US2531911A - Shield can with spring attachment means - Google Patents

Description

@@ ge/A fig. 9

l INVENTOR Edufdfd 7015175011 BY C Z l W KTM Filed Dec. 15, 1945 fig. 7

E L JOHNSON SHIELD CAN wITH SPRING ATTACHMENT MEANS i wila Nov. 28, 1950 Patented Nov. Z8, 1950 SHIELD CAN WITH SPRING ATTACHMENT MEANS Edward L. Johnson, South Orange, N. J., assignor to The Palnut Company, Irvington, N. J., a corporation of New Jersey Application December 15, 1945, Serial No. 635,392

8 Claims.

This invention is particularly applicable to the attachment of an electrostatic shielding can to a chassis plate and hence it will be disclosed and discussed in that connection. Certain features of the invention are, however, applicable to other attachments.

Coils and other circuit'elements employed in radio and other electrical apparatus are cus. tomarily mounted upon a metal chassis plate. Often these elements require shielding, usually electrostatic shielding. A common form of electrostatic shield is a metal can (usually aluminum) which is telescoped over the coil or other circuit element and secured to the chassis plate. Sometimes these ,cans are merely tubular bodies but ordinarily one end of the tube is closed and the other end is open, the open end or mouth being placedagainst or adjacent .to the chassis plate. For quantity production and assembly of apparatus of this sort, some inexpensive means is necessary for quickly and reliably securing the shielding can to the chassis plate. Also, the securing means should be one which provides for ready removal of the can for replacement of, or servicing of, the circuit element enclosed within it. Various devices have been used or suggested for attaching shielding cans to chassis plates, but none of them known to me has had as great facility of assembly or as great reliability in use as is desirable. Also various of theattachment means used heretofore have been more expensive to manufacture than is desirable.

An object ofthe present invention is to provide an inexpensive shielding-can and chassisplate assembly wherein the can can be secured to the chassis plate with great rapidityand with a high degree of l reliability in the resulting attachment.

Another object of the invention is to provide an improved shielding-can and chassis-plate attachment requiring only a simple telescopic motion to effect the assembly.

A further object of the invention is to provide a fastening device for attaching a shielding can to a chassis plate, of such character that the attachment can be made by a simple telescoping movement and that thereafter the can will be held against the chassis plate by spring tension.

Additional objects of the invention are to provide a fastening device which can he rapidly and inexpensively y manufactured from sheet metal, which attaches the parts of the assembly by simple telescopic movement, which provides for expeditious disassembly, and which requires neither tools nor any skilled operation to mak the assemblyandthe disassembly. l .Y f

My invention'is Yclearly defined in tl'zeappend.-l ed claims. Where parts-fare, for clarity and convenience, referred tol on the basis of their oriented-r` ostionv shown in the accompanying drawing, no limitation as to positioning of the entire structure is to be implied, since it will be understood that the entire structure may be inverted or that it may be used in any inclined position. Also in both the description and ythe claims, parts at times may be identified byspecic names for clarity and convenience, but such nomenclature is to be understood as having the broadest meaning consistent with the context and with the concept of my invention as distinguished from the pertinent prior art. The best form in which I have contemplated applying my invention is illustrate-:l in the accompanying drawing forming part of this speciiication, in which:

Fig. l shows a shielding-can and chassisplate assembly embodying the present invention, the can being shown in side elevation and the plate being shown in section.

Fig. 2 is a View similar to Fig. l, the assembly being viewed at right angles to the direction. of

view of Fig. l, and the view illustrating the manner in which the can is installed on the plate. This view shows the can in elevation and the plate in section, the line of section of the plate being midway between the right and left sides of the can as viewed in Fig. l.

Fig. 3 is a horizontal section taken on the lines 3-3 of Fig. 1.

In Figs. l, 2 and 3, a first form of the fastening device is shown.

Fig. 4. is a front elevation, on an enlarged scale, showing a second form of fastening device per se.

