US3416225A - Method of assembling a relay - Google Patents

Description

DEC. 17, T. R. WELCH METHOD OF ASSEMBLING A RELAY Filed Oct. 18, 1963 2 Sheets-Sheet l .z'wswoe Dec. 17, 1968 T. R. WELCH METHOD OF ASSEMBLING A RELAY Filed Oct. 18, 1963 2 Sheets-Sfieet 2 Mai 4 m a; w 0 M 5 w a a j a a w :m /M M m IVVEUIZ United States Patent 3,416,225 METHOD OF ASSEMBLING A RELAY Thomas Ross Welch, Los Angeles, Calif, assignor to Welch Relay Company, Inc., Los Angeles, Calif., a corporation of California Filed Oct. 18, 1963, Ser. No. 317,366 26 Claims. (Cl. 29-593) ABSTRACT OF THE DISCLOSURE A method of assembling a relay having a contact header with fixed and movable contact posts of cylindrical form including the steps of fabricating the header; fabricating a pair of fixed contacts each of resilient ribbon metal of generally spiral form with a curled hub and a generally circumferential contact tip; fabricating a resilient movable contact blade with a hub curl at one end; locating the header in a jig so as to establish a datum axis by reference to which the contact positions can be established; providing test circuit connections to some of the contact posts; adjusting the movable contact to an unstressed position with its blade in contact with the hub of a respective fixed contact and fixing it in that position; and then rotating the normally closed contact to a position in which its blade is preloaded in a flexed condition and fixing it in that position.

Also, a method of assembling the magnetic subassembly of .a relay to a previously assembled contact and armature subassembly, by effecting relative movement between the subassemblies so as to mate them; then further moving the magnetic-armature subassembly so as to reverse the contact positions; and then securing the subassemblies together in a positional relation thus determined.

This invention relates to relays of the type wherein an armature embodies actuator means engageable with one or more movable relay contacts to shift it or them away from a respective fixed contact or contacts on which they are normally closed into engagement with an opposed, normally open contact or contacts. The principal object of the invention is to provide an improved method and apparatus for expeditiously fabricating such a relay in quantity with a high level of accuracy and precision in the positional relationships of the assembled parts, and a high degree of dependability and serviceability in the fabricated relay, A corollary object is to provide a relay of improved design contributing to the attainment of said principal object by facilitating the assembly procedures of the invention.

A rapidly increasing demand for high precision relays and other electrical components of micro-miniature proportions, especially adaptable for service in missiles and other vehicles where reduction in weight is a prime requisite, has developed a corresponding and pressing need for improved methods of fabricating such miniaturized electrical components expeditiously. The minute dimensions of the operating parts of miniature relays (in the range of less than .8 inch outside envelope dimension) create extreme difiiculty in the manipulation, assembly and adjustment of such minute parts, which operations must necessarily be performed by hand labor. Such problems are aggravated in the case of a double-pole, doublethrow relay having two sets of fixed contacts and two movable contacts in an assembly wherein the positional relationships between the fixed contacts (normally open and normally closed) of each pair and its respective movable contact, must be precisely adjusted to tolerances measured in the ten thousandths of an inch, and in which the limit positions of one movable contact must be precisely correlated with the limit positions of the other movable contact because a single device (e.g. armature) Patented Dec. 17, 1968 is utilized in simultaneously actuating both of the movable contacts.

The present invention contemplates the fabrication of a relay the maximum dimension of Which may be less than /1' inch, wherein contacts may be of considerably less than /2 inch length, and in which some of the smaller parts are of almost microscopic proportions. With the foregoing in mind, the invention embraces the following objects:

(1) To provide a method whereby a plurality of prefabricated parts and/or sub-assemblies are simultaneous- 1y assembled, adjusted as to position, tested for correct positions, and fixed in such correct positions by direct reference to the test indications during the testing procedure;

(2) To provide an improved method and means of adjusting, testing and holding first one pole piece and then the other pole piece of a magnet with reference to the respective ends of the armature and the respective sets of contacts actuated thereby, and then fixing the magnet to preserve accurately the adjustments at both ends thereof;

(3) To provide an improved method of relay assembly wherein relay contacts are adjusted and fixed in position with reference to a datum line established in relation to the contact mounting; and in which the subsequent step of positioning the armature and magnet in correct relationship to the contacts, is again effected with reference to the same datum line;

(4) To provide an improved method of adjusting, testing and then fixing a first pair of fixed contacts with respect to a double-throw cooperating movable contact and a contact-mounting header;

(5) To provide an improved method of adjusting, testing and fixing a :second pair of fixed contacts in a correct relationship to their common double-throw movable contact and to the first set of contacts in relation to a common mounting header, and also with reference to a double-ended armature and its actuator fingers, so that the two sets of contacts will be properly actuated in unison by said armature;

(6) To provide a relay having fixed contacts especial- 1y designed for facilitating precise assembly and testing operations;

(7) To provide a relay comprising fixed and movable contacts, a swinging armature carrying an actuator projection for actuating a movable contact, and a magnet having a pole piece in opposed relationto the armature, in an arrangement which facilitates the precise assembly operations of the invention.

