US3442004A - Method of making electrical switches - Google Patents

Description

May 6, 1969 w. N. SCHINK METHOD OF MAKING ELECTRICAL SWITCHES Original Filed July 2, 1964 Sheet FIG. J.

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METHOD OF MAKING ELECTRICAL SWITCHES Original Filed July 2, 1964 Sheet 2 of 2 I/v VEN Tog Wiilzam N Saki/2k 7/4 I M aM aizfys United States Patent 3,442,004 METHOD OF MAKING ELECTRICAL SWITCHES William N. Schink, Crystal Lake, Ill., assignor to Indak Manufacturing 'Corp., Northbrook, IlL, a corporation of Illinois Original application July 2, 1964, Ser. No. 379,894, now Patent No. 3,329,790, dated July 4, 1967. Divided and this application Feb. 9, 1967, Ser. No. 614,999

Int. 'Cl. H01h 65/00 US. Cl. 29-622 3 Claims ABSTRACT OF THE DISCLOSURE This application is a division of my copending application, Ser. No. 379,894, filed July 2, 1964 and now United States Patent 3,329,790.

This invention relates generally to electrical switches or the like and pertains particularly to a method of making such switches.

The Soreng Patent No. 2,868,906, patented Jan. 13, 1959, discloses an electrical switch having fixed contacts in the form of thin plate-like members mounted on the front face of an insulating plate or board. The plate-like contact members have previously been formed by circuit printing techniques. However, it has been found that such printed circuit contact members are lacking in durability and are prone to wear out after a relatively short period of use. Such printed circuit contact members are subject to damage due to electrical arcing, as well as ordinary abrasion.

The general object of the present invention is to provide a method whereby such printed circuit contact members may be eliminated, in favor of contact members made of sheet metal or the like, while avoiding any difficult assembly operations, and while holding the cost of the switch to an absolute minimum.

Thus, one particular object of the invention is to provide a new and improved method involving the initial step of forming a plurality of contact segments as a single piece or unit, stamped from sheet metal, and with an interconnecting outer spider. The unit is then mounted on an insulating board having semi-perforated projections which extend between the contact segments. A Single rivet or other fastener is employed to secure each contact segment to the board. The outer spider is then trimmed away or otherwise removed. The semi-perforated projections prevent rotation of the contact segments about the rivets.

Another object is to provide a new and improved method whereby the insulating plate or board is formed with a recess, adapted to receive a prong or key on a terminal or the like, by squeezing the recess part way into one side of the insulating board, preferably adjacent an opening therein.

Further objects and advantages of the present invention ice will appear from the following description, taken with the accompanying drawings, in which:

FIG. 1 is a side elevational view of an electrical switch to be described as an illustrative embodiment of the pres ent invention.

FIG. 2 is a rear elevational view of the switch.

FIG. 3 is a front elevational view.

FIG. 4 is an enlarged longitudinal section through the switch, taken generally along the line 4-4 in FIG. 5.

FIG. 5 is a cross-sectional view taken generally along the line 5-5 in FIG. 4.

FIG. 6 is a front view of the insulating board employed to support the contact segments and terminals in the switch of FIGS. 1-5.

FIG. 7 is a front elevational view of a one piece metal stamping which is mounted on the insulating board to provide all of the contact segments, after which the outer spider portion of the stamping is trimmed away.

FIG. 8 is a fragmentary enlarged somewhat diagrammatic sectional view taken generally along the line 8-8 in FIG. 6.

FIG. 9 is an elevational view of a different construction, forming another illustrative embodiment of the present invention.

FIG. 10 is a fragmentary enlarged section taken generally along the line 10-10 in FIG. 9.

FIG. 11 is a fragmentary section taken generally along the arcuate line 11-11 in FIG. 9.

The contact and terminal construction of the present invention will be described as embodied in a rotary electrical switch 20, shown generally in FIGS. 1-3. The switch is of the general type disclosed and claimed in the Soreng Patent, No. 2,868,906, patented Jan. 13, 1959, and assigned to the same assignee as the present application. It will be seen that the switch 20 comprises a rotary operating shaft 22 to which a knob 24 is secured. The switch may also be arranged for key operation, if desired. The shaft 22 is rotatably mounted in a bearing sleeve or bushing 26 which extends forwardly from the front wall 28 of a generally cylindrical cup-shaped casing or housing 30. The switch 20 is adapted for mounting on a panel 32 having an opening 34 therein for receiving the bushing 26. Screw threads 36 are formed on the bushing 26 to receive a nut 38 for securing the switch to the panel 32. Within the casing 30, the switch has an insulating rotor 40 which may be made of various plastics or other suitable insulating material. The rotor 40 has a hub 42 which is suitably connected to the shaft 22 and is rotatable therewith.