Fig. 5 is a side elevation of the second form of fastening device per se, drawn to the same scale as Fig. 4.

. Fig. 6 is a detail View on a still larger scale, partly in elevation and partly in section, showing the latching of either the rst or second forms of fastening device to the chassis plate.

.Fig '7 is a view similar to Fig. 6 showing a modification which may be incorporated in both the first and second forms of fastening device.

Fig. 8 is a detail sectional view showing a fas. tener-receiving hole in a chassis plate and a burr associated with the hole. y

Fig. 9 is a detail sectional view'showing a fastener-receiving hole in a chassis plate and fastener-interlocking indentations which may `optionally be formed adjacent thereto.

A shielding can designated as a whole by I0 has a tubular body ll, and it may have atop I2. The can is adapted to enclose a coil or other circuit element indicated diagrammatically aty I3 and which may be attached to eitherthe chassis plate or the can. Ordinarily the bottom of the secured to oppositesides of the can-bodyll are 3 fastening devices I5, I5. 'I'hese have end portions which project through rectangular holes I6, I in the chassis plate and latch beneath the plate, each hole I6 and the surrounding metal constituting a receptacle to receive the end portion of the fastening device.

Each fastening device I is a one-piece sheet metal stamping having a hub lI provided with a hole analogous to hole 24 in Fig. 4. Extending upwardly and then laterally from the hub is an L-shaped finger I8. Extending downwardly from the hub are spaced legs i9 and 2i! disposed in edge-to-edge relation. The end portion b of each leg is so formed as to p rovide a cam surface c and a latching lip d. The legs I9 and 26 are bowed laterally throughout a zone Z, the arc of the bowed portion being preferably substantially less than a semicircumference, as is shown in the drawing. The fastener is made of suitable springy metal, and I preferably stamp it from sheet metal. For most purposes I prefer to stamp it from spring steel and then harden and temper the stamping. Phosphor bronze, beryllium copper, spring brass, and other spring alloys may also be used.

The fastener I5 may be fixedly secured to the can I9 by a rivet 25 which passes through a hole therein and a suitably located hole in the side wall of the can. 'I'he can is provided with a suitable formation, e. g., a hole 26, which nger I8 engages to prevent thefastener from swinging pivotally on rivet 26; The can-,adjacent surface of the hub I1 lies directly against the can and establishes the attachment plane of the fastener.

Prior to assembly of the can with the plate, the circuit element I3 is mounted either on the plate or inthe can. Then the can is put in place,

4 plane of the underside of the chassis plate. This is shown in Fig. 6. It is not desirable that these lips extend outwardly and downwardly from the legs, as the lips would then tend to cam out of holes I6, I6 under the spring action of the bowed portion Z of the fasteners. I prefer that the lips d, d be so disposed as to nominally extend outwardly and somewhat upwardly from the legs, so that under the variations incident to quantity production there will be no danger of the lips of any particular fastener extending outwardly and downwardly.

Fig. '7 shows fastener legs I9a and 26a provided with latching lips d", d extending outwardly upwardly to such an Leinem; as to give definite prongs p,- p which will embed somewhat in the metal of the plate I4, particularly if it be of aluminum or other soft metal. When so embedded these prongs oppose any Vaccidental or fortuitous movement of the legs iSd and 28a toward unlatching position. Also, the chassis plate may be a plate Ifla (Fig. 9) provided with a rectangular hole ISa adjacent to which are preformed indentations such as e, e to receive the tips of outwardly-upwardly inclined latching lips. Alternatively, the chassis plate may be a plate leb (Fig. 8) having a fastener-receiving hole |612 so stamped as to leave a burr 3| on the underside Y which will oppose accidental unlatching of the the ends of the fasteners I5, I5 being inserted into the rectangular holes I 6, I 6, the spacing of which is equal to the spacing between the end portions of the two fastening elements i5. I5 which are attached to the can. The long dimension of each hole I6 is such that as the end of the fastener enters the hole, the short edges of the hole are engaged by the cam surfaces c, c, thereby forcing legs I9 and 29 toward one another. The proportionof parts is such that without distortion of the bowed portion Z of legs I9 and 2G, the lips d will not pass beneath the chassis plate. -owever, vby exerting inward pressure on the bowed portions of the two fasteners with the thumb and forefnger, as indicated in Fig. 2, the bowed portions will be flexed, resulting in elongation of the fasteners and such extension of the ends of the y fasteners that the lips d, d will pass beneath the chassis plate. Thereupon the legs I9 and 20 will spread due to their resiliency, and the fasfastener by forming a barrier to accidental unlatching' movement of the tips of outwardly-upwardly inclined latching lips.y