Other objects and advantages will become apparent in the ensuing specification and appended drawing in which:

FIG. 1 is a perspective view of a relay embodying the invention;

FIG. 2 is an exploded perspective view of the several units of the relay;

FIG. 3 is a perspective view of the relay armature;

FIG. 4 is a front elevational view of the assembly apparatus with a relay positioned therein, and of the welding head;

FIG. 5 is a plan view of the relay assembly positioned in the assembly jig;

FIG. 6 is a view, showing, of contacts in the relay and schematically showing the testing circuit and the contact assembly jig;

FIG. 7 is a plan view of one of the fixed contacts of the relay; and

FIG. 8 is a cross-sectional view of the same, taken on line 8-8 of FIG. 7.

Referring now to the drawings in detail, I have shown therein, by way of an example of the invention, a doublepole, double-throw type relay comprising, in general, a

in plan, the arrangement contact assembly A, a double ended swinging armature B, an electromagnet C with pole pieces at respective ends thereof; and a frame D on which units B and C are mounted. FIGS. 4 and 5 disclose the final assemble jig E in which the units of the relay assembly are positioned and adjusted and tested and finally welded together in order to fix their adjusted relationship. FIG. 6 shows schematically the jig F in which the contacts are fixed in position on their mounting header.

DESCRIPTION OF RELAY Contact assembly A comprises a contact header 10 of rectangular shape, pairs of fixed contact mounting posts 11, 12, and 11, 12' fixed in the respective ends thereof and projecting upwardly, pairs of fixed contacts 13, 14 and 13, 14' each having one end mounted on a respective contact mounting post; a pair of movable contacts 15. 15', and a corresponding pair of mounting posts 16, 16' on which the ends of the movable contacts 15, 15' are respectively mounted. Posts 11, 11', 12, 12, 16, 16, project below the header 10 to function as terminals 11a, 12a, 16a (FIGS. 1 and 2) when the relay is later connected into a circuit.

The mounting posts 11, 11, 12 ,12', 16, 16 are mounted to the header 10 by means of respective sleeves 17 of insulating material such as ceramic or glass. Thus, the header 10 may be of metal. The sleeves 17 are mounted in circular apertures in the header 10 and secured thereto by suitable glass-to-metal bonds, using known techniques.

In the forward and rearward margins of header 10 are locating recesses 19 which are open upwardly and laterally but have closed bottom shoulders 18.

Each of the fixed contacts 13, 14, 13', 14 comprises a cylindrical hub collar 20 in the form of an integral roll on one end thereof, a body 21 joined integrally to a respective hub collar 20 at one end thereof and extending therefrom on a high-rise spiral contour, and a contact portion 22 extending from the body 21 on a low rise spiral contour and terminating in a clearance tip 23 of decending spiral form. As shown in FIG. 8, the contact tip 22 has a double curvature, being curved transversely as well as longitudinally, so as to make substantially spot contact with a respective switch blade 15 or 15. The design of the relay is such that the tip 22 will be in position for electrical contact with the respective switch blade when the parts are assembled, adjusted and fixed in position. The contact tip 22 is adapted to be engaged by a respective switch blade 15 or 15, at a point which is determined by the adjustment of the respective fixed contact on its respective mounting post. Such adjustment, effected during assembly of the relay, consists of swinging the respective contact arcuately around its respective mounting post, with the hub collar 20 functioning as a bearing turning upon the respective post.

Each of the movable contact blades 15, 15 includes a movable shank portion 27, 27' terminating in an integral, rolled hub collar 28 which encircles a respective mounting post 16, 16. This makes it possible to adjust the position of the blade between a pair of fixed contacts during the assembly and adjustment of the relay. The shank 27 and the blade 15 are bent in an obtuse angular relation such that the blade 15 will extend substantially along the longitudinal axis of the panel 10 while the shank 27 is inclined outwardly away from that axis to the post 16 which is spaced laterally from the axis. As the permanent positions of the switch blades 15, 1'5 and the fixed contacts 13, 14, 13', 14', are determined, hub collars 28, are secured to their respective mounting posts by silver soldering =(or welding or other equivalent securing means).

Referring now to FIG. 7, the high rise spiral of contact body 21 terminates approximately at the position designated by the broken line a, the low rise spiral contact portion 22 commences at that point and terminates approximately at the point designated by the broken line b, the longitudinal curvature of the contact becoming substantially concentric with the axis of its mounting post at the point b, and the descending spiral curvature of tip 23 commences at the point b and continues to the end of the contact. It may now be noted that the low rise spiral curvature of contact portion 22 provides for a fine adjustment in the radial shifting of the contact position as the contact element is rotated, the contact position shifting circumferentially between the points a and b with tangency between the flat surface of blade 15 or 15 and the curvature of contact portion 22 in each such position. The high rise body portion 21 provides for a high rate adjustment from a backed off position to a contact position approaching a predetermined final adjusted contact position. Also, the body portion 21 and the contact portion 22 between the point a and the finally adjusted contact position, provide a circumferential extent of resiliency in the contact element between its point of rigid attachment to its mounting post and the contact position, such as to provide a cushioning action in the contact element under the impact of the contact blade 15 against it during relay operation, which cushioning action reduces the tendency of the blade 15 to bounce against the contact portion 22. The blade 15 of course is likewise resilient, this added resiliency further reducing the tendency to bounce. In operation, the two contacts, after initial engagement with one another, tend to follow each other in any vibration induced in the respective contacts by the impact, and to retain full electrical contact without rebound such as would result in temporary minute separation and arcing.

