US2841825A - Negative pattern and hollow mold for casting compound reflector members - Google Patents

Description

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B. J. PIQUE NEGATIVE PATTERN AND HOLLOW MOLD FOR CASTING COMPOUND REFLECTOR MEMBERS Original Filed March 19. 1951 July 8, 1958 I N VEyNgHQ FIG?) United States Patent NEGATIVE PATTERN AND HOLLOW MOLD FOR CASTING COMPOUND REFLECTOR MEMBERS Baudilio Jesus Piqu, Marianao Township, Cuba Original application March 19, 1951, Serial No. 216,367, now Patent No. 2,719,327, dated October 4, 1955. Divided and this application August 19, 1954, Serial No. 450,982

2 Claims. (CI. 18-34) My invention relates to improvements in negative pattern and hollow mold for casting compound reflector members. This invention comprises subject matter disclosed in my copending application Serial No. 216,367, filed March 19, 1951, for Centrifugal Casting Processes and Apparatus for Casting True Paraboloidal Convex Surface Patterns, now Patent No. 2,719,327, issued on October 4, 1955, of which this is a divisional application. It has been designed more particularly as a device for making commercially practicable the adaptation of the complementary parts combined in my invention described and claimed in the United States Letters Patent No. 2,501,140, issued March 21, 1950, for Electric-Light Projecting Reflector.

The present invention provides a hollow mold comprising a negative pattern with true half paraboloidal convex surfaces for casting compound reflector members.

One of the advantages of these negative patterns is that they are made with accurately formed paraboloidal convex surfaces.

Another advantage of these negative patterns and hollow mold are their adaptation to manufacture compound reflector members made directly by simple casting.

The construction of these negative patterns comprises a centrifugal casting process in apparatus for casting true paraboloidal convex surface patterns.

It is known that the best concave surface produced with extreme accuracy is the paraboloid of revolution, because when a liquid body is contained in a receptacle which rotates uniformly, the surface of the liquid takes the form of an accurate paraboloid. The natural surfaces of liquids in an absolute or relative state of repose are extremely accurate. When this liquid consists of a solid in fused condition, and is cooled while continuing at the same angular velocity, the liquid body will solidify conserving the paraboloidal surface.

When two bodies having different physical conditions referring to their specific weights and fusion points, are contained in fused condition within a receptacle, the heavier liquid will be under the lighter liquid. When these liquids are in absolute or relative state of repose, the liquid joint surface will have equal shape than the top liquid surface. When these two liquids are contained in a receptacle which rotates uniformly, the top liquid surface and the liquid joint surface take equal forms of accurate paraboloid. If the receptacle continues at the same angular velocity while the liquids are cooling, these liquid bodies will solidify comprising paraboloidal surfaces accurately formed.

The provision of an apparatus for centrifugal casting comprising a receptacle that rotates uniformly having means for holding determinate quantities of two melted materials according to the angular velocity applied to said receptacle, and means for making a pair of half patterns having an inner plane border limiting half convex paraboloids and a bevel border of uniform thickness at their outer peripheries. The melted materials having different physical conditions with each other, referring to their spe- 2,841,825 Patented July 8, 1958 cific weights and fusion points, will form separable composite casting with true paraboloidal surfaces. The apparatus may be so operated in a centrifugal casting process that each pair cast in the apparatus will have a different convex curvature from every other pair cast in the same apparatus and having the same thickness of bevel border at their outer peripheries.

As wrought concave and convex surfaces are not as accurate as it is desired for patterns, one of the objects of my improvement is to form negative patterns having true half paraboloidal convex surfaces.

Another object is to provide a negative pattern constituted with two different half patterns having each one halves an inner plane border limiting half convex paraboloid and a bevel border at their outer periphery. Said both dilferent half patterns being joined with each other through their inner plane border and thus being fitted and attached throughout their peripherical bevel border on a bevel ring support, to be used as compound surface pattern in pressing apparatus or in hollow mold.

