Void rectification in layered composite structures, particularly marine structures, involves dispensing of polyurethane via openings in outer metal layers into a void in a central polyurethane layer

摘要

Voids are located in a central polymer layer(ii), usually 10-100mm thick polyurethane, sandwiched between two metal plates(i,iii), 2-20mm thick. A mixture comprising initial components of the reactive polymer is introduced by a dispenser into a void via one or more openings(iv) in one or both outer metal plates. Trapped air is driven out via an additional opening(v) in the plates. Openings for filling the voids are bored one or both metal plates(i,iii). The dispenser comprises a cylinder(xi) with base(xiii) and material outlet, a cover plate(xii) and piston on a piston rod(xv). The cover and base are detachable using quick release connectors on the cylinder and the piston is connected to the piston rod via a ball joint. For material delivery to voids to be filled the piston rod rotates in a thread in the cover plate and moves the piston towards the material outlet. A hose connection linking the dispenser and the opening in the metal plate includes a valve. In use the base and cylinder are assembled and the cylinder filled with the mixture components. The piston is then inserted into the cylinder and the latter closed by the cover plate. Mixture is then dispensed via the outlet in the base. When empty the dispenser is dismantled and cleaned. An independent claim is included for the dispenser whose working volume between base, cylinder and piston is not >10000cu cm.