Armature B which may be a coined part of soft iron, embodies a central hub portion having acylindrical bore, journalled upon a pivot pin 36 carried by frame D; a pair of actuator arms 37, 37' of wedge shape projecting in opposite directions from hub 35 adjacent a longitudinal axis intersecting the axis of pivot pin 36; and a pair of actuator fingers (FIG. 3) extending downwardly from the respective arms 37, 37', said fingers comprising respective stalks 38, 38' each of which may consist of a short length of metal wire secured at one end to a respective arm 37, 37' and having at its other end a rounded actuator tip 39, 39 consisting of a bead of insulator material such as ceramic or glass, bonded onto the free end of the respective stalk.

The armature arms 37, 37' have fiat abutment faces 40, 40' disposed in parallel planes only slightly spaced on respective sides of the pivot axis, and adapted to make abutting contact with respective pole pieces of magnet C. Abutment face 40 has a length somewhat less than that of 40' limited by confinement within its respective pole piece, whereas the length of face 40 is not thus limited since it engages the external side of its pole piece. The wedge shape of the arms 37, 37 concentrates the weight of the armature toward its pivot axis, and the arm 37, though longer than arm 37, is of a thinner taper and the arms are substantially balanced against one another so as to minimize amplitude build-up in the oscillatory vibration of the armature. The taper of arm 37, which has only a thin edge adjacent the transverse portion of its respective pole piece, minimizes leakage of magnetic flux between the tip of the transverse portion of the pole piece. Also, this taper provides ample room for the tilting movement of the arm 37 between the pole piece and the adjacent side of the armature coil.

In the abutment face 40 of arm 37 is a shallow springseat recess 41, in which is seated the base of the frustoconical return spring 42 the outer end of which is engaged under compression against an abutment car 43 on frame D.

A snap ring 44 is received in an annnular recess near the outer end of pivot pin 36 to retain the armature 37 in position seated on an annular shoulder provided by an enlarged head 45 on the lower end of the pin 36, said head being staked into an aperture in frame D.

Electromagnet C comprises a soft iron cylindrical rod core 50 and respective pole pieces 51 and 52 of L-shape having respective parallel mounting arms provided with apertures in which are staked reduced necks 53 on the respective ends of core rod 50, and having respective pole heads 54, 55 positioned for abutting engagement by the abutment faces 40, 40' of the armature B, on opposite sides of the armature. The pole pieces 51, 52 are fabricated of soft iron in fiat bar form, and have undersides seated flatly against the upper surface of frame D and welded thereto as set forth more specificaly hereinafter.

A magnet coil 56 is wound about core 50 and retained between the end arms of pole pieces 51, 52. The pole head 54 is spaced forwardly of coil 56, armature arm 37 being movable in the space between head 54 and the coil; and coil head 55 is positioned closely adjacent the coil 56 at the opposite end thereof.

A terminal 57 is fixed in the contact header and projects upwardly for connection to one end 56' of coil 56. A terminal 58, for connection to the other end 56' of coil 56, is mounted in an insulator bead 59 which in turn is mounted in an aperture in header 10. Terminal 57 is offset rearwardly and thence projects upwardly between the armature arm 37 and coil 56.

Frame D is of stamped non-ferrous sheet metal comprising a fiat rectangular body 60 having the head 45 of armature pivot pin 36 staked into a circular aperture therein adjacent its forward side and substantially midway between its ends; having the spring abutment car 43 struck upwardly from an aperture adjacent the pivot pin 36 and disposed in the vertical plane of its forward side; having an aperture 61 extending substantially full width from front to rear on the left-ward side of car 43; having a smaller rectangular aperture 62 adjacent its forward side on the rightward side of pivot pin 36; having an end web 63 providing a seat for the pole piece 51; having an armature stop finger 64 integral with and bent upwardly from the inner margin of web 63 at the leftward side of aperture 61; having a rightward end web 65 providing a seat for the pole piece 52; having respective dimpled welding projections 66 and 67 embossed upwardly in the respective end webs 63 and 65; and having pairs of feet 68 .and 69, integral with and bent downwardly from the respective forward and rearward margins of the frame, the four feet being provided with inwardly embossed welding projections 70 for attachment to a support. Rearward feet 69 are formed as integral bottom corner portions of a skirt 71 extending along the rearward margin of the frame. The wider rearward end of aperture 61 is extended downwardly into the skirt 71 at 72, and the rightward forward corner portion of aperture 62 is extended downwardly into the rightward leg 68 at 73. The rear opening 72 facilitates the attachment of the end of coil 56 to terminal 58. The front opening 73 provides clearance for the actautor bead 39 to enter the frame during the assembly of the armature 40 to the frame D.

