| abstract |
The invention relates to a building brick for use as an educational aid, a display device or in a constructional kit for children. The brick is in the form of a solid cube having one place face, a spigot or projection of rectangular cross-section on another face, the remaining faces each incorporating a socket to accept the projection or spigot of another similar brick, the projection or spigot and socket being so shaped that an interference fit is formed when two similar bricks are joined. By making the brick of unit dimension and unit weight it can be used in constructions of bricks, inter alia, to teach the concept of weight, length, volume and so on. It is made by a process comprising injection moulding the blocks from a stiffly resilient material in a die having substantially minimum draft necessary to facilitate withdrawal, maintaining the die at a temperature below 40*F, ejecting the block from the mould when the block has cooled sufficiently to form a rigid skin and further cooling the ejected block in a bath of cold water. |