| 摘要 |
PROBLEM TO BE SOLVED: To prevent an excess carriage of material resin and to conduct stable carriage by a method wherein at least the middle part of an inner wall surface of an internal hollow chamber of a barrel between a supply port and a delivery port is finished to be specular. SOLUTION: A right-cone-shaped internal hollow chamber is is formed in a barrel 1 and an injection cylinder 2 is fixed at a delivery port 1o in the fore end thereof, while a supply port 3 is formed in a part 1b on the rear end side of the internal hollow chamber is. At least the middle part M of an inner wall surface 1w of the barrel 1 between the supply port 3 and the delivery port 1o is finished to be specular. In other words, the inner wall surface 1w corresponding to a part except three to four turns of a helical projecting thread 7 in the fore and rear ends of a screw 6 is buffed so that central-line average roughness = 8μm of below be obtained preferably. The degree of the specular finish is set according to the kind of a resin material to be used. In the middle part M, consequently, the coefficientμof friction becomes small, the speed of carriage of the material becomes low relatively and thus excessive carriage is prevented.
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