Two-shell retractable casing for paper knife - has shells in two-member pin-joined arms and reuniting to form handle when retracted

摘要

The retractable casing may be used on a paper-knife. It encases the blade (2) when in a first position, and forms the handle of the knife when retracted. Two-member pin-jointed arms (4a, 7 and 4b, 8) constitute the retraction mechanism. Two such members are used, disposed symmetrically about the longitudinal axis of the blade (2), and each incorporating a half-casing (4a, 4b) element as a member. The casings (4a, 4b) are similar 'U' sections each pinned to a cursor (3) which slides along the blade (2). The rear ends of the casings are pinned to one end of a link bar (7, 8) of which the other end is pinned to the heel (2a) of the blade. The cursor (3) may also serve as a handguard, and the casings (4a, 4b) may also include a retractable strap (14). The links (7, 8) form an axial extension of the casings (4a, 4b) when they cover the blade (2), and fit in the casings when they form the handle.