FR2670154A1 - Method for the production of tubular flexible elements made of strong fibres bonded by synthetic resin and arranged around a heat-shrinkable inflatable flexible jacket - Google Patents

Abstract

The invention relates to a method which allows the production of a tubular and conical flexible element intended to be moulded, according to which method a flexible and leaktight skin (casing) is formed by slipping a sleeve (2) made from a heat-shrinkable product over a mandrel (1) driven in rotation, the said sleeve, being heated, adopting the shape of the mandrel. Rovings of strong fibres (3) impregnated with curable synthetic resin will then be wound over the sleeve. The skin covered with the interlacing of rovings will then be separated from the mandrel. The invention applies in particular to the production of sports articles, such as a golf club handle, bicycle fork, fishing rod elements or components of various shapes, such as preforms for jet-engine turbine blades made of ceramic fibres.

Description

The present invention relates to an improvement made to the subject of French patent application no. 90 10 108 of August 8, 1990 by the same applicant, which relates to the production of a flexible tubular element intended to be molded, according to which coils are wound. strands of resistant fibers impregnated with synthetic resin curable around an inflatable flexible hose, which is characterized in that the flexible hose is threaded on a rigid mandrel mechanically assisted in rotation, and in that the strands of fibers are wound resistant on the hose before separating from the mandrel the tubular flexible element thus obtained.

According to the present invention, the inflatable flexible hose is produced by threading on the mandrel a heat-shrinkable sheath which, once heated, will remain sealed by taking the shape of the mandrel.

The inflatable flexible hose thus obtained may have the shape of a mandrel other than cylindrical, for example conical, which makes it possible for example to produce a golf club handle, a fishing rod element, a conical windsurf mast or pieces of various shapes such as blanks of ceramic fiber turbine turbine fins.

To clearly understand the device according to the invention, there will be briefly described below an example of execution without limitation, with reference to the accompanying drawing, the single figure of which shows a conical mandrel (1) on which a sheath has been threaded ( 2) of a flexible heat-shrinkable material which having been heated to its shrinking temperature by the passage of a current of hot air will have adopted the shape of the conical mandrel.

Wicks of fibers (3) impregnated with curable synthetic resin are then wound around the sheath (2). It is advantageously possible to use a sheath in crosslinked polyolefin of the family of polyethylenes whose shrinking ratio is commonly 2 to 1 when brought to 900 C but which from 1300 C to 2500 C regains its elasticity necessary during inflation and of the polymerization of the coating resins coating the locks (3) of fibers. In the case where ceramic fibers are used coated in resins polymerizing at high temperatures, polytetrafluoroethylene sheaths whose shrinking temperature reaches 3270 C could be used to regain their elasticity at significantly higher temperatures (520 C).

 To facilitate undressing of the composite envelope of the hollow mandrel (1), it is advantageously possible to introduce pressurized air which will come to peel off the envelope while coming out through the holes (a).

Claims (1)

CLAIM 1) Method for producing a flexible tubular element intended to be molded according to which strands of resistant fibers (3) impregnated with curable synthetic resin are wound around an inflatable flexible hose, characterized in that said hose is produced flexible inflatable (2) by introducing on a rigid mandrel (1) driven in rotation, a sheath made of a flexible heat-shrinkable product and that said sheath is heated so that it comes, by shrinking, adopt the shape of the mandrel rigid (1).