| 摘要 |
This method forms novel plastic sleeves which are easily ejected from their moulds. They may be screwed together and detached, forming esp. the rear section and front barrel grip (1) of a writing instrument, e.g. a pen or propelling pencil. They may also be used in the top cap and barrel construction, of e.g. a ball point pen. The threads are moulded-on, running axially along a slowly-tapering conical area of the sleeve. They are periodic projections, segments or points. Corresponding periodic thread elements are moulded inside an internal conical area of the mating sleeve section. Also claimed are (i) the mould used which has a negative contour with the appropriate internal or external thread. Along the decreasing taper of the thread, at any location, the next but one thread projection is approximately at the same radius as the thread valley at the location, in respect of the mould or moulding produced. Mould and moulding thread projections and depressions, run at the same angle ( alpha 2); and (ii) the sleeve moulding which has a fast-coupling thread as described, and is used in a writing instrument, such as a ball point pen, propelling pencil or fountain pen. The sleeve has bayonet thread elements (projections, segments or points) spaced around the circumference and along the axial direction. The threads are displaced radially, with constant offset, along a conical surface. |