Itwill be seen that by means of two fasteners I5, I 5 a shielding can may be quickly and securely installed on a chassis plate. Any force tending toshift the can laterally on the plate, as viewed in Fig. 2, is promptly opposed by the bottom portion of the can laterally engaging one of the fasteners I5 which is held against latral movement by its telescopic arrangement with plate hole I6. f the can bershifted laterally as viewed in Fig; l, it may tend to shift the end of either fastener leg I9 or fastener leg 20 to a position of lesser latching engagement with the plate, but the other leg of the fastener either cannot move or is pushed further into latching relation with the plata For some classes of service, interfitting orinterlocking formations are provided between the can and the plate to tener will latch to the chassis plate as shown in Figs. 1 and 6. In such latched condition the bowed legs I9 and 20 are maintained under stress and hold the end of the can against the chassis plate by spring tension. This is of great advantage, not only to prevent looseness and rattling of the can, but also to establish and maintain low resistance electrical connection of the can to the chassisplate. i

To remove thecan I0, the end portions b, b of each fastener are manually pressed toward one 'firiotlieny whereupon the springybowed portion ofgach fastener Vretracts tlieiips d. d into hole i6, the can may then be lifted from the chassis p a e. Y I Y The lips d, d may beso disposed that when latched to the chassis plate these lips lie. inthe.

'lli

oppose lateral and rotative forces tending to shift the can on the surface of the plate. Fig. 3 shows the plate I4 provided with a plurality of upstruck tabs 28 that are arranged in a series which is embraced by the open end of the can. These tabs and the open end portion of the can constitute intertting formations effective to oppose rotative and lateral movement of the can on the surface of the plate. It will be understood, however, that for many classes of service these tabs 28 may be omitted, no interntting between the can per se and the plate being needed.

Fig. 2 shows the open end or mouth of the canl provided with a projecting tongue 29, one or more of which may be provided on opposite sides of the can to interlock with appropriately located additional holes such as 30 in the chassis plate to oppose rotative and lateral movement of the can on the surface of the plate. Only a single tongue 29 is shown in Fig. 2 and it is located at the back side of the can as viewedin Fig. 2. Since the line of section of plate I4 in Fig. 2 is midway between the front and back sidesof the canas viewed in that ngure, the tongue 29 and the hole 3U appear only inl dotted lines. vIt will b9 understood that tongues V29 may be either in addition to, or in lieu of tabs 28, and that for many classes of service both may be omitted.

The can l2,` instead of being equipped with the first form of fastener shown in Figs. 1, 2 and 3, may be equipped with fasteners of the second form which is shown in Figs. 4 and 5. When so equipped, the can may be latched to and unlatched from the chassis plate in the same manner. However, the form of fastener shown in Figs. 4 and 5 affords a more positive and secure attachment of the can to the chassis plate as will presently appear.

The second form of fastener, designated as a whole by I5', differs from the first form of` fastener primarily in its different proportioning and in the addition of a bridge member connecting the two legs of the fastener. Fastener I5 includes a hub l1', an L-shaped finger I8', a bowed portion Z', end portions b', b', cam surfaces c', c and latchingA lips d', d; all of these parts corresponding tothe parts of fastener l5 which are designated by reference characters which correspond respectively but which do not have a prime mark. When a can such as i2 is to be equipped with vthe second form of fastener, it will, of course, be provided with suitably located attachment vholes positioned to register with hole 24 and finger I8.

