselected distance apart greater than the length of the wires usedrin the finished contact assembly block. 20. Spaced inwardly from slots 106jis another pair of parallel slots 108. The. distance between slots 108 maybe somewhat less than thelength of the wires in the finished 4 side-by side parallel relation with their respective opposite ends, 23 'dr'ooped downwardly; The three contact wires 5 for each brush 40 are then positioned in theirside-by-side relation on the curved surface 104 of solder jig assembly through a pair of axiallyaligned slots 112 in guide members 110. The three contact wires in a single guide slot 112 on the solder jig assembly 100'are then secured'as by soldering at one end to the adjacent post member 114.

During the solderingioperation, solder is caused to run up the contact wires to slots 112 in guide members 110.

'As guide members 110 are of aluminum, the solder does not adhere to them. This secures the contact wires of each brush together along a length of the brush'to prevent splay, crossover or turning of the individual wires vrelative to one anotheri I With the unsoldered ends of the contact wires freely drooped across surface 104 and support post'114 solder is then applied to them and-their support post 114. Again the solder'is run up the contact wires to the location of guide member 112.. This foregoing step of soldering is v performed without the application of a tension force on the wires as used in the method disclosed in the Gim Chan patent identified above, and at a time when the wires are eachdisposed freelytonthe solder jig assembly 100 ,in'side by side relation with their natural curvature onforming'to that of theupper curved surface of the base member 102 throughout their lengths.

After all of contact brushes'40 have been secured at both ends to and betweenthe support post members114, screws 120 are'loosened and-thegcontactbrush sub-assembly thus formed is removed from the solder jig assembly. ,The next step in the; manufacture of the contact brushes isthe formationrofa'V in the "central portion of the contact. brushes which is accomplished on the following contact assembly block20. Guide'members .110 may be 1 secured in the receivingslots 108 by an adhesive or if desired by fasteners to permitdifferent brush arrangements and spacings to be formed,

, .Ea'ch guide member 1101has slots 112 at pre-selected 7 positions for locating the Wires in. groups andat positions which determine the grouping of brushes 40 on brush assembly 20. of FIGURE 1. Slots 112 in guide members 110 are in axial alignment, and each guide slot 112 has a widthsufficient to receive. the three separate wires which form each brush 40. vAlso, the bottom surfaee'of each guide slot 112 is preferably flush with the upper curved surface 104 of the base member 102. It will be seen,

therefore, that three contact wires are received in the.

guide slots 112 exactly as they fit in side-by-sideabutting relation and conform to the upper curved surface 104 of the base member as the natural curvature of the contact wires corresponds to the curvature of upper surface 104 of the base member 102. t

Post members 114 that are loosely received in are; preferably made of metal, or at least have an upper metallic surface. Post members 114 are secured in position' during the initial steps of'forming the brush assembly in slots 106 as by screws 120 which are threaded through bores 118. The upper surface of each member 114 is slots 106 substantially flush with curved surface 104 of the base member 102 so that the contact wires when placed on upper curved surface 104 of base member102 will be in a position to be easily secured' to'post members 114'by an electrically conductive bonding agent such as a solder or electrically conductive paste or cement.

The assembly 'procedureis as follows: after screws 120 are backed off, post members'114' are inserted into the slots 106 and screws 120 tightened to hold support posts 7 wire bending die assembly'as shownin'FIGURE 5' in a manner as disclosed and claimed in the Chan patent. The die assembly may conveniently comprise a base member 200 having a length comparable to the length of support post members 114." .Four pins 202 extend upwardly from each of the four corner positions-to serve as guides for upper die member 204. On opposite side walls clamp elements 206 and screws 208 which may be tightened maybe provided southat support posts-114 are lightly clamped when'contact'wires of brushes'40 are at corner edges 210 and 212 "of base member 200. V

r The upper surface of base member 200 has a pair of surfaces '21'4 and 216 which slope inwardly :and downwardly. At the, center, aninverted V section is pro- -nating in an apex having a small radius of curvature as illustrated. The lower surface of the upper die memher 204 has a complementary configuration so that when it istpressed downwardly, all of the wire groups are simultaneously forced across the upper surface. Suflicient force is used to cause permanent deformation of the contact brush forming wire groups 40. Care must be taken at all steps to preventthe-wires in each individual group from crossing; After upper die member 204 is raised, the wires have a permanent configuration similar to that shown in FIGURE 2. a j

