US2066171A - Lamp bracket - Google Patents

Description

A. H. BELL LAMP BRACKET Dec. 29, 1936.

Filed-Feb. 21, 1955 /NVENTO,Q,

- ATTORNEY H M w Patented Dec. 29, 1936 UNITED STATES PATENT OFFICE LAMP BRACKET Application February 21, 1935, Serial No. 7,480

10 Claims.

My invention pertains to an improved construction of arms for bridge lamps and the like, by which the cost of constructing such arms is materially reduced, without weakening the arms or detracting from their appearance.

Armsv of the kind under consideration, are usually employed in electric lamp constructions, to support a lamp bulb or bulbs'in pendent position, at some distance laterally from the pedestal or spindle of the lamp construction, to the end that the light may be projected downwardly without obstruction of any kind, for example, upon a table, or for reading purposes. As a result, the arm, beginning at its lower or supported end, extends upwardly and vertically, then is curved to effect the desired lateral displacement from the part supporting the arm, and then extends downwardly to its upper end, to support the lamp socket or sockets employed, and also the shade that may be used.

As far as I am aware, it has been the practice heretofore, in constructing arms of the kind described, to make a built up construction, as follows. A tube of suitable metal, for example, brass, of substantially the length of the arm from end to end, is bent to the curvature and shape to effect the desired relation of the ends of the arm to each other, both vertically and horizontally. Then the bent tube is placed in a metal mould fitting the tube and provided with a cavity surrounding the tube, said cavity having the size and shape of ornamentation to be placed around the tube, and suitable metal in molten condition, for example, white metal, is poured into the mould. Thus the ornamentation desired on the tube where it passes through the mould cavity, is produced. This casting operation is repeated for each separate ornamentation on the tube. This procedure produces arms that are satisfactory in use, but it is open to serious objections from the standpoint of economy in manufacture. The material of the tube is relatively expensive; the arms must be bent by accurate and expensive dies, to insure that they will accurately fit the moulds; each mould must be of metal to properly cast and finish the corresponding ornamentation; and each arm must be handled many times and subjected to many operations, before it is completed. Furthermore, the ornamental cast part is solid instead of hollow as in the arms of the present invention thus limiting the size of the ornamental sections because of the otherwise excessive weight.

By my invention, I eliminate the greater part of the cost of producing arms as described, by casting each arm as a single integral structure of suitable metal, for example, white metal. Furthermore, but one operation is required in making each arm, to wit, casting the entire arm as a single, integral structure, in a mould that is preferably of metal, to facilitate quantity production at a rapid rate, and at the same time to impart to each arm an exact size and shape and a finish so good as to require no subsequent finishing operation. I thus eliminate most of the operations heretofore required in producing such arms, and materially reduce the necessary tool cost.

Furthermore, by my invention, I reduce to a minimum, the amount of casting metal employed by using the slush method of casting consisting briefly in pouring the molten metal into a metal mould and then when the molten metal engaging the mould has been set and chilled, pouring from the mould the casting metal that is still in molten condition, leaving in the mould a hollow casting which externally is a counterpart of the mould. The process of so moulding my improved lamp arms, which constitutes a part of my present invention, consists of providing a metal mould for the desired arm, having open ends and provided with extending horns open to the atmosphere, filling the mould with the molten metal, and then, after the molten metal has chilled and set against the mould, turning the mould in the manner required by the particular form or" the arm being cast, to flow the still molten metal from the innermost parts of the mould, and then continuing the turning of the mould, in the same direction progressively from the remaining parts of the mould, until finally the molten metal is completely drained through one end of the tubular casting in the mould, care being taken in turning the mould, to avoid locking in the mould,. any of the still molten metal, which would produce a solid cast structure instead of a tubular structure, at the point or points of locking. The arms produced by the process just described, besides being integral structures from end toend, are also tubular from end to end, including the ornamentation involved, and in addition they possess the requisite strength with a minimum amount of metal. Heretofore, unless special. and expensive shapes of tubes were employed, the parts of the built-up arms where the bent tubes were exposed to view, were necessarily of uniform size or diameter, whereas with my improved process, the resulting arms may be of uniform size or diameter where they are not ornamented,

they may be tapered, or they may have any other desired conformation. In fact, my improved arms may have practically any desired size and shape at any point, regardless of what the size and shape may be at other points.

My invention will be best understood by reference to the accompanying drawing illustrating a preferred embodiment thereof, in which Fig. 1 illustrates my improved arm in side elevation, supported on a lamp spindle,

Fig. 2 shows in a View similar to Fig. 1, a modified form of my improved arm construction,

Fig. 3 shows in side elevation, a lamp arm of the built-up type heretofore used, together with the parts employed in making the assembly,

Fig. 4 shows in side elevation, a modified form of lamp arm of the built-up type heretofore used, and

Fig. 5 shows in vertical, central, sectional view to an enlarged scale, my improved arm illustrated in Fig. 1.

