GB753029A - Improvements in or relating to processes and apparatus for the manufacture of tubes from hardening substances, such as concrete and the like - Google Patents

Abstract

753,029. Concrete, fibre cement &c. tubes. MANNESMANN AKT.-GES. Feb. 12, 1954 [Feb. 12, 1953 ; Dec. 23, 1953], No. 4247/54. Class 99(2). In the manufacture of tubes from hardening substances for example concrete fibre-cement mixtures and the like the batch of wet material required for the manufacture of a tube is supplied to a core roller in the form of a flat continuous length corresponding to the length of the tube by means of a conveyer belt guided by tensioning and guide rollers and is applied to the core roller with one or more rotations of the latter and after application to the core roller has been completed the material on the roller is compacted in the course of a few more rotations by gradual adjustment of a pressure roller towards the core roller and is thereby brought to the wall thickness of the finished tube and while the material is being applied to the roller and compacted the tube is maintained below atmospheric pressure by using an evacuated core roller. The apparatus employed comprises a porous conveyer belt a core roller permeable to air and liquid a pressure roller arranged below the core roller and a tensioning roller arranged above the core roller and adapted to be swung out of its tensioning position in a direction normal to its axis advantageously into a plane which is disposed below the plane of the conveyer belt in the region where it enters the gap between the pressure roller and the core roller. A porous conveyer belt 1 comprises a driving roller 2 and main tensioning roller 3. Above theÀcore roller 5 is tensioning roller 7. The force of a pressure roller 6 is adjustable. This roller is operated by a pressure cylinder 8. While the pipe material is being compacted the interior of the core roller 5, which roller is permeable to air and water, is kept below atmospheric pressure. The tensioning roller 7 is moved to permit removal of the tube. An auxiliary tension roller 11 maintains the tension of the belt. To prevent belt slip the drive roller 2 may be uncoupled from its drive means. The roller 2 may be driven by a motor through an infinitely variable gear 14 and clutch 16. The clutch may be an overrunning clutch or an engageable or disengageable clutch, for example a magnetic clutch. The shifting movement of the clutch may be derived automatically from rocking movements of the tensioning rollers. Limiting rings 18, 19 may be provided at the ends of the roller 5, Fig. 3. The core roller may be perforated and covered with a thin water pervious fabric or may consist of porous ceramic masses or of fretted glass or of other sintered masses. The tubes may consist of two or more layers. The individual layers may consist of different mixtures or mixtures of substances having different proportions or properties.