| 摘要 |
<p>Plastic barrel has injection moulded upper and lower parts, each of which are reinforced at their ends so as to have a wall with a triple to quadruple thickness, these parts being united by toothed flanges around the periphery of each part. The faces of the teeth make an obtuse angle with a perpendicular directed towards the base of the part to which the teeth do not belong, and each of the parts has, before the first tooth and after the last, has a thrust face supporting the compression force, the ends of the barrel parts forming a smooth flange outside the barrel after assembly, and the internal face of the upper part forming a smooth surface with the internal face of the lower part. Each barrel part also has, at a distance from the flange about one quarter the total height of the barrel, a rolling ring whose external limit is inscribed with the external limit of the flange in the same cylindrical envelope. The barrel parts are easily united to form a liq. tight seal without welding.</p> |
