Interengaging rings puzzle
This invention relates to a puzzle which consists of a plurality of rings of rectangular cross-section which are in diameter and in width and are formed on their top and/or bottom end faces with grooves which are wider than the rings so that the latter can be fitted together to form a plane figure. 
     The known puzzles of this kind have the disadvantage that the rings can be fitted together only by placing one ring on the other. For this reason, the composite plane figure has only a relatively low stability and easily disintegrates into the several rings when the figure is grasped. 
     It is an object of the invention to eliminate the above-mentioned disadvantabge and to provide a puzzle of the aforestated kind which permits the compositie figure to be grasped without fear of its disintegration into individual parts. We realize this object, in accordance with our present invention, by providing a solid ring and one or more split rings each having a peripheral slot accommodating the solid ring, the latter having a generally radial groove for each split ring. Each face of each split ring is provided with one or more similar grooves enabling oppositely facing grooves of different rings to be assembled into an interfitting coplanar array with the solid ring passing through the slot of each split ring. 
     A particularly desirable embodiment of our invention comprises five rings, four of which have each a continuous slot whereas the fifth rings is inserted into all four slots in the composite figure. 
    
    
     The accompanying drawing shows by way of example an embodiment of the invention. In the drawing: 
     FIG. 1 shows the composite puzzle; 
     FIG. 2 shows the separate rings of the puzzle; and 
     FIG. 3 is a sectional view taken on line III--III in FIG. 2. 
     The puzzle shown in the drawing comprises five rings 1, 2, 3, 4, 5 which are provided with grooves 10-29. Some of these grooves, namely the grooves 10, 13, 16, 18, 21, 24, 26, 27, 28, 29, are formed in the top surfaces of the rings 1-5. The remaining grooves 11, 12, 14, 15, 17, 19, 20, 22, 23, 25 are formed in the bottom surfaces. Each of the split rings 1, 2, 3, 4, is formed at one point with a throughgoing slot 6, 7, 8 or 9, which permits these rings to be interlinked. The solid ring 5 is the locking ring. The grooves 10-29 and the slots 6-9 extend substantially radially and are slightly wider than the rings 1-5. 
     Before the rings are fitted together, they are first placed on a support in the manner shown in FIG. 2. The ring 2 is then interlinked with the ring 1, e.g., in that the ring 1 is pushed through the slot 7 of the ring 2. The rings 1 and 2 are then rotated relative to each other until the groove 17 is disposed over the groove 10 and the groove 12 is disposed over the groove 13. The rings 1 and 2 are then moved toward each other until they interengage at the grooves 17 and 10 and at the grooves 12 and 13 so that the rings lie in a plane. 
     The rings 2 and 3 are similarly connected in that the groove 22 is moved to a position over the groove 16 and the groove 14 to a position over the groove 18 after both rings have been interlinked. Thereafter, the two rings 3 and 4 are interlinnked and are then moved so that the groove 23 is disposed over the groove 21 and the groove 21 and the groove 19 is disposed over the groove 24. Finally the locking ring 5 is fitted into the rings 1-4, which are interlinked and which interlock at the grooves, 10,17; 12,13; 14,18; 16,22; 19,24; 21,23. For this purpose, the groove 11 is moved to a position over the groove 26, the groove 15 to a position over the groove 27, the groove 20 to a position over the groove 28 and the groove 25 to a position over the groove 29. The throughgoing slots 6-9 of the rings 1-4 are occupied by the ring 5, which is not weakened in its cross-section at these points. 
     Whereas each of the split rings 1 - 4 has at least one groove on each of its opposite faces, the solid ring 5 has all its grooves 26 - 29 on only one face to facilitate its assembly with the rings 1 - 4 already interlinked into a chain.