Abstract:
The invention concerns a method for fabricating a concrete slab in a substantially horizontal slip casting process, in which method concrete mix is fed into a mold through a delimited cross section moving progressively in the casting process so as to form a concrete product of a desired shape, characterized in that onto the surface of the casting bed (1) is placed a core (3, 9, 10, 11) capable of delimiting the cross section of the concrete product (5, 5null) so as to provide an opening or a provision for an opening in the bottom surface of the slab. The invention also concerns a core for obtaining an opening or a provision for an opening characterized in that the structure and/or material of the core is/are such that the core is capable of yielding in vertical direction. A core according to the invention may also be a multipart core, the outer part of which becomes detached from the inner part of the core in conjunction with lifting off the concrete slab from the casting bed.
Abstract:
The invention relates to a method for the manufacture of well equipment with permanently mounted ladder steps, and wherein the method uses mould parts for forming a mould cavity, which mould parts comprise mould elements that will, following discharge of the cast well equipment, leave a number of mounting apertures in the well equipment, which mounting apertures are located in such a manner that the anchoring parts of the ladder steps can be driven thereinto. The invention also relates to an apparatus for exercising the method, wherein the apparatus comprises a frame with a first arm on which a number of ladder-step grippers are configured, each of which being configured for receiving and securing at least one ladder step. The frame of the apparatus also comprises holder-on means that extend opposite the ladder-step grippers, and the apparatus comprises means for forming a substantially continuous and uninterrupted reduction of the distance between the ladder-step grippers and the holder-on means, and means for discountinuing this displacement at a predetermined distance between the ladder-step grippers and the holder-on means.
Abstract:
A collapsible corner assembly is used in a collapsible form assembly to form a hollow structure, such as a four or five sided hollow concrete structure. One embodiment of the form assembly includes two collapsible corner assemblies, two fixed corner assemblies, and intermediate panels coupled to the corner assemblies. Each collapsible corner assembly preferably includes collapsible side portions and retractable members forming outer corner forming surfaces. To collapse the collapsible corner assembly, the retractable members are retracted and the collapsible side portions are moved inwardly. Collapsing the collapsible corner assemblies allows the form assembly to be removed from the hollow structure.
Abstract:
A method is shown for manufacturing a polyethylene jacket of the type used in pre-insulated piping systems. A mandrel is first coated with a brittle polymeric coating. A melt profile of polyethylene is then extruded onto the mandrel and spirally wound to produce adjacent windings. The adjacent windings make contact to form a finished jacket which is in engagement with the brittle coating. After the jacket has set, an external compressive force is applied to the tubular member thus formed sufficient to crush the internal brittle coating, thereby freeing the polyethylene jacket from engagement with the mandrel. The jacket can then be removed from the mandrel.