The legs I9 and 20 are connected by an integral bridge 4Q which is preferably located near the middle of the legs. When the ends b', b' of the legs are cammed towards one another, the bridge is fiexes, the fieXure disappearing as the ends b', b move into latched relation with the chassis plate. The bridge stiffens the fastener in respect to the edgewise movement of the free ends of the legs toward and away from one another in latching and unlatching, without however stiffening the legs in respect to the thumb and finger pressure required to distort the bowed portion Z in making an assembly as indicated in Fig. 2.

The end portions of the legs of fastener l5 may be formed either as shown in Fig. 6 or Fig. 7. If formed as shown in Fig. 6 the latching lips will lie in the plane of the underside of the chassis plate. If formed as in Fig. '7 the latching lips will incline outwardly-upwardly from the legs giving the definite barb-like prongs, p, p shown in Fig. "1. The second form of fastener l5' may, of course, be used with the chassis plate Ia of Fig. 9 or with the chassis plate Mb of Fig. 8, both of which have already been described.

Bridge 4i! is preferably located far enough from hub ll to provide an opening 4l which is long enough to permit another fastener to drop readily through the opening. This prevents one fastener from becoming latched to another when a number of fasteners are bullied together for handling or shipping. In some instances the two legs of the fastener may be connected by two integral bridges which are spaced apart lengthwise of the fastener legs. In such case the opening between the hub and the nearest bridge, and the opening between the two bridges, may be made so small that it is impossible for the end of another fastener to latch into these openings.

claim:

1. In a shield-can and chassis-plate organization, a shield can, a chassis plate, a pair of elongated fasteners attached to opposite sides of the can, the fasteners extending beyond the mouth of the can and being provided with terminal latching formations to project through holes in the chassis plate and latch thereto, said terminal formations being initially too close to the mouth of the can to latch to the plate, and the fasteners having springy portions which are bowed outwardly from the sides of the can, said outwardly bowed portions being deformable toward the can by thumb and linger pressure to thereby extend the terminal formations to a sufficient distance from the mouth of the can to latch to the plate, and said outwardly bowed portions, upon completion of the assembly, exerting spring pressures which biases the mouth of the can against the plate.

2. In a shield-can and chassis-plate organization, a shield can, a chassis plate, a pair of elongated fasteners of springy sheet metal attached to opposite sides of the can, the fasteners extending beyond the mouth of the can and being provided with terminal latching formations to project through holes in the chassis plate and latch thereto, said terminal formations being initially too close tothe mouth of can to latch to the plate, and the fasteners having springy portions which are bowed outwardly from the sides ofthe can, said outwardly bowed portions being deformable toward the can by thumb and nger pressure to thereby extend the terminal formations to a sufficient distance from the mouth of the can to latch to the plate, and said outwardly bowed portions, upon completion of the assembly, exerting spring pressure which biases the mouth of the can against the plate.

3. A springy snap-in fastener of stamped sheet metal comprising a hub and a pair of spaced legs eznending therefrom in edge-to-edge relationship, the hub and the end portions of the legs lying in the pl ane of the sheet and the major intervening portions of the legs being bowed transversely of the plane of the sheet and rendering the legs yieldingly extensible by lateral pressure applied to the bowed portions, the hub being pierced for to a member that is to be fastened. the end portion of each leg being provided with a cam surface for camming the leg toward the other leg when theends of the legs are inserted into a suitable hole in a plate-like support, and the end portion of each leg being also provided with an outwardly extending lip for latching with the plate-like support.

