CENTERING PIECE FOR TUBULAR ELEMENTS MADE OF TWO MATERIALS AND PROCESS FOR MANUFACTURING THE SAME

摘要

The invention relates to a centering piece for tubular elements, made of two materials and to a process for manufacturing the same. According to the invention, the centering piece consists of an internal piece (2, 2') made of a material of high mechanical performances and chemical stability and an external piece (3, 3') positioned onto the said internal piece (2, 2'), made of a second self-lubricating material of low friction coefficient, having lower mechanical performances and chemical stability in comparison with the first material. The process for manufacturing the centering piece, as claimed by the invention, consists, during a first stage, in injecting a first material to form an internal piece on a tubular element and injecting a second material on the so formed internal piece, where the clamping of the said internal piece onto the tubular element is adjusted by the clamping effect on the plastic around the tubular element and the said internal piece of the centering piece, resulting from the volumetric contraction of the cooling material, after the injection process, a plurality of closing devices (5) being located on the peripheral part of the internal piece (2, 2'), the said plurality of closing devices (5) being equally spaced both on the circumference and longitudinally, on the said peripheral part of the internal piece (2, 2'), adopting a substantially prismatic geometry.