In this case, the rotor 40 carries two diametrically opposite contactors 44, but the contactor arrangement may be varied to accomplish various switching functions. Each of the illustrated contactors 44 comprises a metal plate 46 which faces rearwardly and is in a radial plane perpendicular to the axis of the rotor 40. An inner contact point 47 and two outer contact points 48 and 49 project rearwardly from the plate 46. The contact points 47-49 are generally hemispherical in shape. It will be seen that the contact points 4749 are arranged in a triangle, and that the plate 46 is generally triangular in shape.

Each contactor 44 has a pair of prongs 50 and 51 which project into guide slots or openings 52 and 53 formed in the rear side of the rotor 44. Thus, the contactors 44 are guided for movement from front to rear. A spring 54 is compressed between the rotor 40 and each contactor 44 and is effective to bias the contactor rearwardly, away from the rotor. Each spring 54 is re- 3 ceived in a socket or slot 56 formed in the rear of the rotor 40.

In the illustrated switch, the contactors 44 are engageable with an inner or central contact segment 60 and five outer contact segments 61-65 which are mounted to the rear of the rotor 40 and in a radial plane perpendicular to the axis thereof. The central segment 60 and the outer segment 61 are connected together and may be formed in one piece, but the other segments 62-65 are insulated from each other and from the segments 60 and 61. The outer segments 61-65 are arranged in a circle around the central segment 60. It will be seen that the inner contact points 47 on the contactors 44 are engageable with the central segment 60, while the outer contact points 48 and 49 are engageable with the outer contact segments 61-65. The contactors 44 are adapted to act as bridges to complete various electrical circuits between the central segment 60 and the outer segments 61-65.

The segments 60-65 are in the form of metal plates mounted on an insulating terminal board or plate 68 which is circular in shape and closes the rear side of the casing 30. In this case, the insulating board 68 is secured to the casing 30 by a flange portion 70 thereon which is turned inwardly behind the insulating board.

The insulating board 68 may be made of a suitable insulating material, such as a phenolic plastic, for example, preferably having a surface coating 72 made of a heat-resistant material such as melamine plastic.

The illustrated contact segments 61-65 are secured to the insulating board 68 by suitable fasteners which may take the form of rivets 81-85. Holes 86-90 are formed in the insulating board 68 to receive the rivets 81-85. The central contact segment 60 is part of the segment 61 and is secured to the insulating board 68 by the rivet 81.

The rear ends of the rivets 81-85 project behind the insulating board 68 and are employed to secure terminal lugs 91-95 to the rear side of the insulating board. In this case, a resistor 96 is connected between the terminal lugs 93 and 95, which are somewhat longer than the others. The resistor 96 is in the form of a coil of resistance wire. The terminal 91 may be connected to the battery or other source of power, while the other terminals 92-95 may be connected to lighting circuits or the like which are adapted to be controlled by the switch. The illustrated switch is intended particularly for controlling the lights on an automotive vehicle, but may be used for various other applications.

Each of the illustrated terminal lugs 91-95 is bent into an L-shape to form a base portion 98 and a rearwardly projecting leg 100. In each case, the base portion 98 is clamped against the rear of the terminal board 68 by the corresponding rivet. Thus, a rivet hole 101 is formed in each base portion 98. Means may be provided to connect leads to the rearwardly projecting legs 100. Thus, some or all of the legs 100 may be fitted with terminal screws 102.

To prevent the terminal lugs 91-95 from turning about the rivets 81-85, the base portion 98 of each terminal lug is formed with a prong 104 which projects forwardly adjacent the rivet hole 101. Some of the rivet holes in the insulating board 68 are formed with key ways or slots 106 to receive the prongs 104. Thus, such key ways 106 connect with the outer side portions of the rivet holes 86, 88 and 90, as shown in FIG. 6. In the case of each of the remaining rivet holes 87 and 89, a recess 108 is formed in the rear side of the insulating board 68 adjacent the outer side portion of the rivet hole. The recess 108 extends only part way through the insulating board 68. Each recess 108 may be formed by a die operation in which the recess is squeezed into the insulating board 68 by a die which applies high pressure to the area in which the recess is to be formed.

In this case, the central contact segment 60 is formed with an axial eyelet or bushing 110 which provides a rear bearing for the rotor 40. The eyelet is cylindrical in shape and is formed integrally with the central contact segment 60. It will be seen that the eyelet 110 projects forwardly into a socket or bore 112 formed in the rear side of the rotor 40. The front of the rotor 40 is supported by the shaft 22 which has a portion 114 rotatably supported in a bore 116 which is formed in the bushing 26.