4.'. A springy snap-in fastener of stamped sheet metal comprising a hub and a pair of spaced legs extending therefrom in edge-to-edge relationship, the hub and the end portions of the legs lying in the plane of the sheet and the major intervening portions of the legs being bowed transversely of the plane of the sheet and rendering the legs yieldingly extensible by lateral pressure applied to the bowed portions, the hub being pierced for riveting to a member that is to be fastened and being provided with a projecting finger to interlock with the member and prevent rotation of the fastener on the rivet, the end portion of each leg being provided with a cam surface for camming the leg toward the other leg when the ends of the legs are inserted into a suitable hole in a plate-like support, and the end portion of each leg being also provided with an outwardly extending lip for latching with the plate-like support.

5. A fastener composed of a single piece of stamped spring sheet steel, hardened and tempered, said fastener comprising: a pierced hub for attachment by a rivet to a member to be fastened, the hub establishing an attachment plane at which the fastener engages the member to be fastened, a finger adjacent the hub and p: i, projecting inwardly from the attachment .plane for engagement with a formation in the member to hold the fastener against rotation about the rivet, a pair of elongated spaced legs extending from the hub in edge-to-edge relationship, latching formations on the ends of the legs for telescopic latching with a complementary member, and a nXedly-positioned bridge connecting the legs at a location remote from both ends of both legs, a longitudinal zone of each leg being formed as a spring portion bowed outwardly of the attachment plane, the bowed spring portion being deformable by nger pressure to lengthen the leg and being operative when released to resiliently retract the end of the leg.

6. A fastener composed of a single piece of stamped spring sheet steel, hardened and tempered, said fastener comprising: a hub portion for attachment to a member to be fastened, the hub establishing an attachment plane at which the fastener engages the member to be fastened, a pair of elongated spaced legs extending from the hub in edge-to-edge relationship, latching formations on the ends of the legs for telescopic latching with a complementary member, and a iiiedly-positioned bridge connecting the legs at a location remote from both ends of both legs, a longitudinal zone of each leg being formed as a spring portion bowed outwardly of the attachment plane, the `bowed spring portion being deformable by linger pressure to lengthen the leg and being operative when released to resiliently retract the end of the leg.

7. A fastener composed of a single piece of Aspring metal, said fastener comprising: a hub portion for attachment to a member to be fastened, the hub establishing an attachment plane at which the' fastener engages the member to be fastened, a pair of elongated spaced legs extending from the hub in side-by-side relationship, latching formations on the ends of the legs for telescopic latching with a complementary member, and a xedly-pos'itioned bridge connecting the legs at a location remote from both ends of both legs, a longitudinal zone of each leg being being operative when released to resiliently re-y formed as a spring portion bowed outwardly of the attachment plane, the bowed spring portion being deformable by nger pressure to lengthen the leg and being operative when released to resiliently retract the end of the leg.

8. A fastener composed of a single piece of stamped sheet steel, hardened and tempered, said fastener comprising: a pierced hub for attachment by a rivet to a member to be fastened, the hub establishing an attachment plane at which the fastener engages the member to be fastened, means connected with the hub and projecting inwardly from the attachment plane for engagement with the member to hold the fastener against rotation about the rivet, a pair of elongated spaced legs extending from the hub in edge-to-edg'e relationship, latchng formations on the ends of the legs for telescopic latching with a complementary member, and a xedlypositioned bridge connecting the legs at a location remote from both ends of both legs, a longitudinal zone of each leg being formed as a spring portion bowed outwardly of the attachment plane, the bowed spring portion being deformable by finger pressure to lengthen the leg and tract the end of the leg.

EDWARD L. JOHNSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 126,819 Marvil May 14, 1872 345,337 Tollner July 13, 1886 2,023,095 Parker Dec. 3, 1935 2,058,733 Smith Oct. 27, 1936 2,097,993 Abbott et al. Nov. 2, 1937 2,144,910 Churchill Jan. 24, 1939 2,151,896 Carter Mar. 2a, 1939 2,169,708 OCall Aug. 15, 1939 2,284,004 McCurdy May 6, 1942 2,353,933 Schneider July 18, 1944

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