| 摘要 |
618,536. Extrusion apparatus. B. X. PLASTICS, Ltd., and NICHOLAS, D. C. July 30, 1946, No. 22728. [Class 87 (ii)] In apparatus for the extrusion of screw-threaded tubes or coils of plastic material, rubber, or rubber like material, a feed screw 2 is attached to or made integral with a mandrel 12 protruding up to or beyond the extrusion orifice of a die 5, a helical thread being provided either on the internal surface of the die or on the mandrel. The die which, as shown, has a screw-threaded bore 9 is held in an annular mounting 4 by means of four adjusting screws 6 and a lock nut 7. The die can be adjusted to vary the width of the annular feed passage 14 whereby the amount of plastic fed to it is controlled. Roughening of the internal surface of the die 5 lessens slip of the plastic material as it passes through the screw-threaded bore 9 so that the resultant tube will have an external screw-thread on it. If the diameter of the mandrel is made approximately equal to the minimum diameter of the screw-thread a coil will be extruded. For the production of internally threaded tubes the mandrel 12 instead of the die is given a screw thread. Wire or other metal reinforcement to be embodied in or wound upon the tubes or coils may be fed forward through the stationary or rotary parts of the die, and the die member 5 may contain one or more extra conduits through which threads, strips or tubes, which are not rotated, may be extruded on to the coils etc. to produce decorative effects.
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