| 摘要 |
870,669. Hypodermic syringes. EVERETT & CO. Ltd., S., and R. J. Dec. 8, 1959 [Dec. 16, 1958], No. 40573/58. Class 81 (2). A unitary piston and piston rod for an hypodermic syringe is moulded from synthetic plastic, e.g. polythene, and has an internal bore 6 open at the rear end and a piston 4 which has two or more spaced annular ridges 11, 12 and is slightly larger in diameter than the rod 5, there being a neck 7 of reduced diameter between the piston and the piston rod. Two annular ridges may be provided, each ridge having a face 13, 16 perpendicular to the piston axis and a face 14, 15 which slopes at an angle to the piston axis, the perpendicular faces being on opposite sides of the ridges. The piston is made over-size and is sized by placing in a forming tube, or a glass or acrylic resin syringe barrel of slightly smaller diameter, and heating at 40‹ C. until its diameter conforms to that of the tube or barrel. |