Similar numerals refer throughout the several views.

As shown in Fig. 5, the arm H] is an integral casting from its lower end to its upper end, which ends are provided with threads l I and [2 respectively, for connection as shown in Fig. l, with a supporting spindle l3 and lamp socket M, the spindle [3 in turn being supported by a base l5. As shown in Figs. 1 and 5, the arm 10 is provided above its lower end, with an ornamental branching member in the form of a scroll l6, which, as shown in Fig. 5, is integral with the arm ID and closed at its outer end. As shown in Fig. 5, the arm [0 is hollow from end to end, and the scroll I6 is also hollow, and, moreover, as a result of casting the arm by the slush method as above described, the wall thickness throughout may be substantially uniform, even at the larger ornamental portions IT, l8 and I9, thus reducing to a minimum, the weight of cast metal required to impart to the arm, the requisite strength. It will be observed that, if the internal diameter of the tubular arm were substantially uniform throughout and if the scroll l6 were solid, considerably more cast metal would be required, materially increasing the cost without advantage of any kind.

In considering the making of the arm ID, the lower end portion of the arm, represented, generally by the ornamental portions I1 and I8, is referred to herein as the ascending portion, the upper end portion represented generally by the ornamental portion I9, is referred to herein as the descending portion, opening in the same general direction as the ascending portion, and the curved portion of the arm between said ascending and descending portions, is referred to herein as the intermediate portion of the arm, it being understood that these portions merge imperceptibly into each other, without definite demarcation between them.

In casting arms of the kind shown in Fig. 5 by the slush method, the difiiculty is to avoid rupture of the cast metal, resulting from the cooling contraction of the white metal employed, which contraction is high. As to the method of casting my improved arms, my present inven-' tion is a further development of the invention disclosed in my copending application, Serial No. 757,424, in which I describe means for distributing the internal strains of cooling in long tubular slush castings, to insure that said strains shall not at any point in the casting, be as great as the ultimate strength of the cooled cast metal.

to similar parts My present method, besides involving the manner of handling the mould above described, to drain the still molten metal from the chilled and set tubular wall of the arm, involves also constructing the mould so that it is in part the counterpart of the intermediate or curved portion of the arm, as a result of which, when the cast metal chills and sets against the mould, the chilled cast metal of said intermediate portion, presses so firmly against the mould, that the cast metal locks against the mould, and there is no movement of the chilled cast metal longitudinally of the mould cavity, at any point of said intermediate portion, even though said intermediate portion be of substantially uniform ex ternal cross-section throughout its length. Longitudinal movement in the mould of the intermediate portion as a whole, is prevented by the interlocking of the projecting ornamentation on the ends of the arm, with the mould. In this manner, the internal strains developed at any point in said intermediate portion, which for the arm illustrated, is its weakest portion, are restricted in their action, to the chilled cast metal in which they are developed, and there is no possibility of a transmission of 'saidinternal strains cumulatively, to other parts of the cooling arm. As the cooling cast metal has an ultimate strength greater than the internal strains of cooling developed in it locally at any point, rupture of the cast tubular arm on cooling, is avoided.

In Fig. 2, the arm Illa illustrated, is similar to the arm I 0, excepting that the scroll I6 is omitted, the arm Illa being otherwise made in the same manner and having the same advantages as the arm In. In Fig. 2, the arm Illa.

is shown as supported by the upper end of a spindle l3a, said arm. in turn supporting a socket I Act. The arm Illa is shown as provided with projecting ornamentation on its intermediate portion, which further insures the interlocking of the casting during its making, with the mould employed, to prevent the cumulation of internal strains in the chilled-cast metal, and rupturing the casting.

In Fig. 4, I illustrate one form of lamp arm of the class described, as heretofore constructed. As shown in this figure, a metal tube IDb, for example, of brass, extending substantially from end to end of the arm, is bent by suitable dies to the exact shape of arm desired. The bent tube is then placed in a mould fitting it, and part of the ornamentation, as I81), is cast around the tube, for example,'of white metal.

Then the bent tube is placed in another mould fitting it, and another part of the ornamentation, as 19b, is similarly cast around the tube. It will be observed that inaddition to the cost of the tube, and the'many operations of handling it involved, the amount of white metal required is large relatively, and correspondingly expensive, since the parts cast around the tube must be solid, and cannot be cast hollow between the outer surfaces ofsaid parts and the outer surfaces of the tubes In Fig. 3, I illustrate a means heretofore employed to decrease the amount of white metal required in making arms of the built-up type, from the amount of such metal required with the construction shown in Fig. 4. In Fig. 3, for purposes of comparison, the same ornamental effect is assumed as in Fig. 4, the difference being that the arm proper, consists of a bent tube lllc having ornamentation I and l-9c cast on and around it as described for the arm shown in Fig. 4, the part I80 being only the upper part of the ornamentation corresponding to the part l8b in Fig. 4. The remaining part i812 employed to complete the effect of the part 182), is a separate slush casting made in the usual way and requiring less metal than the corresponding part in Fig. 4. This saving, however, is off-set by the extra mould cast, and the additional operations of handling required. To complete the construction of Fig. 3, a pipe I30 forming the supporting member of the lamp spindle, is secured at its upper end, to the lower end of the arm, the part Ifid is slipped on the pipe I30 to rest against the lower end of the arm, and a finishing tube l3d is placed on the pipe I30 with its upper end against the lower end of the part ltd, in which position the parts are securely held by the base (not shown) supporting the pipe I30.

