Oy Kwh Pipe Ab

Anders Andtbacka

Gunnar Blomqvist

Stefan Slotte

A method for preparing an end of a thermoplastics tube ( ) is provided, wherein the tube is manufactured by spirally winding and welding together of a hollow profile ( ) having a substantially rectangular cross section. The method includes the following steps: cutting the end of the tube by a planar transversal section; extruding a second hollow profile ( ) having a rectangular cross section and an outer shape essentially similar to Fat of the hollow profile ( ) from which the tube ( ) is manufactured; spirally winding the extruded second hollow profile ( ) around a drum having a diameter corresponding to inner diameter of the tube ( ); cutting a loop ( ) from the second hollow profile ( ) in a length corresponding to circumference of the tube end; joining the ends of the loop ( ) to each other, whereby a ring ( ) is formed having the same inner and outer diameters as the spirally wound tube ( ); placing the ring ( ) against the cut tube end; and welding the ring ( ) to the tube end.

Preparation of an end of a thermoplastics tube manufactured by spirally winding a hollow profile

A method for joining thermoplastic pipes made by spiral winding a hollow profile with mainly rectangular cross section. The method includes: cutting an end of the pipe along an inside of a profile side wall fastened to a nearest preceding wound round of said profile and with a section cutting an outermost end of the profile in a right or obtuse angle, or equal size for all pipe ends to be joined together; closing hole in such cut profile ends, and preparing end surfaces of the pipes along their entire peripheries; positioning two pipes in alignment with each other; inserting a welding ring, having dimensions matching with the inner and outer diameters of the pipes, between the two pipes; the welding ring comprising at least one loop of a resistance wire covered by a thermoplastic sleeve, aligning the two pipes with an inner root support and an outer root support, pressing the pipe ends together against each other; connecting the resistance wire of the welding ring to a current source to heat the thermoplastic materials in the welding ring and in the pipe ends so that the thermoplastic materials melt and form a welding seam, cooling the welding seam; removing the root supports and other accessories from the pipe welded together, and cutting off the connecting wires of the welding ring.

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Vasa, Finland

Anders Andtbacka