A tapered synthetic resin pipe can be produced by winding belt-like or thread-like glass fiber around a tapered core bar, inserting it into a tapered mold and thereafter pulling out only the core bar, pouring a thermosetting synthetic resin in liquid form into the mold, inclining the mold by a predetermined...http://www.google.ca/patents/US4002714?utm_source=gb-gplus-sharePatent US4002714 - Method for producing a tapered pipe of reinforced synthetic resin