A further object of my invention is the provision of a hollow mold adapted to manufacture compound reflector members by a simple casting.

Referring to the drawings: Fig. 1 presents a vertical sectional view of a centrifugal casting apparatus for making a pair of half paraboloidal patterns; Fig. 2 is a sectional view of a hollow mold showing the object of this invention; and Fig. 3 is a sectional view through the line 3-3 of Fig. 1. Similar numerals refer to the same or similar parts through the figures.

An apparatus for centrifugal casting comprising a receptacle A having a curved base 1 with the inner side forming a rippled paraboloidal surface 2. Said receptacle A is provided with a cylindrical end 4 having a conical edge at the periphery thereof.

A thin blade 9 having a paraboloidal border is fitted and attachedby its border on the inner paraboloidal rippled surface 2 of said receptacle A.

A rotor axle 3 attachedto the receptacle A, is placed vertically in a machine not shown in the drawings, which rotates uniformly together with the receptacle A around its symmetrical axis.

A melted material 10 is put within the receptacle A to be adapted as an adjustable mold according to the angular velocity applied in the apparatus to said receptacle A.

A conical ring 5 having an inner sharp edge 6, is assembled with said cylindrical end 4 at the periphery of receptacle A, being fitted by means of a ring flange 7.

Another melted material 11, having lighter specific weight and higher fusion point than the first one, is put Within the receptacle A for casting a pairof half patterns 1111 upon said first melted material 10.

The cylindrical end 4 with its conical edge is adapted at the periphery of receptacle A to regulate the amount of melted material 10. The conical ring 5 with its inner sharp edge 6 is adapted upon the cylindrical end 4 of receptacle A to regulate the amount of melted material 11 and to perform a bevel border 14 at the outer peripheries of the casting patterns. 1

An annular pan 8 is located separately surrounding the rotor receptacle A.

When the receptacle A, without the conical ring 5, rotates with predeterminate velocity having within it the melted material 10, this material 10 will flow upward -by receptacle A, to be shaped according to the concave curva- 3 ture required to constitute an adjustable paraboloidal mold.

After this, fitting the conical ring 5 upon the cylindrical end 4 of receptacle A, and then, when said receptacle A rotates with the same predeterminate velocity, the other melted material 11 having lighter specific weight and higher fusion point than the first material 10, is put within the receptacle A and upon the melted material 10, whence, the second melted material 11 flows upward by centrifugal force and the excess of this material 11 will be spilled out from inner sharp edge 6 of conical ring 5 to the annular pan 8, and an appropriate quantity of said material 11 is retained by said conical ring 5, according to the angular velocity with which said receptacle A is rotated, to be shaped havingtheir contours defined. The liquid joint surface 12 will be a predeterminate true paraboloidal surface as same as the top liquid surface 12.

When the materials and 11 are cooled by lowering their temperature between the temperatures of fusion points of both materials 10 and 11, the material 11 having higher fusion point than the material 10, will be solidified, and the material 10 will continue melted, forming separable composite casting. In this condition, after take out the conical ring 5, the solidified material 11 may be taken out by a suction cup.

The thin blade 9 is adapted in the receptacle A to disjoint halves of said casting pattern 11 through a plane holding the axis of paraboloidal surface 12, and for performing an inner plane border 9 limiting half convex paraboloids 12-12 and thus obtaining a pair of half patterns 11-11.

Furthermore, making another pair of half patterns 11'11', by distinct angular velocity of receptacle A than that of the first patterns 11-11, after having been corrected the quantity of melted material 10 according to the angular velocity applied to the receptacle A in accordance with the curvature'required in such pair of half patterns 11'-11'.

Each different pair of half patterns 11-11 and 11'-11 will have a bevel border 14 with the same uniform thickness at their outer periphery, it shaped by the conical ring 5, and an inner plane border 9' limiting half paraboloids throughout a plane comprising the axis of said half paraboloids, it shaped by the thin blade 9.

