Abstract:
Hollow ornaments in the form of closed links with ornamental and functional openings for producing rings, earrings, pendant bangles necklaces or bracelets and in the form of continuous array of closed links with functional and ornamental openings, which are joint free; and process for producing them.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to hollow ornaments in the form of closed links in the shapes of bracelets and rings, and their arrays, and process of producing them. 
       OBJECTIVE 
       [0002]    The objective is to invent hollow jewellery in the form of bracelets, bangles, necklaces rings, earring, pendant and chains and a process of producing hollow jewellery. 
         [0003]    Another objective is to invent a process of producing hollow jewellery in the form of array of links which are passing through one another and yet are free from joints and thus are free from joining marks normally unavoidable in making chains or arrays of links. 
       BACKGROUND OF THE INVENTION 
       [0004]    Jewelry manufacturing has the challenge of aesthetics and finish besides robustness and other manufacturing issues. The processes used are by and large same as those used for any metal work of intricate shape. Investment casting is one of the most common techniques deployed for jewellery manufacture in volumes. U.S. Pat. No. 1,398,706 describes this. 
         [0005]    Jewelry is worn for ornamental purpose and weight of jewelry is often a detrimental aspect for two reasons—it makes the wearer feel the weight and also increases the cost without really adding value. 
         [0006]    Hollow jewelry therefore becomes a natural choice. One such hollow jewellery is disclosed in Patent Application No: 2024/MUM/2008. Hollow jewellery solves both problems—weight as well as cost, however producing hollow jewellery has the compounded challenge of maintaining aesthetics, finish and robustness. Particularly the ugly trail of the welding joint of the components reduces the ornamental value and therefore acceptability significantly. 
         [0007]    Jewelry products like Chains and continuous links need to be assembled by interlinking and joints are detrimental here again. Patent BG66006B1 (Publication Number) describes such processes which involves several mechanical operations and skill. 
         [0008]    Production of Jewelry which is hollow as well as continuous has to meet all the challenges. Our inventiveness lies in minimal mechanical operations leading to high quality jewellery with consistent finish. 
       STATEMENT OF INVENTION 
       [0009]    Our invention is hollow ornaments and the process to produce them so that there are neither cuts nor joints on the closed links or the array of closed links. 
         [0010]    The links of the array of hollow jewellery have ornamentally designed functional openings through which filler material can be filled in and out to achieve the hollowness. 
         [0011]    The jewelry is in precious metal which is made by casting in pattern of refractory material. The pattern is made by using low melting point soft material which is directly obtained from computer generated model. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0012]      FIG. 1  shows the jewelry in the shape of array of links producible from this process. 
           [0013]      FIG. 2  shows a typical embodiment of individual links with functional and ornamental openings; and relative placement in CAD 
           [0014]      FIG. 3  shows the array of closed links (whether in model form, in wax or in cast metal) having support network with plurality of interconnections constraining movement of individual closed links w.r.t. one another. 
           [0015]      FIG. 4  shows the tree of plurality of hollow model of jewellery in soft material of low melting point. 
           [0016]      FIG. 5  shows the tree in casting flask. 
           [0017]      FIG. 5A  shows a sectional view of the casting flask. 
           [0018]      FIG. 6  shows different illustrative shapes of discrete closed links with functional and ornamental openings. 
           [0019]      FIG. 7  shows the flowchart of the complete process of producing Hollow ornaments. 
       
    
    
     DETAILED DESCRIPTION OF INVENTION 
       [0020]    The preferred embodiment of jewellery as per our invention is now being described with the help of drawings. It is to be noted that virtually unlimited number of shapes can be created using the concept of this invention and therefore no shape described here is to be misconstrued as limiting the invention. 
         [0021]    The chain ( 10 ) with several links ( 2 ) is firstly drawn on computer aided design (CAD) systems dealing in three dimensional modeling, to produce virtual model identical in shape and thickness. There are several such design systems available, Rhino, ProE, CATIA, AutoCAD, Solidworks etc. are just to cite few. 
