US3219785A - Multiple contact stator unit for rotary switch and method of making the same - Google Patents

Description

Nov. 23, 1965 K. c. LlsoN 3,219,785

MULTIPLE T T STA U T FOR ROTARY SWITCH M OD OF MA G THE SAME Filed Feb. l. 1960 3 Sheets-Sheet 1 i; Il|||||||| ZP f MM 2' 0%754 www a M Q EMF f @mwmmn WHWUIZS Il l i MHMHUHHH) Ken-:1572,21 E ZZzsn TTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTT GH O OF KING THE SAME Filed Feb. l. 1960 5 Sheets-Sheet 2 'mm Enz-zei 15cm f Q l NOV. 23, 1965 K. c. ALLlsoN 3,219,785

MULTIPLE CONTACT ST R UNIT FOR ROTARY SWITCH AND MAKI METHOD NG THE SAME Filed Feb. l, 1960 5 Sheets-Sheet 5 mwgw Kem-Leih E'. AZZzsan 35a Erw? United States Patent O 3,219,785 MULTIPLE CONTACT STATOR UNIT FOR ROTARY SWITCH AND METHOD F MAKING THE SAME Kenneth C. Allison, Crystal Lake, Ill., assignor, by mes-ne assignments, to CTS Corporation, Elkhart, Ind., a corporation of Indiana Filed Feb. 1, 1960, Ser. No. 5,686 Claims. (Cl. 200-166) This invention relates broadly to rotary electric switches used extensively in television and radio receivers, and wherein a rotatable contactor is selectively engageable with various stationary contacts arranged in a circle.

More particularly, this invention concerns the stator of such switches and has as its purpose to improve the construction of the stator, and also the method of making it.

The copending application of Kenneth C. Allison, Serial No. 703,980, filed December 19, 1957, now Patent No. 2,988,606, issued on June 13, 1961, illustrates an electric switch of the type to which this invention pertains, and also deals with the manner of producing the stator. As in the invention of that application, the switch stator with which the present invention is concerned, comprises a plurality of Contact fingers fixed to a ring of insulating material by having the medial portions of the fingers embedded in the ring at the time it is molded.

The contact lingers are stamped from a flat blank of sheet metal and are partially defined by successively stamping groups of perforation in an elongated strip of sheet metal, with the perforations of each group so arranged and disposed with respect to one another that the portions of the metal strip between them form circles of substantially radially disposed lingers. The medial portions of these lingers are subsequently embedded in a ring of molded plastic while the lingers are still integrally attached to the strip, and thereafter the projecting portions of the fingers, both inner and outer, are severed from the strip and given their final shape. This is essentially the way in which the stator unit of the aforesaid copending application is produced.

It is perhaps needless to point out that the individual contact lingers must be lirmly anchored in the molded ring of insulating material if the switch is to perform satisfactorily.- Any looseness of any one of the contact lingers would result in unsatisfactory switch performance. While the various eXpedients conventionally employed to anchor inserts in a molding, such as giving the lingers an irregular shape or outline, will `generally result in adequate anchorage, it has been discovered that the plastic material at one side of the circle of fingers, sometimes does not knit properly with the plastic at the other side thereof during the molding operation.

With a view toward overcoming this difiiculty, the present invention has as an important object to provide means by which the plastic material flowing into the mold and around the medial portions of the contact fingers will be deflected from one side of the circle of fingers, through the spaces between them and to the other side thereof, to thus create a mild turbulence in the flowing plastic material which greatly minimizes, if not entirely eliminates the probability of imperfect knitting between the plastic material at opposite sides of the circle of lingers.

More specifically, it is an object of this invention to provide certain or all of the lingers with deflectors which are so disposed and shaped that they provide sloping guide surfaces which extend from one .side of the coplanar lingers to the other side thereof, and thereby cause the liowing plastic material to liow lfrom one side to the other through the spaces between the lingers as the mold lills up. Another important object of this invention is to facilitate the handling of the metal strip during the cleaning there- ICC of preparatory to the molding operation. To this end, the method of this invention includes the formation of spacing means on the perforated strip whereby, after the perforations are formed, the strip may be rolled endwise into a compact roll, but with the adjacent convolutions positively spaced apart so that a long perforated strip can be easily cleaned by immersion in a liquid cleaning solution.

In this connection, it is also an object of this invention to so form the deliectors hereinbefore referred to that they may serve to space adjacent convolutions of the rolled-up strip.

