US2286085A - Reflector unit and method of making said unit - Google Patents

Description

June 9, 1942. J. c. HAG GART, JR

REFLECTOR UNIT AND METHOD OF MAKING SAID UNIT Filed July 5, 1940 INVENTVOYR J'omv (3 654663487, fe.

ATTORNEY atet june 9 I This invention relates to the art of autocollimating reflecting units and especially reflectors which comprise a number of individual reflecting elements integrally joined to form a composite-reflecting area. Such reflectors are usually in the form of discs of glass or plastic material with the individual reflecting elements so closely emaciated that the eifect is that of a single large reflector. These elements may be of the lenseflector type or they may be of the a hole 'in which the unit is inserted. The standard includes a backing member to hold the unit in place.

The problem in connection with the assembly of the reflector and its holder is to obtaina permanent moisture tight seal and avoid the production of strains which will warp the reflector and impair its efficiency.

As is well known these reflectors are provided with a. rearwardly extending flange which sits in the cup-like holder and is peripherallyclamped between the bottom of the holder and a turnedover lip or flange. The production of this clamp.- ing engagement is aptto'create a radial stress which will warp the disc. I have disclosed a way to avoid this in my prior Patent No. 2,255,748

- issued September 16, 1941, the principal feature which is the provision of a clearance between the flange of the cup and the periphery of the disc. In that construction the center of the bottom of the cup is raised and fits into the disc flange, thereby centering the disc with respect to the cup flange, and the gasket receiving annular portion surrounding the raised center is flat. In the assembly the cup flange is crimped over the gait, n, warmers, is. a; ta service Ccrperation, a aeration or 5, 19%, Serial No; 343,995

(case-rs) In accordance with the present invention the cup member is'so preliminarily shaped that a resilient force is created duringthe assembly These are cup-shaped which operates to bias the turned over edge of the cup flange toward the shoulder and reactively to cause the cup to bear especially-against the gasket at the inner comer of the reflector flange and thus effect a tight seal.

More particularly the annular gasket receiving part of the holder is formed with a downward and outward inclination so that as it is drawn up into the plane of the rear face'of the disc flange it bends about the inner corner of the reflector flange and is held there against .its resilient reaction by the engagement of the turned over edge or lip 'of the flange with the shoulder. lhe opposing forces are-therefore between the corner which constitutes the fulcrum and the shoulder.

As a consequence the maximum compression of the gasket is at the comer.

I shall now describe the method with particular reference to the construction and steps illustrated in the accompanying drawing and shall thereafter point out the invention in claims.

Fig. 1 is a cross section of the component elements at the flrst stage of the assembly.

Fig. 2 is a similar view at an intermediate stage. Fig. 3 is a similar view at the completion of the operation.

- Fig. 4 is a plan partially in section of the completed unit.

shouldered front edge of the disc and the flnal compression is obtained by closing down the surrounding bead.

While this method practically eliminates the formation of warping stresses, it has been found that the permanence of the seal is not entirely reliable. This invention therefore contemplates a modification of that method.

The reflector I is a disc of plastic or other glass like composition, slightly meniscus in form.

and is shown as having tetrahedral formations on its rear face of the construction disclosed in the Stimson Patent No. 1,807,350. For mounting purposes it is provided with a rear flange 2 that has a circumferential extension beyond vthe boundary of the reflecting surface forming a front shoulder 3.

The holder is a metallic cup member 4 the diameter of which is somewhat greater than that of the reflector. As initially formed it has a surrounding flange 5 that joins the bottom by a projecting bead 6. The center part I of the bottom of the holder is raised and is joined by a flaring neck portion 8 to the surrounding annular portion 9. The parts are so proportioned that the raised center with its flaring neck portion fits up into the back of the reflector and centers it, the inner corner of the reflector flange op-.

posing the bottom of the neck. Theannular portion a is initially formed at a substantial inclination to the general plane of the unit, as shown in Figs. 1 and 2.

sults in anniform production.

I l. The-method of making a 'dered peripheral flange of the-reflector is resil- -iently held between the annular portion of the overlaps the neck portion 8, the outer diameter being such that it just fits within the flange 5, and is thereby centered as shown in Fig. 1. The reflector I is then placed centrally into the holder l in which position theinner edge of its flange face rests upon the gasket near its inner edge.

1 A forming die (not shown) of proper shape is brought to bear upon the-top edge of the flange 5. The axial movement of this die toward the reflector crimps the edge over to form the lip 50 overlying the shoulder 3. This movement in opposition to the backing member for the holder.

first brings the lip into contact with the shoulder and from that point further movement, as it continues to turn over the flange .5, forces the reflector down, compressing the gasket at the line of contact. This conditionis illustrated in Fig. 2. Continued movement of the die substantiallyflattens the portion 9 againstthe backing member and completely centers the. reflector flange at the base of the neck portion. Meanwhile the lip 5a is caused to follow theshoulder 3 and is flattened until its inner periphery is adjacent the axial wall of the reflector forming the inner terminus of the shoulder. This is the flnal condition as illustrated in Figs. 3 and 4.

' The gasket I is probably under more or less equal compression at the terminal movement of the die, but there is bound to be a slight spring back leaving the portion 9 at a slight inclination.

