Societe Anonyme Diamant Boart

Wavin B.v.

Pieter Kramer

Honore J Lambot

Johannes H Fliervoet

Maria J Fliervoet

The invention relates to a process for manufacturing an inner tube element made of synthetic resin for a double tube coring apparatus provided for deep boring. The tube element is provided with coupling nipples for connecting it to other inner tube elements. Fibers coated with synthetic resin are wound helically onto a cylindrical mandrel so as to overlap each nipple. This process gives the tube element a higher strength than that of glued nipples.

Process for manufacturing the inner tube element for a double tube

An inner tube element for a coring apparatus comprising a double tube, made of synthetic resin reinforced with fibers and provided at its ends with connecting nipples, is entirely made of synthetic resin and overlaps, at each of its ends, a part of the nipples having a rough surface gripped by said fibers, preferably in the form of webs of glass fibers. The inner tube element is manufactured by a process in which two nipples or couplings are placed onto a cylindrical mandrel having a constant section and rotating about its longitudinal axis, at a predetermined distance corresponding to the tube element to be manufactured, a part of said nipples having an inner diameter substantially identical to the diameter of the mandrel and having a rough surface, and fibers coated with a synthetic resin are wound helically onto said cylindrical mandrel, so as to overlap the rough part of said nipples.

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Hardenberg, Netherlands

Pieter Kramer