The contact segments 60-65 are preferably made of brass, copper or other sheet metal which is highly cOnductive and which is easy to stamp and form, so that the various segments and the eyelet portion 110' may easily be formed. I

In accordance with one of the important features of the present invention, the insulating board 68 is formed with a plurality of semi-perforated segments or members 121-126 which project forwardly from the insulating board and are disposed in the spaces or openings between the various contact segments. The semi-perforated members 121-126 serve the function of positively locating the contact segments 60-65 so as to prevent them from rotating about the rivets 81-85. In addition, the semiperforated members provide smooth surfaces which are flush with the front surfaces of the contact segments 60- 65, to provide for smooth contact movement between the contact segments. The semi-perforated members 121-126 are preferably punched forwardly from the insulating board 68 by a. die-forming operation. The forward displacement of the semi-perforated members is clearly shown in FIG. 8.

The semi-perforated segments or bosses 121-125 are arranged around the circular path which is traversed by the outer contact points 48 and 49 of the contactors 44. Thus, the outer contact points 48 and 49 ride along the semi-perforated segments 121-125 when the contact points pass between the various contact segments 61-65. It will be seen that the semi-perforated segment 121 extends between the contact segments 61 and 62. The semiperforated segment 122 extends between the contact segments 62 and 63. The semi-perforated segment 123 extends between the contact segments 63 and 64. Similarly, the semi-perforated segment 124 extends between the contact segments 64 and 65 while the semi-perforated segment 125 extends between the contact segments 65 and 61.

The remaining semi-perforated segment 126 is along the smaller circle traversed by the inner contact points 27 of the contactors 44. It will be seen that the semiperforated segment 126 is disposed in a notch or cutout 128 formed in the central contact segment 60.

Each of the semi-perforated segments 121-126 has a smooth front surface 130 which is substantially flush with the front surfaces of the contact segments '60-65. A recess 132 in the rear side of the insulating board 68 results from the formation of each of the semi-perforated segments 121-12-6.

In accordance with the present invention, it is preferred to employ a method of manufacture in which all of the contact segments 60-65 are formed initially in a single piece or blank 134 which is stamped from sheet metal. In addition to the various contact segments 60-65, the blank 134 incorporates an outer spider portion 136 which comprises a circular ring 138 extending around the outside of the blank. The spider 136 also comprises a plurality of radial arms 141-149 which extend between the ring 138 and the various contact segments 61-65. It will be seen from FIG. 7 that each of the contact segments 61-65 is supported by two of the arms 141-149, except that the contact segment 64 is supported only by the arm 147, which is wider than most of the other arms.

The contact assembly is produced by mounting the one-piece blank 134 on the front side of the insulating board 68. The semi-perforated segments 121-126 result in the precise positioning and orientation of the blank 134 relative to the insulating board. The blank 134 is secured to the board 68 by inserting and setting the rivets 81-85. Finally, the spider portion 136 of the blank 134 is removed by a trimming operation which severs all of the radial arms 141-149 along a circular trim line 150.

This method of manufacture is easy and extremely economical. Nevertheless, the various contact segments 60-65 are positioned with a high degree of precision. The semi-perforated segments 121-126 prevent any movement of the contact segments 60-65 about the rivets 81-85.

In summary, the semi-perforated segments or bosses 121-126 play an important role in the manufacture of the contact assembly, in that the one-piece metal 'blank 134 is precisely located and oriented by the semi-perforated segments. After the rivets 81-85 have been set and the spider portion 136 of the blank 134 has been trimmed away along the line 150, the semi-perforated segments 121-126 maintain the precise positioning of the contact segments 60-65 and prevent any rotation of the segments about the rivets 81-85. Due to the provision of the semi-perforated segments, only one rivet is needed for each of the sheet metal contact segments.

The semi-perforated segments 121-126 also form slide surfaces 130 which are flush with the front surfaces of the contact segments 60-65 so as to provide for smooth contact movement between the contact segments. The semi-perforated segments 121-126 virtually eliminate any roughness or any false detenting action in the operation of the switch.

The semi-perforated segments 121-125 are disposed between the contact segments 61-65 and are effective to minimize the electrical arcing between the contactors 44 and the contact segments. The semi-perforated segments tend to cool and extinguish the arcs which form when the various circuits are broken by the movement of the contactors. The melamine plastic coating on the semiperforated segments is especially resistant to the heat generated by the electrical arcs.