Also in this connectoin, it is still another object of this invention to effect the plating of the exposed portions of the contact fingers while they are still integrally connected to the strip, but with the strip rolled endwise into a compact roll and adjacent convolutions spaced from one another by the molded rings of insulating material.

With the above and other objects in view which will appear as the description proceeds, this invention resides in the novel product and method by which it is made, substantially as hereinafter described and more particularly defined by the appended claims, it being understood that such changes in the precise embodiment of the hereindisclosed invention may be made as come Within the scope of the claims.

The accompanying drawings illustrate one complete example of the physical embodiment of the invention constructed according to the best mode so far devised for the practical application of the principles thereof, and in which:

FIGURE 1 is a plan view of a stator unit made in accordance with this invention;

FIGURE 2 illustrates two stages or steps in the production of the stator unit shown in FIGURE l, and more specifically is a `plan view of a piece of the metal strip from which the contacts of the stator unit are stamped, with the left hand end portion showing the result of the first or initial perforating step, and the right hand end portion showing the insulated carrier ring of the unit in place on the strip;

FIGURE 3 is a side edge view of the piece of strip shown in FIGURE 2;

FIGURE 4 is a plan view of one section of the strip with the molded ring thereon, and illustrating the contacts in their almost completed condition, preparatory to being plated;

FIGURE 5 is a fragmentary sectional view through a portion of the strip to illustrate one of the liow deflectors by which the flow directing feature of the invention is achieved, said view being taken on the plane of the line 5 5, in FIGURE 2, and being drawn at a greatly enlarged scale;

FIGURE 6 is a plan view of that portion of the strip shown in FIGURE 5;

FIGURE 7 is a sectional view through the mold cavity of a plastic press with the perforated strip in place therein and illustrating how the deflectors shown in FIGURES 5 and 6 direct the flow of the plastic material as it lills the mold;

FIGURE 8 is a fragmentary sectional view on the plane of the line 8-8 in FIGURE 7;

FIGURE 9 is a side edge view of the perforated strip rolled lengthwise into a compact roll preparatory to being cleaned; and

FIGURE l0 is a view similar to FIGURE 9, but illustrating the strip rolled up preparatory to the plating step.

Referring now particularly to the accompanying drawings, the finished stator unit shown in FIGURE l comprises a carrier ring 11 molded of suitable insulating material and to which a plurality of contacts 12 are fixed by having portions thereof embedded in the ring.

The ring 11 has perforated, diametrically opposite ears 13 by which the unit may be assembled into a rotary switch. The switch has not been illustrated since the present invention concerns only the stator unit of the switch, and the method of making it. Moreover, reference may be had to the aforesaid copending application Serial No. 703,980, now Patent No. 2,988,606 for a disclosure of the type of switch for which the illustrated stator unit is intended.

The individual contacts 12 are stamped from sheet metal and comprise a circle of separate, angularly spaced lingers 14 disposed substantially radially with respect to the ring 11. They have outer terminal portions or solder lugs 1S and inner contact portions 16 with which one or more rotor contacts (not shown) coact when the stator unit is embodied in a complete rotary switch.

The specific shape and relationship between individual contact portions 16 depends upon the purpose for which the switch is intended. Hence, the structure illustrated in FIGURE 1 is only illustrative. As here shown, certain of the contacts are interconnected by arcuate portions 17 and not all of the contact fingers have terminals, -since only one terminal is needed for each of the arcuate portions 17.

To produce the stator unit of FIGURE 1, in accordance with the present invention, an elongated strip of metal 20 is fed stepwise through a punch press (not shown) which punches a group of perforations 21 into the strip with each operation. These perforations 21 are so arranged and disposed with respect to one another that they define the aforesaid circle of substantially radially disposed fingers 14 which, in subsequent operations, become the contacts 12. Obviously, of course, the punch press has indexing means to index the strip along, and pilot pins which enter pilot holes 23 to properly hold the strip against shifting during the punching operation. The pilot holes 23 are also employed to assure proper registration during molding of the ring 11, and the severance of the embedded contacts from the blank or strip 20.

Except for small projections or protrusions designated generally by the numeral 24, which project from the fingers 14 to one side or the other of the strip, the fingers are coplanar with one another and with the remainder of the strip 20. The projections or protrusions 24 have seevral purposes, but before discussing their function, the structural aspects thereof should be considered.