Each' wire in each contact wire group 40 is made the same length,,and by using only lengths of new'w re that are free of sharp bends, each wire issubstantially equally uniformly internally stressed and has the same resilience. The brushesthus formed therefore have parallel configurations. By forming the Y contact portions after securing the ends of the wires to support post members 1-14, the upper curved portion 46 (FIGURE 2) of each wire group 40'forming each brush is located along a straight 'line centrally located :between support posts 114 and at a uniform distance from a reference plane such asthe surface of a. program tape backing plate.

7 Afteri'the central V has been impressed in the contact brushes by the die assembly, the contact 'brush sublassembly' isthen placed on surfaces 34 of upwardly extending edge portions 28 of contact carrier block 22 shown in FIGURES 1 and 2. Surface 34 is provided with shallow grooves having a depth approximately equal to the diameter of the wires and a width substantially equal to three times the diameter of the wire. These grooves are spaced relative to one another in the same manner as the wire receiving and positioning guide slots 112 of the guide members 110 shown in FIGURE 3.

(l'he end portions of brushes 40 where the contact wires are soldered together are placed in a groove on surface 34. The wires may then be secured in the grooves by a suitable non-conducting epoxy-adhesive capable of bonding metal to phenolic and phenolic to phenolic. Such adhesives are commercially available and wellknown in the art. Cover plate 29 may be placed over the protruding V portions of brushes 40 and secured by the same adhesive on surfaces 34 over the ends 23 of brushes 40.

Metal support post members 114 may then be cut off from the ends of the contact brushes 23 along lines 240 of FIGURE 1 at each end of the brush assembly.

As a result of this step, each brush 40 becomes electrically separate, though the three wires forming each brush remain electrically connected together by the portion of the solder connection made .at each end of the brush assembly and applied along the wires when they were originally soldered to post members 114. Post members 114 are not used in the brush assembly and may thus be discarded. The ends 23 of brushes 40 may be connected to various other conductors in any conventional manner.

Advantages of the foregoing method over methods used heretofore reside in producing multiple brush contact assemblies where the brushes are electrically separate, and yet at the same time each brush is composed of a plurality of electrical conductors which are secured together. To produce a multiple wire brush having the desired operating characteristics, each wire must be bent to have identical con-tours. By the present invention the wires used to form each brush are soldered at one end and then permitted to droop freely across the jig as determined by the natural curvature of the wire when the lengths of wire are cut from the coil rather than being stretched taut as in prior methods, before the other end is soldered. The cylindrical outer surface .104 on jig base 102 and slots 11-2, in guide members 110 facilitate the proper disposition of the lengths of wire so that each will have the same initial length and proper orientation.

.In the method of the present invention, support posts 1-1 4 are throw-away metal strips used solely for initially positioning the several brushes and wires forming each brush. .The solder applied to post 114 is caused to run along the wires away from post .114. After the V-shaped contacts are formed, the brush sub-assembly is positioned on the base of brush contact assembly and the several brushes secured thereto by an adhesive which may have insulation proper-ties. After the adhesive has hardened, the throw-away support posts are cut off to thus electrically isolate the several brushes of the brush contact assembly one from the other, but yet the individual wires of each brush remain soldered together at both ends.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiment is therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

What is claimed and desired to be secured by United States Letters Patent is:

1. A method of manufacturing a contact brush assembly having a plurality of brushes, each composed of a plurality of individual wires connected electrically together and secured to spaced support members of insulating material comprising the steps of: providing a pair of spaced parallel post members having an upper solderable metal surface; placing lengths of wires across the upper surfaces of said post members in a predetermined pattern; soldering the wires to said post members and the individual wires of each contact brush to each other while in said predetermined pattern to form a subassembly, the solder being applied along the wires from the position on the post member toward the center of the contact brush a predetermined distance; bending the wires to form V shaped contact portions at a central position of each contact brush; placing said sub-assembly over said spaced support members of insulating material; securing opposite ends of each individual contact brush to said support members at positions approximately where the individual wires of each brush are secured together; and finally cutting the wires on an end at a position between said support members and said post members to remove a post member from the contact brush assembly, said cutting occurring within said predetermined distance, whereby a substantial portion of the bonded connection is left intact at least at one end of each group of wires.

