FORFARANDE FOR FRAMSTELLNING AV DUBBELVEGGIGA PLASTROR MED RINGFORMIGA KORRUGERAD YTTERVEGG OCH SLET INNERVEGG

• Main Authors: R P HEGLER, W HEGLER
• Format: Patent
• Language: Swedish
• Published: 29.03.1982
• Subjects: AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING; BLASTING; CUTTING; CUTTING-OUT; ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVEFUNCTIONING OF MACHINES OR INSTALLATIONS; HAND CUTTING TOOLS; HEATING; JOINTS OR FITTINGS FOR PIPES; LIGHTING; MAKING GRANULES OR PREFORMS; MEANS FOR THERMAL INSULATION IN GENERAL; MECHANICAL ENGINEERING; PERFORATING; PERFORMING OPERATIONS; PIPES; PREPARATION OR PRETREATMENT OF THE MATERIAL TO BESHAPED; PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCESIN A PLASTIC STATE; PUNCHING; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIALCONTAINING PLASTICS; SEVERING; SEVERING BY MEANS OTHER THAN CUTTING; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDEDFOR; SHAPING OR JOINING OF PLASTICS; STAMPING-OUT; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; THERMAL INSULATION IN GENERAL; TRANSPORTING; WEAPONS; WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE, IN GENERAL

In the manufacture of double-wall plastic tubing in which the outer wall has transverse corrugations and the inner wall is smooth, in the case of annular transverse corrugations the air pressure between the two walls cannot be balanced with the external air pressure, resulting in deformations of the inner tube. To permit an equilibrium of pressure before the inner wall hardens, openings are pierced in the outer wall or openings are produced between the two walls for communication between the inner chambers of the transverse corrugations. After the hardening of the inner tube, these openings are reclosed by fusion.