| 摘要 |
A method for injection moulding a tie (14) comprises: (a) providing a mould that includes parts (10, 12) for defining a cavity in the shape of the tie; (b) injecting molten plastic material into the mould cavity; (c) solidifying the plastic material to form the tie; (d) separating the mould parts (10, 12) to enable removal of the tie (14) from the mould; and (e) removing the tie from the mould. The mould defines a tie (14) in which an abutment wall (12) includes bulges (30, 32) adjacent each of opposite ends of the abutment wall for holding the abutment wall (12) in respective mould parts (10, 12) when they are first separated. The bulge (30) adjacent one end of the abutment wall is defined by a first mould part (10) and the bulge (32) adjacent the opposite end of the abutment wall is defined by a second mould part (12). As the mould parts (10, 12) are being separated, the bulges (30, 32) initially hold the abutment wall (12) in the mould parts (10, 12) and cause stretching and thickness reduction of the abutment wall (12) so that the tie (14) can be removed from the mould. Each tie (14) comprises an elongated tongue with two ends and two broad sides, a locking head at one end of the tongue, a first set of ratchet teeth extending along one broad side of the tongue and a second set extending along the other broad side of the tongue. The locking head has sides, defining an opening for receiving the tip of the tongue, which include a movable pawl (18) that is hinged at one side of the opening and the abutment wall (12) that is across the opening from the pawl (18). The pawl (18) has at least one pawl tooth (24) for engaging with the first set of ratchet teeth when the tongue has been inserted through the opening with the first set of ratchet teeth facing the pawl. The pawl (18), when the pawl tooth (24) or teeth are engaged, is movable towards an abutment surface (20) of the abutment wall (12) in response to pressure applied to the tongue in a direction opposite to the direction of the insertion in order to force the second set of ratchet teeth against the abutment surface (20). The abutment surface (20) includes at least one tooth (22) for locking engagement with the second set of ratchet teeth when the tongue has been inserted through the opening with the second set of ratchet teeth facing the abutment surface (20) and the side of the tongue including the second set of ratchet teeth is forced against the abutment surface (20) by movement of the pawl (10).
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