Now, two different half patterns 11 and 11', taken from two different pairs of half patterns, will be joined through their inner plane border 9' and welded together to constitute a compound negative pattern having two half convex paraboloids 12 and 13 with different convex curvature and displaced from each other along their paraboloidal axis, and a meniscus plane, as it is shown in Fig. 1 between the paraboloidal sections 12 and 13, will be conformed between the inner periphery of both displaced half convex paraboloids 12 and 13 and comprising their paraboloidal axis according to the inner plane border 9' of said half patterns 11 and 11. These half patterns 11 and 11 will have their peripherical bevel border 14 coinciding in conical ring section.

This negative pattern 11-11, which comprises true half paraboloidal convex surfaces 12-13, will be used as compound surface pattern in pressing apparatus or in hollow mold as is shown in Fig. 2.

A plate base having a conventional ring support 15 with a bevel ring surface. The compound negative pattern 11-11, as described, is adjusted on the bevel ring surface of ring support 15, throughout its peripherical bevel border 14.

A cover member 16 having an inner paraboloidal concave surface 17 and a bevel border at-its periphery. The

cover member 16 is adapted, throughout its peripherical bevel border 14, on the ring support 15, inwalling thenegative pattern 11-11 and the bevel ring surface of ring support 15 in a hollow mold 19.

7 4 member 16 will be inwalling the negative pattern 11-11 and near to face with their displaced half convex paraboloids 12-13.

The bevel ring surface of ring support 15 will form the end of said hollow mold 19, adapted between the outer periphery of the inner paraboloidal concave surface 17 of cover member 16 and the outer periphery of the two half convex paraboloids 12 and 13 of negative pattern 11-11.

Thecover member 16 has a hole 18 communicating the hollow mold 19 with the exterior.

This hollow mold 19 comprises: a conventional ring support 15 having a bevel ring surface, a negative pattern 11-11 comprising two half convex paraboloids 12 and 13 having different curvature displaced from each other along their paraboloidal axis, said negative pattern 11-11 is adjusted on the bevel ring surface of ring support 15 coinciding their half convex paraboloids 12-13 with the bevel ring surface. of ring support 15 throughout their outer periphery, a meniscus planercon-v formed between the inner periphery of said displaced half convex paraboloids 12-13 and comprising their paraboloidal axis, and a cover member 16 having an inner paraboloidal concave surface 17 inwalling said negative pattern 11-11 and substantially near to face with said displaced half convex paraboloids 12-13, the cover member 16 is adjusted on the ring support 15 inwalling the bevel ring surface of said ring support 15. The

' casting is made through the hole 18 into the hollow mold Theinner paraboloidal concavesurface 17 of the cover 19 for making compound reflector members.

What I claim is:

1. The combination, in a hollow mold comprising a ring support and a cover member, of a negative pattern, comprising two half convex paraboloids having different curvature displaced from each other along their paraboloidal axis, and a meniscus plane conformed between the inner periphery of said displaced half convex paraboloids and comprising their paraboloidal axis, with an inner paraboloidal concave surface in said cover mem-, ber inwalling said negative pattern near to face with said:

displaced half convex paraboloids, and a bevel ring surface in said ring support located between the outer periphery of said half convex paraboloids and said inner paraboloidal concave surface, and thus said hollow mold being adapted for casting compound reflector members.

2. In a hollow mold comprising a conventional ring support having a bevel ring surface, the combination of a negative pattern comprising two half convex paraboloids having different curvature displaced from each other along their paraboloidal axis, and a, meniscus plane conformed between the inner periphery of said displaced half convex paraboloids and comprising their paraboloidal axis, with a cover member having an inner paraboloidal concave surface inwalling said negative pattern and near to face with said displaced half convex paraboloids, said negative pattern having their half convex paraboloids coinciding with the bevel ring surface of said ring support throughout their outer periphery, said cover member adapted on the ring support with its inner paraboloidal concave surface inwalling the bevel ring surface of said ring support, and thus said hollow mold being adapted for casting compound reflector members.

References Cited in the file of this patent UNITED STATES PATENTS

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