THE ASSEMBLY APPARATUS AND METHOD OF ASSEMBLY Assembly jig F (as shown in FIG. 6 as an example) comprises a suitable socket part 87 having a plurality of electrical connector sockets (not shown) positioned to receive the terminal tails 11a, 12a and 16a, so as to establish connections to the test circuit 90, 91, 92, etc. Socket part 87 may be loosely mounted in a retainer recess 89' of a jig base 89 having a diagonally opposed pair of fixed locating stops 88 receivable in locating recesses 19 of header 10. The lose mounting of socket part '87 in retainer recess 89 may be such as to permit sufiicient clockwise shifting of base 10 and socket part 87 to clear the ends of fixed locating projections 88 for insertion of the projections into recesses 19. A pair of spring-loaded locating plungers 88, suitably mounted in jig base 89, may be withdrawn during such insertion step and may then be released for spring-energized projection into the two diagonally opposite alternate recesses 19, and will thereafter function, throughout the contact-fixing operation hereinafter described, to hold the header 10 accurately located against the fixed stops 88, with the inner walls of recesses 19 snugly pressed (by the springloading) against the ends of stops 88. Thus a datum line for the subsequently fixed assembly of contacts, is accurately established in fixed relation to header 10 and recesses 19.

Other equivalent means for locating the header in an assembly jig having test-circuit connections, may be utilized.

Preparatory to fixing the positions of the relay contacts, the contact assembly A is mounted in assembly jig F as hereinbefore described.

Positioning of movable switch blades 15, 15' is effected by backing off their normally closed contacts 13, 13 in a counterclockwise direction to positions corresponding approximately to that shown in phantom for the contact 13, where their tips 23 will clear the respective switch blades 15, 15'. The blades 15, 15' are then rotated on their mount ing posts 16, 16' until their free ends establish cont-act with the respective hubs 20 of their normally closed contacts 13, 13' or otherwise establish initial unstressed positions of predetermined spacing from the axes of contacts 13, 13' inwardly of the radius of their contact portions 22; and the hubs 28 of the blades 15, 15' are then silver soldered (or *welded or otherwise suitably secured) to their respective mounting posts 16, 16'. The contacts 13, 13' are then successively rotated back to their operative positions shown in full lines, as more fuly described in the next paragraph, thus flexing the respective switch blades 15, 15' to establish a predetermined correct amount of preload in the blades. Where the blades 15, 15 are of relatively high flexibility, their unstressed positions are satisfactorily determined by actual contact of blades 15, 15 with hubs 20. For stiffer blades, the initial, unstressed positions can be established by means of a spacer of predetermined thickness inserted between a hub 20 and a respective blade 15, (15'); or by contact of blade 15 (15) against a selected spot on rising spiral portion 21 of the respective contact 13 (13') which spot can be referenced to a predetermined degree of rotation of contact 13 (13') from a selected starting position. The preload in blade 15 (15') is determined by the amount of rise from the starting position to the operative position of contact 13 (13').

Attachment of fixed contacts Preparatory to adjustment of the contacts 13, 13' to their operative positions as decribed above, the various contacts of the assembly are connected to a test circuit (e.g. through socket part 87). One side of such test circuit has parallel connections 90 to the movable contact posts 16, 16' and the other side has parallel connections 91, 91' to the normally open contact posts 12, 12' through indicator lamps 92, 92'. The correct operative positions of normally closed contacts 13, 13 are established during the above described rotary adjustment of these contacts when the respective indicator lamps 92, 92' are lighted. At that point, in each adjustment the rotation is stopped and the contacts 13, 13', in succession, are silver soldered or otherwise secured to their respective mounting posts 11, 11', and are thereby fixed in their positions thus established.

It will now be apparent that the rotary adjustment of normally closed contacts 13, 13' from their backed-off positions to the point where the indicator lights are lighted, simultaneously establishes (1) the correct amount of preload in the movable switch blades 15, 15' and (2) the correct operative positions of the normally closed contacts.

The position of each contact 14 (14') is established by rotating the respective contact on its respective post 12 (12') to a backed-off position, inserting a spacer blade 93 of predetermined thickness between the respective contact 14 (14) and the respective switch blade 15 (15) and then rotating the contact 14 (14') back to its operative position as determined by its first contact with the spacer blade 93 as indicated by the lighting of the indicator lamp 92 (92). This step establishes the correct amount of spacing between the switch blade and its normally open contact 14 (14') and the latter contact is then fixed to its respective mounting post 12 (12) by silver soldering or equivalent securing means. It may be noted that in determining the positions of contacts 14 (14') as indicated by the lighting of the respective indicator light, the spacer blade 93 provides a conductive connection between the switch blade 15 (15) and contact 14 (14') to close the circuit to the respective indicator light.

During the process of locating and fixing the several contacts to the header 10, the latter may be located in the jig F by engagement of locating lugs 88 of the jig F in marginal notches 19 of the header 10. Thus, the positions of the several contacts may be established with reference to a datum line extending longitudinally of header between the respective pairs of fixed contacts (e.g. approximately the major longitudinal axis of the header 10). Subsequently, the positioning of the other parts of the relay relative to the header 10 may likewise be established with reference to this datum line as hereinafter described.

Jig F may optionally include suitable welding apparatus generally similar to that shown in FIG. 4, hereinafter described, for securing the contacts by welding in lieu of soldering.

During such welding operations on contact assembly A, the lower electrodes may be connected, through a suitable connector unit such as socket part 87, to the several tails 11, 12, 16 etc. while the upper electrodes are, in sequence, adjusted to engage the various contact parts on the upper side of assembly A.

