Patent ID: 6322653
Filing Date: 2001-11-27
Classification: B29C,B29L,Y10S,Y10T

Abstract:
A method of joining thermoplastics pipes (1) made by spiral winding of a hollow profile (2) with mainly rectangular cross section, characterized by the following stages:cutting an end of the pipe to be joined along an inside of a profile side wall that is fastened to a nearest preceding wound round of said profile, and with a section (3) that is cutting an outermost end of the profile in a right or an obtuse angle (.alpha.), of equal size for all ends of the pipes to be joined together,closing holes in such cut profile ends (3), and preparing the end surfaces of the pipes (1) to be joined along their entire peripheries, to present an even surface,positioning the two pipes (1) in alignment with each other so that the cut profile ends (3) are axially offset,inserting a disc-formed welding ring (5), having dimensions matching with the inner and outer diameters of the pipes; between the two pipes (1) to be joined, which welding ring comprises at least one loop of a resistance wire (6) covered by a thermoplastics sleeve (7),centering the two pipes (1), with an inner root support (8) and an outer root support (9) around the welding ring (5) and adjacent pipe ends,pressing said pipe ends together against each other,connecting the resistance wire (6) of the welding ring to a current source (12) for heating the thermoplastics material in the welding ring (5) and the thermoplastics material in the adjacent pipe ends so that the thermoplastics materials melt and form a welding seam,cooling the welding seam,removing the root supports (8, 9) and other accessories (10, 11) from the pipe welded together, andcutting off connecting wires (13) of the welding ring.