A single-piece injection-moulded rack and a mould for its manufacture

A singie-piece injection-moulded rack (10) for holding test tubes or similar articles comprises, in a preferred three-tiered form, an intermediate tier (14) in the form of a lattice defined by the intersection of two superposed sets of parallel bars(15,17). In a mould (40, 42) for producing the rack (10), the two sets of bars are formed by two pairs of correspondingly- channelled slides (31, 43; 60, 70) which cooperatively engage to form a portion of the mould cavity corresponding to the lattice. The channels (35, 47; 62, 72) in each set of slides are aligned with the path of movement of the slides to permit sliding uniaxial movement relative to the moulded bars (15, 17). To further enable this sliding movement between the mould segments (40, 42) and the moulded rack (10) to occur, connecting supports (20) between the top tier (12) and the intermediate tier (14) are provided on the sides of the rack, while connecting supports (21) between the intermediate tier (14) and the bottom tier (16) are provided on the front and rear of the rack. With this arrangement, the slides (31,43; 60, 70) which form the lattice of the intermediate tier (14) are free to slide, as well, along the inner surfaces of the supports (20,21), which they also help to form.