Having completed the assembly of the contacts to the header 10, the operator has achieved an assembly in which each pair of contacts is properly spaced by the measuring action of the interposed spacer blade 93 in which the proper amount of preload has been established in the switch blade (15') by its initial positioning behind its final position and the subsequnt flexing of the blade to its final position by the rotational positioning of the backedofi normally closed fixed contact 13 (13') to its operative position. This assembly is then conditioned for proper positioning in the remainder of the relay assembly by reference to the positioning recesses 19 in the sides of the header 10, and the datum line related thereto.

Assembly of actuator fingers to armature Preparatory to the next stage of assembly, the actuator knobs are secured to their respective armature arms 37, 37 by placing the knobs in a fixture designed to receive and locate the knobs 39, 39 the stalks 38, 38', and the armature body with its respective arms 37, 37' lying across the respective stalks 38, 38 in exactly the correct positional relationship to one another and in relation to the datum lines of mating parts, the armatures pole contact faces 40, 40 being brought against stops in the fixture. A welding electrode is then brought to bear against the top of the armature body, suit-able welding pressure is applied, and a pulse of welding current is then sent through the assembly (the fixture functioning as the bottom electrode) so as to weld the stalks to the undersides of their respective armature arms in correct positional relationship. The excess lengths of the stalks are then snipped off.

The welding apparatus may be generally similar to that utilized in the next stage of assembly and shown in FIG. 4, including a welding head 95 carrying a pair of depending, adjustable welding electrodes 96 for delivering welding current from one side of a welding circuit for which the jig base 95 has spaced lower electrodes 96 on which the ends of frame D may rest and thus establish contact for the other side of the welding circuit.

In the next stage of assembly, the completed armature is mounted on its vertical pivot 36 on its frame D which is now assembled on the contact base A by dropping the locating lugs 68, 69 into their recesses 19 of the base A, and immediately welding the lugs to the base. Previously, the actuator knobs were positioned properly with respect to their respective armature arms in the intermediate stage described above. The magnet is superimposed upon the armature frame and temporarily left in a loose, unattached condition, final assembly being attained by adjusting the position of the magnet. This loose assembly is then placed in the assembly jig E of FIG. 4.

The assembly jig E (FIG. 5) comprises a channel shaped base having forward and rearward walls 76, 7'7 projecting upwardly from its forward and rearward margins respectively; a magnet positioning yoke 78 fulcrummed on a pivot pin 79 projecting upwardly from base 75 and having, at its respective ends, arms 80 posi tioned for embracing engagement against the respective ends of magnet C; an adjustment screw 81 threaded through the rightward end portion of forward wall 76 and engageable with armature arm 37'; a spring loading button 82 mounted slidably in a bore 83 in the opposite end portion of Wall 76 and loaded by a coil spring 84 in the bore 83, into yielding pressure engagement with the pole head 54 of the magnet C, the spring 84 being seated under compression against a retainer cap screw 85 threaded into the wall 76 at the forward end of bore 83; and a compression spring 86 engaged under compression between the rightward end of wall 77 and the rightward end of magnet-positioning yoke 78.

It may be noted at this point that the coil spring 86 tends to tilt the magnet holder 78 and the magnet C clockwise as viewed from above in FIG. 5; the spring-loaded plunger 82 tends to shift the leftward end of magnet C clockwise in the holder 78; and the adjustment screw 81 is operable counterclockwise, to oppose such spring-loaded shifting.

The loose assembly of base A, armature B, electromagnet C and base D is fitted into jig E in approximately the positions shown in FIG. 5, but with the screw 81 initially backed off to provide clearance space to receive arm 37'. The adjustment screw 81 is operable, firstly, to move the armature B counterclockwise against the resistance of its return spring 42 until its abutment faces 40, 40 establish contact with the respective pole heads 54, 55, and is then further operable to apply counterclockwise pressure to the rightward end of magnet unit C, transmitting the pressure through the arm 37, to the pole head 55. The jig E is mounted in (or incorporated in) a welding apparatus such as that shown in FIG. 4 and previously described herein, the ends of frame D being supported on the lower electrodes 96' as indicated in FIG. 4, and the upper electrodes 96 being adjusted to proper positions to engage the pole pieces 51 and 52 of electromagnetic unit C. The terminals 11, 12, 16, etc. of contact assembly A are connected to the indicator light circuit previously described (or a similar one). The upper electrodes 96 are brought down against the respective poles 51, 52 of the magnet assembly, and light clamping pressure is applied. The welding fixture will initially hold magnet unit C and armature B in a limit position of clockwise rotation in response to the spring loading applied clockwise by springs 84 and 86 against respective ends of the assembly on opposite sides thereof. The positions of upper and lower electrodes 96, 96' is shown in FIG. 6, though the remainder of the welding apparatus is omitted. The pivotal movement of the assembly is effected about the vertical axis of the armature pivot 36. Micrometer screw pressure is then applied by screw 81 to the one end of the armature opposite the spring loading, and the armature is gradually moved to establish contact of its pole faces 40, 40' with their respective pole pieces, the magnet unit C being free for limited shifting in its positioning yoke 78 as required to establish full contact between both armature arms 37, 37 and their respective pole pieces. The armature and magnet are rotated about the armature axis until the lighting of an indicator light indicates that an actuator knob of the armature has moved the switch blade at that point to an initial operating position in which it is barely touching its normally open contact.' Both ends of the assembly are tested for the initial contact position and there are separate indicator lights to indicate this initial contact at both ends of the assembly. Normally it is expected that both indicator lights will come on simultaneously, indicating that both switch blades 15, 15 have closed on their normally open contacts 14, 14'. The proper amount of overtravel of the switch blade with respect to its normally open contact is now established by rotating the micrometer screw an additional distance determined by micrometer reading. This overtravel is often referred to as contact gram pressure.