. This spring back only that allowed by the lip a which is bent past its point of elasticity and is set. at substantially the flnal angle. While the gasket Ill is under substantial compression throughout, the moment about the angle of the stantial inclination to a plane perpendicular to flange 2 causes the reaction of the shoulder 3 on the lip 5a to urge the bottom of the holder against the gasket at the line of turning and therefore accentuates the compression on that line. As a .consequence the seal has proven to be satisfactory and this method of assembly re- It willbe understood that the component steps 1 of the method may be carried out in a manner other than that precisely described without de-' parting from the scope of ,the invention as pointed out in the following claims. I claim:

reflecting unit,

portion surrounding the raised. center at a substantial inclination to a plane perpendicular to the axis of the'holder so as to form the frustum of a cone with the base at the other periphery, seating 'the reflector coaxialiy within the holder with the rearface of the reflector flange opposing the said inclined annular portion of the holder and resting at its inner edge upon the said flaring neck portion, exerting a combined axial and radial force upon the outer edge of the holder flange in opposition to a backing member until the flange is turned over into engagement with the front face of the radially shouldered peripheral flange of the reflector, and then continuing the axial force until the inclined annular portion of the holder is brought into substantial parallelism with the rear face of the reflector flange to .put the said annular portion of the holder and the turned over flange thereof.

2. The method of making a reflecting unit comprising forming a, reflector having a rearwardly extending peripheral flange radially shouldered on its front face, forming a cupshaped metallic holder with a raised center having a flaring neck portion-and with the annular portion surrounding the raised center at a subthe said overlapping part of the gasket, exerting a combined axial and radial force upon the outer edge of the holder flange in opposition to a backing member until the holder flange is turned .over' into engagement with the. front face of the radially shouldered peripheral flange of the reflector, and then continuing the axial force upon the turned over holder flange and the reflector flange until the said annular portion. is brought into substantial parallelism with the rear face of the reflector flange thereby flexing the holder at the line of bearing of the inner edge of the reflector flange and putting the said annular portion of the :holder under tension so that the reflector flange and the gasket are resiliently'held under substantial compression between the annular portion of the holder andthe turned over flange thereof.

3. The method of making a reflecting unit comprising forming a reflector having a rearwardly extending peripheral flange radially shouldered on its front face, forming a cupshaped metallic holder with a raised center having a flaring neck portion and with the annular portion surrounding the raised center at a substantial inclination to a plane perpendicular to the axis of the holder so as to form the frustum of a cone with the-base at the outer periphery and with the wall folded back at the juncture of said outer periphery with the flange of. the holder to form a-peripheral bead, laying an annular gasket in the holder on the said inclined annular portion and partially overlapping the said neck portion, seating the reflector coaxially within the holder upon the gasket with its periphery spaced from the holder flange and with the inner edge of the rear face of the reflector flange upon the said overlapping part of the gasket, exerting a combined radial and axial force upon the outer edge of the holder flange in opposition to abacking member until the holder flange is turned over into engagement with the front face of the radially shouldered peripheral of the inner edge of the reflector flange and putting the said annular portion of the holder under tension so that the reflector flange and the gasket are resiliently held under substantial compression. between the annular portion of the holder and the turned over flange thereof.

4. The method of making a reflector unit comprising forming a reflector having a rearwardly extending peripheral flange radially shouldered on its front face, forming a cup-shaped metallic holder with a raised center and an annular portion surrounding the raised center'at a substantial inclination to a plane perpendicular to the axis of the holder so as to form the frustum of a a cone with the base at the outer periphery, seating the reflector coaxially within the holder with the inner edge of the reflector flange resting upon the said inclined annular portion, applying an axial force to the reflector and the holder to flex the said annular portion thereof at the line of contact with the inner edge of the reflector flange and put it under tension and bending the outer end of the holder flange overinto engagement with the outer face of the reflector flange to maintain the annular portion in its flexed position so thatthe reflector flange is resiliently held between the annular portion of the holder and the turned over flange thereof.

5. A reflector unit comprising a reflector element having a rearwardly extending peripheral flange radially shouldered on its front face, and a cup-shaped metallicholder, said holder comprising a peripheral flange with its outer end turned inwardly into engagement with said shoulder, a raised center fitting within the rearwardly extending reflector flange, and an annu-' plane perpendicular to its axis, thereby creating i comprising a reflector'element provided with a rearwardly extending peripheral flange radially shouldered on its front face, and a metallic cup member the bottom of which has a raised center and a surrounding annulus inherently conical in shape with the base of the cone at its outer edge, the cup member being applied to the reflector element with the peripheral flange seated in the annulus and the flange of the cup member turned down on the shoulder to an extent to flex the annulus about the inner edge of the peripheral flange and bring the annulus substantially in a plane perpendicular to its axis, thereby creating a moment about the inner edge of the peripheral flange and causing the reaction of the turned over flange andv the shoulder to urge the annulus into close engagement withsaid inner edge.

7. As an article of manufacture a reflector unit comprising a reflector element provided with a rearwardly extending peripheral flange radially shouldered on its front face, an annular gasket, and a metallic cup member the bottom of which has a. raised center and a surrounding annulus inherently conical in shape with the base of the cone at its outeredge,- the cup member being applied to thereflector element with the peripheral flange seated on the gasket in the annulus and the flange of the cup member turned down on the shoulder to an extent to flex the annulus about the inner edge of the peripheral flange and bring the annulus substantially in a a moment about the inner edge of the peripheral flange and causing the reaction of the turned over flange and the shoulder to substantially compress the gasket between the annulus and ripheral flange.

JOHN C. HAGGART, JR.

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