.The particular devices employed to secure the arms to their supporting structures, and to secure the sockets to the arms are not shown, as there are various forms of such devices known to the art, and any of such devices may be used as desired.

The over-all length of arms of the kind above described is usually from 12 to 24 inches, and the horizontal displacement of the upper end of the arm from the lower end thereof, is usually from 6 to 8 inches.

While I have shown my invention in the particular embodiments above described, it will be understood that I do not limit myself thereto, as I may employ equivalents thereof known to the art at the time of the filing of this application, without departing from the scope of the appended claims.

Having thus described my invention, what I claim is:

1. A lamp bracket having an eifective length adapting it to the purposes described, which bracket includes successive portions extending in different directions and is adapted to be secured to a supporting standard, said bracket comprising a homogeneous white metal unitary slush casting having a continuous passage therethrough resulting from the casting operation, said continuous passage being adapted to receive electric conductors.

2. A lamp bracket having an effective length adapting it to the purposes described, which bracket includes successive portions extending in difierent directions and is adapted to be secured to a supporting standard, said bracket comprising a homogeneous white metal unitary slush casting having an integral decorative branch and a continuous passage therethrough resulting from the casting operation, said continuous passage being adapted to receive electric conductors, said passage continuing into said branch.

3. A lamp bracket having an eiiective length adapting it to the purposes described, which bracket includes successive portions extending in different directions and is adapted to be secured to a supporting standard, said bracket comprising a homogeneous white metal unitary slush casting having a continuous passage therethrough resulting from the casting operation, said continuous passage being adapted to receive electric conductors, said bracket being tapered longitudinally.

4. A lamp bracket having an effective length adapting it to the purposes described, which bracket includes successive portions extending in different directions and is adapted to be secured to a supporting standard, said bracket comprising a homogeneous white metal unitary slush casting having a continuous passage therethrough resulting from the casting operation,

said continuous passage being adapted to receive electric conductors, said bracket having spaced openings communicating with said passage for connection respectively with a standard and with a lamp socket.

5. A lamp bracket having an effective length adapting it to the purposes described, which bracket includes successive portions extending in different directions and is adapted to be secured to a supporting standard, said bracket comprising a homogeneous unitary slush casting having a continuous passage therethrough resulting from the casting operation, said continuous passage being adapted to receive electric conductors.

6. A l-ainp bracket having an effective length adapting it to the purposes described, which bracket includes successive portions extending in diiTerent directions and is adapted to be secured to a support, said bracket comprising a unitary slush casting having a continuous passage therethrough resulting from the casting operation, said continuous passage being adapted to receive electric conductors, said bracket having spaced openings communicating with said passage for connection respectively with a support and with a lamp socket.

'7. A lamp bracket having an eiTective length adapting it to the purposes described, which bracket includes successive portions extending in diiierent directions and is adapted to be secured to a support, said bracket comprising a white metal unitary slush casting having a continuous passage therethrough resulting from the casting operation, said continuous passage being adapted to receive electric conductors, said bracket having spaced openings communicating with said passage for connection respectively with a support and with a lamp socket.

8. A lamp bracket having an effective length adapting it to the purposes described, which bracket includes successive portions extending in different directions and is adapted to be secured to a support, said bracket comprising a unitary slush casting having a continuous passage therethrough resulting from the casting operation, said continuous passage being adapted to receive electric conductors, said bracket having spaced openings communicating with said passage for connection respectively with a support and with a lamp socket, said bracket being tapered longitudinally.

9. A lamp bracket having an effective. length adapting it to the purposes described, WhiCh' bracket includes successive portions extending in different directions and is adapted to be secured to a support, said bracket comprising a unitary slush casting having a continuous passage therethrough resulting from the casting operation, said continuous passage being adapted to receive electric conductors, said bracket having spaced openings communicating with said passage for connection respectively with a support and with a lamp socket, said bracket having an over-all length greater than twelve inches and the straight-line distance of said openings from each other being greater than five inches.

10. A lamp bracket having an effective length adapting it to the purposes described, which bracket includes successive portions extending in different directions and is adapted to be secured connection respectively with a support and with a lamp socket, said openings having screw threads for connection with said support and said lamp socket.

ALLAN H. BELL.

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