FIGS. 9-11 show the manner in which the present invention may be applied to a quite different contact construction 160, comprising an arcuately-shaped insulating board 162 which supports a one-piece contact plate 164. It will be seen that the contact plate 164 comprises three contact segments 166, 167 and 168, all of which are connected together electrically by continuous inner and outer border portions 170 and 172 on the plate 164. Segmental openings 174 and 175 are formed in the plate 164 to define the spaces between the segments 166-168.

In accordance with the present invention, semi-perforated segments 178 and 179 are punched forwardly from the insulating board 162, that is, sheared and offset therefrom, for reception in the openings 174 and 175. The semi-perforated segments 178 and 179 correspond in size and shape to the openings 174 and 175 and serve to locate the contact plate 174 with a high degree of precision on the insulating board 162. The semi-perforated segments 178 and 179 are preferably punched forwardly from the insulating board 162 by a die-forming operation. It will be seen that the front surfaces of the semi-perforated segments 178 and 179 are flush with the front surfaces of the contact segments 166-168, so as to provide for smooth contact movement between the contact segments.

Suitable means are provided to secure the contact plate 164 to the insulating board 162. As shown, this is accomplished by two pairs of inner and outer tabs 181 and 182 which project rearwardly from the metal plate 164 and are bent over behind the insulating board 162. The inner tabs 181 project through slots or openings 183 in the insulating board 162. Notches 184 are formed in the board 162 to receive the outer tabs 182.

An inclined semi-perforated segment 186 is formed from the insulating board 162 adjacent the contact segment 166 to provide a ramp, whereby contacts may be moved in a smooth manner onto and off the contact segment 166. The semi-perforated segment 186 slants from a level flush with the contact segment 166 to the level of the front surface of the board 162, as shown to best advantage in FIG. 11. 5 Thus, the present invention is applicable to a wide variety of contact constructions, in which it is desired to achieve precise and positive location of sheet metal contact members on an insulating plate or board. The present invention has the added advantage of providing smooth contact movement between the contact segments. Various other modifications, alternative constructions and equivalents may be employed without departing from the true spirit and scope of the invention, as exemplified in the foregoing description and defined in the following claims.

I claim: 1. A method of making a contact assembly for switches or the like,

said method comprising: stamping a unit from sheet metal and comprising a plurality of contact segments and an interconnecting spider having an outer substantially circular ring portion extending around said segments and a plurality of radial portions extending between said segments and said ring portion, said segments having spaces therebetween, forming a substantially circular insulating board having at least one contact mounting surface interrupted with a plurality of segmental semi-perforated members projecting therefrom by shearing and offsetting portions of said board to correspond to certain of the spaces between said contact segments, mounting said contact unit against said insulating board with said semi-perforated members projecting into said spaces and the sheared edges of said members engaging and locating said contact unit on said insulating board, riveting said contact segments to said insulating board with a single rivet for each contact segment, and trimming away said interconnecting spider from said contact unit while leaving said contact segments on said insulating board. 2. A method of making a contact assembly for switches or the like,

said method comprising: stamping a blank from sheet metal and comprising a plurality of contact plates and an interconnecting spider, said plates having spaces therebetween, forming an insulating board having at least one contact mounting surface interrupted with a plurality of semi-perforated members projecting therefrom by shearing and offsetting portions of said board to correspond to certain of the spaces between said contact plates, mounting said blank against said insulating board with said semi-perforated members projecting into said spaces and the sheared edges of said members engaging and locating said blank on said board, securing said contact plates to said board, and removing said interconnecting spider from said blank while leaving said contact plates on said insulating board. 3. A method of making a contact assembly for switches or the like,

said method comprising forming a blank from sheet 65 metal and comprising a plurality of segmental contact plates and a generally circular interconnecting spider extending between said contact plates, said contact plates having spaces therebetween, forming an insulating board having at least one contact mounting surface interrupted with a plurality of segmental semi-perforated members projecting therefrom by shearing and offsetting portions of said board to correspond to certain of the spaces 'between said contact plates, mounting said blank against said board with said semiperforated members projecting into said spaces and the sheared edges of said members engaging and locating said blank on said board,

fastening said contact plates to said board,

and removing said interconnecting spider While leaving said contact plates on said board.

References Cited UNITED STATES PATENTS 8 3,146,315 8/1964 Hazelquist 29630 XR 3,214,536 10/1965 Wallace 29630 XR 3,248,488 4/1965 Stephan 29-630 XR FOREIGN PATENTS 993,984 6/ 1965 Great Britain.

JOHN F. CAMPBELL, Primary Examiner.

R. W. CHURCH, Assistant Examiner.

U.S. Cl. X.R.

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