| 摘要 |
703,948. Extruding plastic material. UNITED STATES RUBBER CO. Oct. 31, 1951 [Feb. 17, 1951], No. 25427/51. [Class 87 (2) The material is heated by a rotating plug 24 in frictional engagement with the stream of plastic material. This plug may rotate at 150-1,000 r.p.m. and may increase the temperature of the material by 50‹-250‹F. in less than one second. To prevent the plug scorching the material the plug is cooled, as by oil at 100‹- 150‹ F., the oil being circulated through pipes 36, 37 and a sleeve 26 which is separated from the rear of the plug by a bearing washer 27. The plug is carried by a shaft 25 disposed within sleeve 26 and is rotated by pulley and belt 33, 34. The sleeve forms part of a cap 28 screwed on an extension 29 of the extrusion crosshead 20: The material 11, e.g. vulcanizable rubber stock, is impelled by a screw 13 and is initially heated to 200‹-250‹ F. by steam &c. in chambers 18. The material passes the plug, by which it is further heated, enters a preliminary shaping die 16 (where paraffin oil lubricant is applied to its surface through pipe 41, duct 39 and slit 38) and passes through a long vulcanizing die 17 which is heated by its resistance to electric current supplied through terminals 46, 47. The die is insulated at 48. A constriction 49 in the die develops back pressure. A bleed passage 51 is provided. |