2. A method of manufacturing a contact brush assembly having a plurality of brushes, each composed of a plurality of individual wires connected electrically together and secured to spaced support members of insulating material comprising the steps of: providing a base member having an upper surface and parallel spaced slots formed in said upper surface; placing elongated post members having upper metal surfaces in said slots; placing lengths of wires across the upper surfaces of said post members in a predetermined pattern; securing the Wires to said post members and the indivdual wires of each contact brush to each other by an electrically conducting bonding agent while in said predetermined pattern to form a sub-assembly, the bonding agent being applied along the wires from the position on the post members toward the center of the contact brush a predetermined distance; removing the sub-assembly thus formed from the base member by removing said post member from said slots; bending the wires of said sub-assembly to form V shaped contact portions, at a central position of each contact brush; placing said sub-assembly over said spaced support members of insulating material; securing opposite ends of each indivdual contact brush to said support members at positions approximately where the individual wires of each brush are secured together; and finally cutting the brushes on an end at a position between said .support members and said post members to remove the post members from the contact brush assembly, said cutting occurring within said predetermined distance, whereby a substantial portion of the bonded connection is left intact at least at one end of each group of wires.

3. A method of manufacturing a contact brush assembly having a plurality of brushes, each composed of a plurality of individual wires cut from a coil of wire having a predetermined diameter and connected electrically together and secured in parallel relation at opposite ends to spaced support members of insulating material comprising the steps of: providing a base member having an upper surface with elongated slots formed therein such that the longitudinal axes of said slots are parallel; placing elongated post members having upper metal surfaces in said slots; said slots orienting said post members such that said upper metal surfaces are parallel to the free position of wire lengths placed thereon which are cut from said wire coil of predetermined diameter; freely placing lengths of wires cut from said coil of wire across the upper surfaces of said post members in a predetermined pattern; securing the wires to said post members and the individual wires of each said predetermined vpattern to form a siib-assembly,'the bonding agent being applied toeachjend of the wires along the wires toward the center of the, contact brush a predetermined distance; removing the sub-assembly thus formed from 'saidbase member-by removing said post members from said slots; bending the Wires of said contact brush assembly to form'V shaped contact portions at the center of each wire; placingsaid sub-'assernbly'over spaced support members of electrical insulating material; securing opposite ends of each indiviual contact-brush to said support members at positions approximatelywhere the individual wires of each brush; are soldered together; and finally cutting the wires'on an end at a position between said support members and said postmembe'rs to remove a post member' fromthe contact brush assembly, said cutting occurring within said predetermined distance, whereb'y'a substantial 'portionof the bonded connection is left intact at least atone end of each group of wires.

4. A method of manufacturing a contact-brush assembly having a plurality of brushes,1each composed'of a plurality of individual wires cut from a;coil of wire'havv ing'a predetermined diameter, which are connected electricallyj together and each secured to parallelsup'port' members of insulating material comprising the steps ,of:

providing a base member with anupper-surface having a radius'of'curvatu're corresponding to the radiusof curvature of saidtcoil-of wire; elongated-slots havinglparallel axes, and wire guide memberspositioned near and"par-,

allel to a corresponding slot,ysaid wire" guide members having spaced guide slots'with the bottom of said guide slots lying-substantially flush with said upper curved'surface; placing elongated post members having uppermotallic surfaces in said elongated-slots such that the upper contact brush :to' each other by an electrically conductingbonding agentwhile in tionsat the center of eachwire;'placing said sub-assembly over said spaced support; members of insulating material and' securing opposite ends of each individual contact brush to said support member, at positions'approximately where the individual wires of each brush are secured together; and finally cutting the wires off atan end at a position between said support members and said post members to remove a post member from the contact brush assembly said cutting occurring .within' said predetermined 'distance, whereby;a substantial portion'of the bonded connection is left-intact at least atone end of each group of wires.

