| 摘要 |
930,323. Non-metallic pipes. FARBWERKE HOECHST A.G. July 6, 1959, No. 23208/59. Class 99(2). [Also in Group V] A process of strengthening pipes of, or containing, polyvinylchloride comprises conducting the extruded pipe 1 through a heating bath 4, subjecting the pipe to internal pressure to expand it hemispherically against the outlet wall 5 of the bath, the pipe during expansion being at a temperature of from 50‹C. to 130‹C., and withdrawing the pipe through a cooled sizing conduit 6. |