         [0022]    Every link ( 2 ) is modeled with required outer shape and dimension and required thickness. Each link is close in shape and therefore does not have start or end. Several openings ( 8 ) are made in each link which are either artistic shape or regular or irregular geometrical shapes. These openings ( 8 ) are of significance in the process of producing jewellery as shall follow. 
         [0023]    The links ( 2 ) is assembled virtually on the CAD systems in the required array form and this is possible since these are virtual links and therefore pass through one another without material obstruction. 
         [0024]    Further, connectors ( 12 . 2 ) are modeled between the insides of the links. Main support ( 12 ) is modeled between first and last link and supports ( 12 . 1 ) are modeled on every link modeled and assembled transverse i.e. substantially at 90 degrees w.r.t. first and last link. The cross-section and dimensions of main support ( 12 ), supports ( 12 . 1 ) and connectors ( 12 . 2 ) are derived such that the chain ( 10 ) maintains the shape even when cast in metal, particularly precious metals like gold, silver, platinum, bronze. 
         [0025]    The CAD systems are capable of producing output in different forms like print binary or drawing exchange format (DXF) or stereo lithographic format (STL). STL format is the format usable as an input to three dimensional (3D) printing machines. 3D printing machines are known to “print” i.e. produce the CAD model using materials which have low melting point—like wax, polyethylene, Acrylonitrile butadiene styrene (ABS). Our inventive process also requires low surface hardness and therefore physical solid model ( 20 ) is obtained by inputting wax or equivalent material. 
         [0026]    The physical solid model is adequately hard to retain the complete shape. Diamonds or precious stones are pushed into the surface of links ( 2 ) and the diamonds or stones stay there as they are eventually required to, in the jewellery in precious metal, since wax or equivalent material displaces itself and holds the diamonds or precious stones by ingressing onto the edges all around the diamond or precious stone and into any ridges in them. 
         [0027]    Plurality of such solid models ( 20 ) are grouped together using anchors ( 30 . 1 ) around pillar ( 30 ) which is erected in a rigid base ( 25 ). This formation is installed in a casting flask ( 40 ) of metal with big holes ( 45 ) all around. The holes ( 45 ) are initially temporarily closed by wrapping a thin plastic film coated with adhesive so as to keep the plastic film in its place. 
         [0028]    The casting flask ( 40 ) is filled with gypsum plaster, also known as plaster of Paris, lime plaster, or cement plaster or equivalent material which has refractory properties i.e. it should be able to withstand upto 1000° C. temperature without scorching or burning away and should not produce fumes when heated. 
         [0029]    The refractory material is filled in low viscosity form by making its dilute solution in water such that it can completely fill in the hollow part of every link through openings ( 8 ) provided. 
         [0030]    After the refractory material solidifies, the casting flask is heated so as to melt away the material used for making solid model ( 20 ). 
         [0031]    Precious metal in the molten form is poured in the casting flask and plurality of jewellery ( 20 ) is obtained, with diamonds and precious stones studded robustly. 
         [0032]    The plurality of jewellery ( 20 ) is separated from the pillar ( 30 ) by manually cutting away the anchors ( 30 . 1 ). Next, main support ( 12 ) and supports ( 12 . 1 ) are manually cut away. Lastly, all connectors ( 12 . 2 ) are manually removed. 
         [0033]    This results into links freeing themselves and therefore the hollow jewellery in the form of array of links free from any joints. 
         [0034]    The array of links can be made using any shape of closed links ( 2 . 1 ,  2 . 2 ,  2 . 3 ,  2 . 4 ,  2 . 5 ,  2 . 6  are just few of the unlimited possible shapes). 
         [0035]    Likewise, the process is usable in the manner described above, for mass producing discrete closed links, rings, earrings, pendant bangles necklaces or bracelets or by whatever name it might be known. 
         [0036]      FIG. 7  describes the Process in the form of a flowchart.