5.A method-of manufacturing a contact brush assembly having a plurality of ibrushes, each composed of a plurality of individual wires connected electrically together and secured to spaced support members of insula'ting material comprising the steps of: providing a pair 7 of spaced parallel postmembers; placing lengths of wires across the-upper surfaces of said post members in a predetermined pattern; forming a sub-assembly'by securing I thewires to said post members and the individual wires of each contact brush to' each otherwhile in said predetermin'e'd pattern by means of an electrically-conductivevbonding agent, the bonding agent being applied along the wires from the position on the post member toward the center of the contact brush a predetermined distance;

bending the wires to form V. sh'apedcontact portions at metallic surface's o'f saidpostmembers are substantially flush with said upper curved surface of said base member;

post members from: said elongated slots;" bending the, Wires of said sub-assembly-to form'V-shapedcontact pora central position of each contactbrush; placing said sub-assembly lover said sp'acedsupporttmembers of insulating material; securing opposite vendsgof each individual contact brush to said support members at positionsapproximately where the individual wires of each brush are secured together; and finally cutting the wires on an 'end' at a position between'said support members and said post members to remove a *post member from the contact brush assembly, said cutting'occurring within said predetermined distance whereby a substantial portioriof the-bonded connection is left intact at least at one end of each group of wires.

References Citedjby the Examiner v UNITED STATES. PATENTS 2,699,133

WHITMORE WILTZ, Primary Examiner;

JOHN F. CAMPBELLg Examiner. j I

Claims (1)

1. A METHOD OF MANUFACTURING A CONTACT BRUSH ASSEMBLY HAVING A PLURALITY OF BRUSHES, EACH COMPOSED OF A PLURALITY OF INDIVIDUAL WIRES CONNECTED ELECTRICALLY TOGETHER AND SECURED TO SPACED SUPPORT MEMBERS OF INSULATING MATERIAL COMPRISING THE STEPS OF: PROVIDING A PAIR OF SPACED PARALLEL POST MEMBERS HAVING AN UPPER SOLDERABLE METAL SURFACE; PLACING LENGTHS OF WIRES ACROSS THE UPPER SURFACES OF SAID POST MEMBERS IN A PREDETERMINED PATTERN; SOLDERING THE WIRES TO SAID POST MEMBERS AND THE INDIVIDUAL WIRES OF EACH CONTACT BRUSH TO EACH OTHER WHILE IN SAID PREDETERMINED PATTERN TO FORM A SUBASSEMBLY, THE SOLDER BEING APPLIED ALONG THE WIRES FROM THE POSITION ON THE POST MEMBER TOWARD THE CENTER OF THE CONTACT BRUSH A PREDETERMINED DISTANCE; BENDING THE WIRES TO FORM V SHAPED CONTACT PORTIONS AT A CENTRAL POSITION OF EACH CONTACT BRUSH; PLACING SAID SUB-ASSEMBLY OVER SAID SPACED SUPPORT MEMBERS OF INSULATING MATERIAL; SECURING OPPOSITE ENDS OF EACH INDIVIDUAL CONTACT BRUSH TO SAID SUPPORT MEMBERS AT POSITIONS APPROXMIATELY WHERE THE INDIVIDUAL WIRES OF EACH BRUSH ARE SECURED TOGETHER; AND FINALLY CUTTING THE WIRES ON AN END AT A POSITION BETWEEN SAID SUPPORT MEMBERS AND SAID POST MEMBERS TO REMOVE A POST MEMBER FROM THE CONTACT BRUSH ASSEMBLY, SAID CUTTING OCCURRING WITHIN SAID PREDETERMINED DISTANCE, WHEREBY A SUBSTANTIAL PORTION OF THE BONDED CONNECTION IS LEFT INTACT AT LEAST AT ONE END OF EACH GROUP OF WIRES.

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