At the outset, it will be noted that all of the fingers 14 have the projections 24 and that half of the projections extend to one side of the strip or blank 20, while the other half extend in the opposite direction. However, this `specific arrangement can be varied. Also, it is not essential that all of the fingers be equipped with these projections, providing that those fingers which do not have them are equipped with other means, such as non-parallel side edges, to anchor them against endwise displacement, since anchorage of the fingers is one of the functions of the projections 24.

In shape, each individual projection preferably constitutes part of a sphere. Hence, its inner and outer surfaces 25 and 26 respectively, are defined by spherical radii. Each projection has an edge 27 which rises above one side or face of the strip, and from which the wall of the projection slopes or curves back toward the plane of the strip to merge or join therewith.

Accordingly, the inner surface 25 of each projection forms a guide surface extending from one side of the strip to the other side thereof, so that each projection can be considered a deiiector to deflect material flowing toward its edge 27 from one side to the other of the strip.

Since the fingers 14 on which the projections are formed are quite narrow, the projections are at one edge of the fingers, as best shown in FIGURE 6 and, as a result, the edges 27 of the projections are simply continuations of the adjacent side edges 28 of the fingers.

Considering now the purposes or functions of the projections 24, one of these is, of course, the anchorage of the fingers in the molded ring 11, as already stated. Another function of the projections is diagrammatically illustrated in FIGURE 9. As here shown, the strip 20 is rolled lengthwise into a compact roll, but the adjacent convolutions of the roll are positively spaced from one another by the projections 24. Rolling up the `strip in this manner greatly facilitates the necessary cleaning operation in which the strip is prepared for the subsequent molding and plating operations. The cleaning is done by immersing the entire rolled up strip in a bath 0f suitable cleaning solution, and, as should be apparent, by having the convolutions spaced apart as they are by the projections 24, all portions of the strip, though rolled up into a compact roll, will come i-n contact with the cleaning solution.

After the perforated strip has been properly cleaned, it is progressively unrolled and fed, stepwise, through the molding machine or plastic press (not shown) to have a ring 11 molded about the medial portions of each circular group of contact fingers. Any suitable molding machine or plastic press may be used for this purpose; and, likewise, any suitable insulating material which lends itself to being molded in a plastic press may be employed. It is preferable, though, to use a material which contains reinforcing fibers as, for instance, ber glass.

In the molding operation, the molten plastic material is forced under great pressure into the mold cavity, designated generally by the numeral 29 in FIGURES 7 and 8, to completely embed the medial portions of the fingers 14. As shown in FIGURE 7, the material enters the cavity through a gate 30 and flows in opposite directions around the circular cavity at both sides of the strip or group of coplanar fingers 14. As also best seen in FIGURE 7, half of the deflector projections 24 face one way and the others face the other way, but in each case they face toward the gate 30 so as to deiiect the fiowing material from one side to the other of the coplanar fingers. All of the deflectors which face the counterclockwise flow of plastic material, in the arrangement here employed, project upwardly in FIGURE 7; the others project downwardly. Hence, the velocity of the counterclockwise fioW will be faster at the bottom side of the coplanar fingers than at the top side, and for the clockwise ow the velocity of the flow will be faster at the top side. This differential in flow rates results from the deflector action of the projections 24, which impedes the flow at the side of the strip at which the projections lie and tends to increase the flow at the other side.

As a result of the difference in lioW rates at opposite sides of the strip, the junction of the two streams of plastic material will be closer to the gate at one side of the strip or group of coplanar fingers, than at the other side thereof. This has the advantage of strengthening the molded ring by spreading the junction over a greater arc of the circle than would be the case if the material were free to liow in opposite directions at the same rate at both sides of the coplanar fingers. Controlling flow rate is, therefore, another purpose of the projections.

Still another purpose for the projections 24 is to achieve homogeneity for the entire molding. For this to be, the plastic material at one side of the group of fingers must be homogeneously connected to the material at the other side thereof through each of the perforations 21. Before the projections 24 were employed, it was found that this desired homogeneity was not always achieved and that, instead, the material at one side of the group of fingers was imperfectly joined or knit to the material at the other side thereof. The deflection of the flowing plastic through the spaces between adjacent fingers creates a desirable turbulence at each of these points which forces the material at opposite sides of the strip or group of fingers to knit together. It also causes any reinforcing fibers which the material may possess to extend to opposite sides of the plane of the lingers, as shown at F in FIGURE 8. The advantage of this transverse disposition of the fibers is obvious.

