WRITING INSTRUMENTS

摘要

1424122 Extruding rods for writing implements GILLETTE CO 11 Jan 1973 [24 Jan 1972] 1624/73 Heading B5A [Also in Division B6] An extruded circular rod, which may comprise specified thermoplastics, for use as points in writing implements and comprising an axial channel and radial channels connected thereto, is made by extruding the rod from a die 24, Fig. 4, around a mandrel, Fig. 6, defining the channels and having bores 68 for the passage of channel supporting air, followed by initially stretching the rod in passage through a quenching bath 32 and then, after passage through a drier 70, reheating the rod during passage through a heater 36, to a temperature of 25‹ to 130‹ F. below the melting point of the thermoplastics, at which it is subjected to compressing and further stretching forces in being drawn through a sizing die 72, followed by passage through a further quenching zone 37, and a drier 701. Internal stress in the rod may then be stabilized, Fig. 5 (not shown), by drawing under tension through a heating zone at between 10‹ to 100‹ F. below the melting point of the thermoplastics, means 83 being provided for forming the writing tip. The cross-sectional area of the rod does not exceed 32,000 square mils, and that of the channels is less than 4 % that of the rod. The initial stretching is to a cross-sectional area not more than a quarter of that of the die, the diameter ratios of the die and initially stretched rod being 2 : 1 to 5 : 1, and preferably 3 : 1 to 4 : 1, and the initially quenched diameter is not more than 3 to 20%, and preferably 4 to 10%, larger than the final desired diameter. A writing tip made from the rod may be employed in a writing instrument Fig. 1 (not shown), or in the Fig. 2 modification (not shown) where the upstream end of the tip comprises a blunt end abutting a small sponge or porous member acting as an intermediate reservoir between the main ink reservoir and the tip. Preferred dimensions of the channels are specified.