Abstract: A socket of a thermoplastic pipe is provided with an internal groove by subjecting the tube to an upsetting action and simultaneously inflating the tube by an inner pressure. Subsequently a moulding ring is expanded and the tube is shrunk onto the expanded ring by cooling. Before shrinkage the inner diameter of the bottom of the groove is at least equal and preferably greater than the outer diameter of the moulding ring in expanded form.

Abstract: A hydrostatic extrusion apparatus whereby thermoplastic polymers can be hydrostatically extruded in a solid state is described. The apparatus includes:(a) an outer casing or tooling support means,(b) a container assembly concentrically contained within the outer casing and having pressure means attached thereto to provide extrusion pressure to a fluid in the assembly, sealing means to prevent leakage of the fluid, means for holding a polymer billet and including a die portion, and(c) a receiver assembly axially aligned with the container assembly concentrically within the outer casing having pressure means to clamp the container and receiver assemblies together, a mandrel for holding and aligning a mandrel-head in spaced relationship with the die, and means for receiving, lubricating and cooling the extrudate.Optionally, means for preheating and loading the polymers into the container assembly are provided whereby the press may be operated on a semi-continuous or continuous basis.

Abstract: The internal core of a molding apparatus does not have to be axially moved for molding a plastic pipe provided with a peripheral groove therein. This is accomplished by providing the internal core with a groove of such narrow width as to always be open to the surrounding cooperating mold body while at the same time preventing plastic material from entering the groove as the plastic material is being introduced into the mold cavity.

Abstract: A method and apparatus for causing a flexible tubular lining material to be fixed to the inner surface of a pipe line wherein the tubular lining material is initially attached to the inner surface of the pipe line by a binder provided on the surface of the tubular lining material which comprises providing a flexible hose material having a porous structure inside the pipe line which has been lined with the tubular lining material and introducing a heated gaseous fluid stream into the interior of the flexible hose whereby the heated gaseous fluid stream is introduced through the pores of the flexible hose along the inner surface of the lined pipe line, the flexible tubular lining material being warmed to accelerate the curing of the binder interposed between the inner surface of the pipe line and the flexible lining material.

Abstract: A mould for use in the manufacture of thermoplastics eg PVC pipe by radial expansion of a pipe blank, the mould comprising a cylindrical central portion 10 and two removable mould end portions 11, 12. The pipe blank 14 is located centrally within the mould by mandrels 13 within each mould end portion 11, 12. Water inlet/outlet ports 15, 16 are provided in each mould end portion 11, 12 to admit water to and remove it from the region between the blank 14 and the mould walls, and the mandrels 13 are hollow to permit inlet/outlet of water through the interior of the blank 14.

Abstract: A method of manufacturing thermoplastics pipe by the radial expansion of a pipe blank within a mould. The blank 28 is inserted horizontally into a raised central mould portion 12, with the ends of the blank 28 extending outwardly of the ends of the central mould portion 12. Portion 12 is then lowered to a first position where mandrels 19, 20 enter the blank 28 from each end, and then a second position where mould end caps 15, 17 are closed onto the central mould portion 12, and heating and expansion of the blank 28 is then effected.

Abstract: Apparatus for use in the manufacture of socketed thermoplastics pipe by the radial expansion of a pipe blank. The apparatus includes an open-ended central mould portion 12 which can be raised or lowered on stanchions 10, 11 to three predetermined positions; a pair of mould end portions 15, 17 each having a supporting mandrel 19, 20 engageable with the pipe blank 28, end portions 15, 17 being advanceable to and retractable from the central mould portion 12. One of the mould end portions 15 is internally contoured to provide part of the socket-forming portion of the mould. The mould end portions 15, 17 can be held in an intermediate position, partially advanced towards the central portion 12 to locate the blank 28 on mandrels 19, 20 before closing of the mould.

Abstract: This invention discloses an improved method of producing fiber glass or fiber graphite reinforced racket frames in which a shell made of a plurality of layers of resin-impregnated oriented graphite fibers is squeezed during the heating period to contact completely with the inner surface of a mold cavity by means of two interior pressure separately generated by compressed air and a foamable elastomer or rubber composition wrapped within the shell.

Abstract: A method for manufacturing retortable cans is taught which includes the step of cable extruding a tube of plastic. Subsequently, a substantially gas-tight material is laminated to the outside of the tube and a plastic layer is laminated to the layer of substantially gas-tight material. Preferably, the gas-tight material comprises a metallic foil.

Abstract: A method of applying a vermicular expanded graphite composite material to the interior surface of a conduit by a two-step in situ compression process is disclosed.

Abstract: A method of producing a curved sausage casing by treating a sausage casing before curving with caustic solution and neutralizing the casing while in the curved configuration.

Abstract: The solvent barrier property of pigmented, solid polymeric articles is improved by pretreating the pigment particles prior to incorporation into the solid polymeric material so as to remove trapped gas from the surface and interstices of the pigment particles. Specific techniques for accomplishing this result include heating the pigment particles to a temperature above about 50.degree. C., but below the calcination temperature, scrubbing the pigment particles with an inert gas and subjecting the pigment particles to a vacuum.

Abstract: The apparatus comprises a double walled mould interior divided into two halves, a heat exchange exterior hollow envelope and a pressure-exchange compartment within the envelope surrounding the adjacent abutting surfaces of the rims of the two mould halves, heat-exchanges and pressure-exchanges producing means to rotate the apparatus on two axes, means to introduce a protective gas into the mould to avoid combustion of vapors and optional means cooperating between the heat-exchange and pressure-exchange means in the heating and cooling phases.The method includes controls of pressure and heat-exchange steps during the heating and cooling stages to avoid formation of bubbles, deformities and combustions, particularly when transparent plastic materials difficult to mould are used.

Abstract: .Iadd.An improved extrusion method is provided to produce plastic tubes having at least one end thereof an increased wall thickness. The method includes the steps of continuously advancing plastic material through an extruder to form a cylinder, cooling the extruded cylinder as it passes from the extruder, periodically increasing the speed at which the plastic material is fed to the extruder relative to the speed at which the cylinder is drawn from the extruder to produce a section having an increased wall thickness and dividing the cylinder thus formed. .Iaddend.