Oy Kwh Pipe Ab

Stefan Slotte

Gunnar Blomqvist

Anders Andtbacka

Jonas Holmlund

Charlotta Risku

Mikael Finne

Charlotta Leppaenen

The invention concerns a method for manufacturing pipes coated with a peelable protection layer, wherein the core pipe () is produced by extruding and calibrating, after which the surface of core pipe () is heated before a protecting coating layer () is applied onto the core pipe () on passing through a coating die (), followed by cooling the applied coating layer () before the readily coated pipe () is drawn out of the process. The method is characterized in that the degree of adhesion between core pipe () and coating layer () is controlled by rapid and effective heating of the surface of the core pipe () to a predetermined temperature and by controlling welding time and stretching of the coating layer being applied onto the core pipe () by maintaining a controlled vacuum level inside the coating die () forcing the coating layer to hit the surface of the core pipe at an angle as steep as possibly, preferably between 45 and 90 degrees, most preferably between 60 and 80 degrees.

Method for manufacturing coated pipes

The invention relates to a method and a device for cooling an extruded thermoplastics pipe () by directing a gaseous cooling medium tangentially towards the inner surface of the thermoplastics pipe () along its whole periphery, whereby the interior of the thermoplastics pipe () is divided by means of a protecting pipe () into an outer ring-shaped flow channel () for the cooling medium along the inner surface of the thermoplastics pipe (), and a central return channel () through which a part of the cooling medium is intended to be sucked back influenced by the flow of cooling medium in the outer ring-shaped flow channel (), and to be redirected towards the inner surface of the thermoplastics pipe (). The invention is characterized in that the cooling medium is air, and that there is a cooling equipment () mounted in the return channel (), whereby temperature and flow rate at least of the cooling water led to the cooling equipment () and possibly also of the cooling air which is fed into the thermoplastics pipe () are adjusted and controlled based on dimension and extrusion rate of the thermoplastics pipe () being manufactured.

Device for internal cooling of extruded thermoplastics pipes

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

Stefan Slotte