These adjustments have taken place against the frictional resistance of the welding electrodes clamped against the respective pole pieces, and when the proper overtravel position is established, the assembly will be held in that position by the frictional clamping action of the electrodes while the micrometer screw is backed off to effect a backing off of the armature under its return spring load, thus preventing any welding action taking place on the armature either in its pivot or between its face and its pole piece. Where the lights do not go on simultaneously, the overtravel is determined from the position determined by the second lighting. Because of the differential between the two lighting positions, the contact first established will be given an extra amount of overtravel, which is actually advantages because it provides extra service life. The differential between contact establishing positions as between the two ends of the assembly, if it goes beyond a predetermined range, will be undesirable and upon determining it, the operator will reject the assembly and'return it for further processing beginning at the start of the process.

Having now established both initial contact positions plus the predetermined amount of overtravel, the welding current is turned on and the electrodes, already clamping the assembly in position, effect welds between pole pieces 51, 52 and frame D at the welding projections 66, 67, one at each end of the frame. The projections 67, projecting upwardly from frame D and engaged by the underfaces of the respective pole pieces, will thus weld the pole pieces to the frame and thereby properly position the magnet. In turn, the magnet properly positions the armature, transmitting positioning movement by engaging the contact faces 40, 40' against heads 54, 55 of the respective pole pieces throughout the adjusting movements.

The next assembly operation is one in which the coil terminals 56 and 56" are fastened to the respective terminals 57 and 58 by welding or other suitable attaching means.

An optional final assembly operation is to place a cover G over the entire assembly.

The invention has been described in the double-pole, double-throw embodiment, but is also applicable to other types of relays, having any number of poles and of singlethrow as well as double-throw type.

The invention contemplates the following possible modifications of the assembly and adjusting method described herein:

Instead of moving the armature into mating engagement with the magnetic unit C as described above, a reverse procedure wherein the magnetic unit is moved into engagement with the armature and these two units then moved in unison a further extent to a point where a reversal of the relationship of a pair of contacts is reversed (e.g. from closed to open relation or vice versa) and the parts subsequently secured in final assembly in a relationship determined with reference to the position at which such reversal occurs.

The fixing of the parts in the final relationship can be preceded by a step of further movement of the magnetic and armature portions of the relay in unison to an extent determined so as to establish a selected overtravel of the contacts.

A specific variation of the method may comprise the movement of the magnetic unit into mating engagement of a pole face thereof with the armature, and further moving the magnetic unit and the armature in unison to a position where normally closed contacts of the relay are open, such further movement being transmitted from the magnetic unit to the armature; and subsequently securing the magnetic unit and armature in a final assembly relationship determined with reference to such position where the contacts are opened.

The preceding variation of the method may include the additional step, preceding the fixing of the final assembly relationship, of effecting further measured movement of the magnetic unit and armature in unison to establish a predetermined contact gap between the normally closed contacts when in their opened positions.

Any of the above described methods, including one illustrated in the drawings, can be further varied by providing means for retaining the magnetic unit within fixed limits of movement with relations to the contact-armature subassembly so as to prevent completion of the assembly and adjusting operation where an undesirably large extent of adjusting movement would be required for such completion. This will avoid production of a relay that would be bad because of the excessive amount of adjustment required to bring a group of inadequately con formed parts into an apparently operable condition.

As a further variation of the method, a shim can be placed between the armature and an opposed face of the magnetic unit to determine a selected overtravel on normally open contacts of the relay; the magnetic unit and armature can then be brought together while the shim is engaged between them; and the magnetic unit and armature can then be moved in unison to a position wherein the normally open contacts are closed and at that position the parts can be secured in a fixed assembly having a correct relationship determined with reference to such position and the thickness of the shim.

In the variation described in the preceding paragraph,

the shim may be made of insulating material and may function to prevent any welding attachment of the armature to the magnetic unit in the step of welding the magnetic unit to the armature frame in order to fix the relationship between the parts.

As a further variation, of any of the methods described above, during the adjusting step wherein the magnetic unit is shifted to a fin-al position by movement received from the armature (or in which the armature is shifted to a final position by movement received from a magnetic unit) the correctness of the relationship estab lished between the relay parts including the contacts during this step (and during any subsequent step of moving the magnetic unit and armature beyond the position determined by reversal of contact relationship) can be measured by scanning the movement, utilizing suitable measuring techniques or indicating instrument to determine the external movement; and then securing the parts in the final assembly by reference to the measurements thus obtained.

