GB1254090A - Rotational moulding - Google Patents

Abstract

1,254,090. Rotational moulding. MITSUBISHI PETROCHEMICAL CO. Ltd. 3 April, 1970 [4 April, 1969], No. 15986/70. Heading B5A. Apparatus for moulding thermoplastic resin articles comprises a plurality of moulds 4 mounted on and rotatable about axes 43a, 43b which are supported by circular supporting plates 40, 41, such that these plates may be rotatably supported by shafts 23, 24 in a rotary frame 5 rotatable about axes 7 and 8. Hence each mould is rotatable about three axes, two of which are parallel, as shown. Plate 41 is pivotable on fixed shaft 24 and plate 40 is fixed to rotatable shaft 23, shafts 23 and 24 being joined by a free joint 38. Shaft 23 is driven by means of a chain 13 acting through a shaft 11, another chain, and shaft 15. Planet gears 44a, 44b co-operating with a gear fixed on shaft 24, cause the moulds to rotate about their axes 43a, 43b. Chain 10 and sprocket 9 drive the frame 5 to rotate it on axes 7 and 8. Shafts 23 and 24 are removably supported in recesses 27, 28 by movable bearing hooks 25, 26 rotatable by motors 31, 32 to release or secure shafts 23, 24. Dollies 6 on tracks 7 are provided for removing the moulds from the frame 5. The dolly includes an elevator frame 59 having bearing rods 70 on which the shafts 23, 24 may be supported. A motor 54 drives rolls 55a, 55b, 56a, 56b which wind up cables 58a, 58b, 57a, 57b to lower or raise the frame 59 to a position at which the moulds can be transferred between the dolly 6 and frame 5. Bearing rolls 62a, 62b, 63a, 63b are driven by a motor 64 to interact with plates 40, 41 and thus maintain rotation of the moulds about shafts 23, 24 after removal of the moulds from the frame 5. Heating elements 45 provide jet flames through apertures 46, to heat the rotating moulds from a fuel supply pipe entering through rotary shaft 8. In another embodiment (Fig. 6, not shown), the support (2) is provided upright on a dolly (22) instead of the floor, and the apparatus can be located in a heating chamber. The moulds may be cooled by a cooling medium applied to the rotating moulds. Materials which may be moulded include powders or granules of polyolefins such as polyethylene or polypropylene.