| 摘要 |
770,705. Pug-mills. UNITED STATES RUBBER CO. Jan. 28, 1955 [April 2, 1954], No. 2617/55. Class 86 [Also in Group V] An extruder comprises a multi-flight feed screw 23, Figs. 1 and 2, and a yieldable plunger 21 slidably mounted in a housing 34 in which is located the receiving end 22 of the screw. The plastic material to be extruded is fed in strip form 12 through a slot 24 in the plunger, and when a bank of the material accumulates between the lower end of the plunger and the receiving end of the screw the plunger rises against the resistance of springs 32. The bank is re-fed into the screw by downward movement of the plunger, this downward movement being limited by a plate 38. The plunger and its guides 62 are made of a material, e.g. polytetrafluorethylene, which will not stick to the plastic material. The screw has one flight 39 at its receiving end (up to a point 40), and two flights 39, 41 from the point 40 to its discharge end. In modifications the material may be fed in strip or pellet form not through the plunger but through a passageway at one side thereof. The invention is described in connection with a cross-head extruder for coating an electrical conductor with plastic material.
|