I claim:

1. A method of assembling armature and magnetic parts of a relay to a previously fixed assembly of fixed and movable contacts mounted on a header, said movable contact being a blade attached to said header, engageable by said armature and projecting between a pair of said fixed contacts and preloaded in normally closed position against one contact of said pair, said method comprising: placing said fixed assembly of contacts into an assembly jig; locating said assembly in said jig in a determined relation to a datum line previously established; placing a magnet frame over said header and attaching it to said header; assembling an armature and magnet on said frame; effecting adjustment of said armature and magnet to shift said movable contact into initial engagement with the normally-open contact of said pair; utilizing such engagement to close an electrical indicator circuit for energizing an indicator device, whereby to determine the position of said initial engagement; and attaching said magnet to said frame in its adjusted position.

2. The method defined in claim 1, wherein said step of attaching the magnet is effected by welding to said frame in a position referenced to and determined by said position of initial engagement.

3. The method defined in claim 2, wherein said adjustment is a swinging movement transmitted from the armature to the magnet and is opposed by frictional clamping engagement of welding electrodes against pole pieces of said magnet, and wherein said clamping engagement is regulated so as to yield to pressure applied to said armature by positive movement means to effect said swinging adjustment and yet to hold said magnet in adjusted position.

4. The method defined in claim 3, including the step of holding the pole pieces in their adjusted positions while removing the armature from contact with the pole before welding.

5. The method defined in claim 4, wherein the action of a return spring, functioning in said relay to yieldingly bias said armature toward its normally closed position, is utilized to yieldingly oppose said swinging adjustment, the latter being effected by application of positive movement to said armature from an adjustable part of said jig.

6. A method of assembling a relay, including the following steps: fabricating a contact header having a pair of fixed contact'mounting posts mounted on the header and spaced from opposite sides of a datum axis, and having a movable contact mounting post, said contact posts all being of generally cylindrical form; fabricating a pair of fixed contacts of resilient ribbon metal each including a curled hub, a body integral with said hub at one end and extending therefrom in rising spiral contour, and a contact portion extending arcuately from the other end of said body on substantially a circumference of the axis of said hub; fabricating a movable contact comprising a strip of resilient ribbon metal having a hub curl at one end and at its other end a free flexible contact blade engageable with said contact portions of said fixed contacts; locating said header in a jig so as to establish said datum axis by reference to which the positions of said contacts can be fixed; establishing test-circuit connections to at least some of said contact posts; placing the hub curl of said movable contact and of at least one of said pair of fixed contacts over their respective posts; adjusting said movable contact to an unstressed position determined by engagement of the blade thereof against the hub of a respective normally closed fixed contact, with the body of the latter swung to a non-interfering position by rotation about its respective post; fixing said movable contact to its respective post while in said unstressed position; and then rotating said normally closed contact to a position in which said blade is flexed and thereby simultaneously preloaded by camming action of said contact body, and in which said contact portion of said normally closed contact is in normally closed engagement with said blade; and then fixing said normally closed contact to its respective post.

7. The method defined in claim 6, including the step of determining the position of normally-closed fixed contact engagement against said movable contact blade by energizing an electrical signalling device, utilizing said contact engagement to close the energizing circuit of said signalling device.

8. The method defined in claim 6, including the further steps of placing the hub of the normally open fixed contact over its mounting post in a position backed off from said movable contact blade; rotating said normally open contact around its respective post in a direction to utilize the rising spiral contour of its body to effect gradual approach toward contact with said blade; and determining an initial point of spacing between said normally open contact and said blade by engagement of a conductive spacer between said normally open contact and said blade, and the resultant energizing of an electrical signalling device in a circuit closed by such conductive engagement.

9. The method defined in claim 6, including the further steps of placing the fixed assembly of header and contacts into a final assembly jig; locating said header in said jig so as to utilize the aforesaid datum line previously established with relation to said header; placing an armature, magnet and frame over said header and attaching the frame to said header; effecting swinging adjustment of said armature to shift said movable contacts into initial engagements with their respective normally-open contacts; utilizing such engagements to close respective electrical indicator circuits for energizing respective electrical indicator devices, whereby to determine the positions of said initial engagements; determining the position of said magnet relative to said frame by reference to said positions of initial engagement; and fixing the magnet in the position thus determined.

16. The method defined in claim 9, wherein said magnet position is determined by utilizing swinging adjustment of the armature, transmitted to the magnet; and including the further step of continuing said swinging adjustment to a predetermined extent beyond said positions of initial engagements, for imparting selected resilient loading of said blades against their normally open contacts in the energized condition of the relay.

11. A method of assembling armature and magnetic parts of a relay to a previously fixed assembly of fixed and movable contacts mounted on a header, said movable contact being a resilient blade projecting between the contacts of a pair of said fixed contacts and preloaded in normally closed position against one contact of said pair, said method comprising: placing said fixed assembly of contacts into an assembly jig; locating said assembly in said jig in a determined relation to a datum line previously established; placing a magnet frame over said header and attaching it to said header; assembling an armature and magnet on said frame; effecting swinging adjustment of said armature and magnet to shift said movable contact into initial engagement with the normally-open contact of said pair; utilizing such engagement to close an electrical indicator circuit for energizing an indicator device, whereby to determine the position of said initial engagement; and attaching the magnet by welding to said frame in a position of said swinging adjustment referenced to and determined by said position of initial engagement of said contacts.