All in all, the deilecting action or function of the protrusions 24 greatly improves the resulting molding and materially strengthens it. Incidentally, the arrows in FIGURES 7 and 8 are obviously intended to show the direction of flow of the material in the mold cavity.

After all the groups of fingers 14 have been embedded in molded insulating rings, the strip is again fed through a punch press where the contacts 16 are defined by shearing off the adjacent portions of the strip and in the same way the terminals or solder lugs are more fully dened. In fact, in this punching operation the unit is almost cornpletely defined and remains connected to the strip only at the outer ends of the terminals or solder lugs 15, and the portions of the strip directly adjacent to the diametrically opposite ears 13. Obviously, of course, during this punching operation the pilot holes 23 serve to properly register the strip and hold it in position.

After the just described punching operation, the strip is again rolled up, as shown in FIGURE 10, but this time the adjacent convolutions are held spaced apart by the molded rings 11. In this rolled up condition, the strip is plated, the positive spacing provided by the molded rings being fully adequate to allow the plating solution to reach all portions of the contacts and their terminals.

With the plating done, there remains only the iinal punching operation by which the outer ends of the terminals or solder lugs 15 of the stator unit are severed from the strip or blank.

From the foregoing description taken in connection with the accompanying drawings, it will be readily apparent to those skilled in this art, that this invention greatly facilitates the production of stator units for rotary switches of the type described, and that it results in -a greatly irnproved structure.

It will also be understood by those skilled in the art that while the invention has been illustrated and described as applied to a multiple contact stator unit for rotary switches, it is. equally applicable to multiple contact units of switches of any type, rectilinear as well as rotary; and as to the deflector function of the projections 24, this will be seen to have far broader application than that specifically shown and described, any molding operation in which closely edgewise spaced inserts are involved will be improved thereby.

What is claimed as my invention is:

1. A multiple contact unit for rotary switches having a plurality of individual flat contact blades carried by a body of molded insulating material, to which the contact blades are fixed by having a portion of each of them embedded in the molded body with the contact blades projecting from at least one edge of the body, said unit being characterized: by the fact that all of the at contact blades lie in a lcommon plane intermediate and substantially parallel t-o opposite faces of the molded body; and by the provision of deflectors on the embedded portion of certain of the `contact blades pressed out of the plane thereof, each detlector having an edge which is spaced lfrom t-he adjacent hat side of its respective blade, and from which edge the dellector slopes back toward the plane of the blade to merge with the adjacent flat portion of the blade, certain of the deflectors projecting to one side of the common plane of the inserts while the remainder thereof projecting to the opposite side of said plane 'for anchoring the blade-s provided with the deliect-ors more firmly in the body of molded insulating material disposed `above and below the common plane.

2. A method of manufacturing an electrical component comprising the steps of:

(a) forming a group of perforations in a strip of sheet metal to define a plurality of closely spaced inserts,

(b) deforming parts of the strip adjacent to some of the perforations out of the plane of the strip to form upstanding projections having inclined surfaces leading to the respective perforations,

(c) trolling the strip lengthwise into a compact roll, the adjacent convolutions of the roll being spaced from each other only by the upstanding projections,

(d) cleaning the strip by immersing the compact `roll into a cleaning solution,

(e) removing the strip from the cleaning solution after the lforeign material has been removed from the strip,

(t) unrolling the strip and feeding the unrolled perforated strip into a molding machine,

(g) molding a carrier of insulating material to the ystrip so that the upstanding projections are embedded within the carrier,

(h) `shearing additional portions of the strip of sheet metal to deiine the configuration of the contacts of the electrical component,

(i) rerolling the strip containing the carrier into a compact roll, the adjacent convolutions of the roll being spaced from each other by the carrier,

(j) plating the strip containing the carrier by immersing the compact roll into a plating solution,

(k) removing the strip from the plating solution after a sufficient thickness of plating material has been deposited on the exposed portions of the strip, and

(l) blanking the contacts embedded in the carrier from the strip of sheet metal to produce the electrical component.

3. A method of manufacturing a stator of a multiple contact switch comprising the steps of:

(a) perforating a strip of sheet metal to define a plurality of closely spaced inserts,

(b) molding a carrier of insulating material to the strip to embed at least a portion of each of the closely spaced inserts,

(c) rolling the strip containing the carrier into a compact roll, the adjacent convolutions of the roll being spaced from each other only by tbe carrier,

(d) immersing the strip containing the carrier while in a compact roll into a plating solution .to plate the exposed portions of the strip,

(e) removing the strip from the plating solution after a suflicient thickness of plating material has been deposited on all of the exposed portions of the strip,

(f) unrolling the plated strip, and

(g) blanking the carrier from the strip of sheet metal to produce the stator of a multiple contact switch.

4. A method of manufacturing an article having a plurality of electrical contacts embedded in a carrier of insul ating material comprising the steps of (a) forming a pattern .of perforations in a strip of sheet metal to deiine a plurality of closely spaced inserts,

(b) cleaning the strip to remove foreign material therefrom,

(c) molding a carrier of insulating material to the strip to embed at least a portion of each of the closely spaced inserts,

(d) plating the strip containing the carrier by immersing the strip into a plating solution,

(e) removing the strip from the plating solution after a suiicient thickness of plating material has been deposited on all of the exposed portions of the strip, and

(f) blanking the contacts embedded in the carrier from the strip of sheet metal to produce the article having a plurality of electrical contacts embedded in a carrier of insulating material.

S. A method of manufacturing an article having an electrical terminal embedded in a carrier of insulating material comprising the steps of (a) perforating a strip of sheet metal at spaced intervals,

(b) cleaning the strip to remove foreign material therefrom,

(c) molding a plurality of carriers of insulating material to the strip each of the carriers being at spaced intervals over the perforated portions -of the strip,

(d) rolling the strip containing the carriers into a compact roll, the adjacent convolutions of the roll being spaced from each other only by the carriers,

(e) plating the strip containing .the plurality of carriers by immersing the strip into a plating solution,

(f) removing the strip from the plating solution after a suicient thickness of plating material has been deposited on the exposed portions of the strip, and

(g) blanking successively the carriers from the str-ip to define each of the articles having an electrical 15 terminal embedded therein.

644,574 2,360,063l 2,447,718l 2,631,211 2,670,530 2,713,194- 2,949,511I 2,955,959 3,144,711

References Cited by the Examiner UNITED STATES PATENTS Hayes et al. 134-14 Braddock 134-14 Larson 200166 Simpson 200-11 Klay 200--166 Regnier 29-155.55 Roach a 29-15555 Glueckstein et al 200-11 DuRose 117-113 Stevens 200-11 X ROBERT K. SCHAEFER, Acting Primary Examiner.

MAX L. LEVY, BERNARD A. GILHEANY, Examiners.

Claims (1)

1. A MULTIPLE CONTACT UNIT FOR ROTARY SWITCHES HAVING A PLURALITY OF INDIVIDUAL FLAT CONTACT BLADES CARRIED BY A BODY OF MOLDED INSULATING MATERIAL, TO WHICH THE CONTACT BLADES ARE FIXED BY HAVING A PORTION OF EACH OF THEM EMBEDDED IN THE MOLDED BODY WITH THE CONTACT BLADES PROJECTING FROM AT LEAST ONE EDGE OF THE BODY, SAID UNIT BEING CHARACTERIZED: BY THE FACT THAT ALL OF THE FLAT CONTACT BLADES LIE IN A COMMON PLANE INTERMEDIATE AND SUBSTANTIALLY PARALLEL TO OPPOSITE FACES OF THE MOLDED BODY; AND BY THE PROVISION OF DEFLECTORS ON THE EMBEDDED PORTION OF CERTAIN OF THE CONTACT BLADES PRESSED OUT OF THE PLANE THEREOF, EACH DEFLECTOR HAVING AN EDGE WHICH IS SPACED FROM THE ADJACENT FLAT SIDE OF ITS RESPECTIVE BLADE, AND FROM WHICH EDGE THE DEFLECTOR SLOPES BACK TOWARD THE PLANE OF THE BLADE TO MERGE WITH THE ADJACENT FLAT PORTION OF THE BLADES, CERTAIN OF THE DEFLECTORS PROJECTING TO ONE SIDE OF THE COMMON PLANE OF THE INSERTS WHILE THE REMAINDER THEREOF PROJECTING TO THE OPPOSITE SIDE OF SAID PLANE FOR ANCHORING THE BLADES PROVIDED WITH THE DEFLECTORS MORE FIRMLY IN THE BODY OF MOLDED INSULATING MATERIAL DISPOSED ABOVE AND BELOW THE COMMON PLANE.

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