12. A method of assembling and adjusting the positional relationships of the magnetic portion of a relay to a previously assembled contact and armature subassembly thereof, including the step of effecting relative movement between said magnetic portion and the armature portion of said subassembly so as to mate said magnetic portion with said armature portion; then further moving said magnetic and armature portions in unison to a position in which the relationship of a pair of contacts of the relay is reversed; and subsequently securing said magnetic portion in fixed assembly with said subassembly in a relationship determined with reference to said position.

13. The method defined in claim 12, including the additional step of effecting further movement of said magnetic and armature portions of the relay to establish a selected overtravel of said contacts with reference to one another before effecting said fixed assembly; and wherein said fixed assembly is attained by securing the parts in the position in which said overtravel is established.

14. The method defined in claim 12, wherein a magnetic pole face of said magnetic portion is mated to an opposed face of said armature.

15. The method defined in claim 14, wherein said securing is effected by welding the magnetic unit to a frame member on which the armature is mounted, and including the further step of removing the armature from its mating engagement with the pole face of the magnetic unit prior to said welding step.

16. A method of assembling and adjusting the positional relationships of the magnetic portion of a relay to a previously assembled contact and armature subassembly thereof, including the step of moving the armature portion of said subassembly so as to mate it with said magnetic portion; then further moving said armature and thereby transmitting movement to said magnetic portion to a position wherein the relationship of a pair of contacts of the relay is reversed; and subsequently securing said magnetic portion in fixed assembly with said subassembly in a relationhip determined with reference to said position.

17. The method defined in claim 16, including the additional step of elfecting further measured movement of the said armature and magnetic portions of the relay in unison to establish a selected overtravel of said normally open contacts with reference to one another before effecting said fixed assembly; and wherein said fixed assembly is attained by securing the parts in the position in which said overtravel is established.

18. A method of assembling and adjusting the positional relationships of a magnetic portion to a previously assembled contact and armature subassembly of a relay having a pair of normally open contacts, including the step of effecting relative movement between said magnetic portion and the armature portion of said subassembly so as to mate said magnetic portion with said armature portion, then further moving said magnetic and armature portions in unison to a position where said normally open contacts are closed; and subsequently securing said magnetic portion in fixed assembly with said subassembly in a relationship determined by reference to said position.

19. The method defined in claim 18, including the additional step of effecting further measured movement of the magnetic portion of the relay to establish a selected overtravel of said normally open contacts with reference to one another; and wherein said fixed subassembly is attained by securing the parts in the position in which said overtravel is established.

20. A method of assembling and adjusting a magnetic unit to a previously assembled contact and armature subassembly of a relay having a pair of normally closed contacts, comprising the following steps: effecting relative movement between said magnetic unit and the armature portion of said subassembly so as to establish mating engagement of said magnetic unit with said armature portions; then further moving said magnetic unit and armature portion in unison until said normally closed contacts are open; and subsequently securing said magnetic unit in assembly with said armature and contact subassembly in a relationship determined with reference to the position achieved by said further movement.

21. The method defined in claim 20, including the additional step of effecting further measured movement of the magnetic unit to an extent such as to establish a predetermined contact gap between said normally closed contacts when in their open positions.

22. A method of assembling and adjusting the positional relationships of the magnetic portion of a relay to a previously assembled contact and armature subassembly thereof, including the step of moving said magnetic portion so as to mate the magnetic pole areas of said magnetic portion with said armature portion; then further moving said magnetic and armature portions in unison to a position in which the relationship of a pair of contacts of the relay is reversed; and subsequently securing said magnetic portion in fixed assembly with said subassembly in a relationship determined with reference to said position.

23. The method defined in claim 22, including the further step of retaining the magnetic unit within fixed limits of movement with relation to said subassembly so as to prevent the completion of the assembly and adjusting operation where an undesirably large extent of adjusting movement would be required for such completion.

24. The method defined in claim 22, including the further step of spring-loading the magnetic unit in a direction opposite to that in which it is adjusted to its final position in the assembly, and effecting said adjustment against the opposition of said spring-loading.

25. The method of assembling and adjusting a magnetic unit to a prevoiusly assembled contact and armature subassembly of a relay, comprising the following steps: placing a shim between the armature and an opposed face of said magnetic unit to determine a selected overtravel on normally open contacts of the relay; relatively moving the magnetic unit and the armature toward one another so as to engage the shim between the magnetic unit and the armature; further moving the magnetic unit and the armature in unison to a position wherein the normally open contacts are closed; and fixing the assembly of magnetic unit and armature and contacts in a relationship determined with reference to said position.

26. The method defined in claim 25, wherein there is utilized a shim of insulating material and wherein the magnetic unit is fixed in its adjusted position by welding it to a frame supporting the armature, with said insulating material of the shim preventing any welding attachment of the armature to the magnetic unit.

References Cited UNITED STATES PATENTS 2,605,378 7/ 1952 Carpenter 32428 X 2,633,565 3/1953 Herzog.

2,718,568 9/1955 Somers 335 3,154,653 10/1964 Rowell 335-125 3,164,697 1/ 1965 Bridges 335-125 3,153,711 10/1964 Naybor 200104 3,175,063 3/ 1965 Rhodes 200-104 2,965,954 12/ 1960 Baker 29-155.58 3,057,047 10/1962 Zimmer 29-155.55

JOHN F. CAMPBELL, Primary Examiner.

C. E. HALL, Assistant Examiner.

US. Cl. X.R. 29422

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