摘要:
An elongated product is formed such that first a core is formed, the outer surface of the core being made of plastic. Thereafter, a tubular metal layer is extruded such that the layer is seamless. When the metal layer is extruded, a clearance (16) is allowed between the metal layer and the core. After the metal layer has cooled, the outer surface of the core is arranged against the inner surface of the metal layer An adhesive action is arranged between the core and the metal layer and a permanent compressive force is arranged, which compressive force compresses the core and the metal layer together
摘要:
A multilayer pipe which comprises at least an inner layer and an outer layer. The inner layer is made of extrudable plastic, such as polyethylene PE, cross-linked polyethylene PEX or polypropylene PP. The outer layer forms a fire-protecting layer and the matrix plastic of the outer layer is also made of extrudable plastic. A foaming agent, which does not react during the manufacture of the pipe, is mixed with the matrix. Further, the outer layer contains at least one additive in such a manner that the outer layer has a pipe-reinforcing component and a fire-retardant component. Most preferably, at least the outer layer is extruded by an extruder having a screw length ratio of less than 10 to its biggest diameter.
摘要:
The present invention relates to an apparatus for producing pipes of a moldable material, preferably plastic, comprising an extruder, a cylindrical mold comprising chill molds (4, 5), a mandrel (8) inside the extruder and a kernel (9) as an extension of the mandrel. The mandrel is attached at its front end to the extruder. The mandrel (8) and the kernel (9) can be kept concentric with the extruder and the mold if the mandrel and the kernel are joined to each other in such a manner that the angle between their center lines is adjustable.
摘要:
An elongated product is formed such that first a core is formed, the outer surface of the core being made of plastic. Thereafter, a tubular metal layer is extruded such that the layer is seamless. When the metal layer is extruded, a clearance is allowed between the metal layer and the core. After the metal layer has cooled, the diameter of the metal layer is reduced such that the metal layer contacts the plastic core. Thereafter, the metal is annealed such that the flexibility of the metal layer increases.
摘要:
A tubular product has a tubular base layer, a tubular innermost layer made of plastic by continuous extrusion, and a tubular tie layer of foamed plastic between and adhered to the base layer and the innermost layer. The tie layer is made of melt processable adhesion plastic, is extruded simultaneously with the innermost layer against the base layer, and has better adhesions to the base and innermost layers than the base and innermost layers have to each other.
摘要:
The invention relates to a method and apparatus for using recycled plastic material, and to a plastic product produced by an extruder. In the invention, crosslinked polyethylene is ground to powder form and mixed with e.g. polyethylene so that the proportion of the crosslinked polyethylene in the mixture is less than 30%. The mixture is supplied through an extruder (2) for making an extruded plastic product. In this way, crosslinked polyethylene can be recycled in a cost-effective and simple manner, while producing a plastic product that contains recycled crosslinked polyethylene.
摘要:
A branched pipe (5) is manufactured by continuous extrusion in such a manner that a manifold (5a) of a branched pipe (5) is manufactured by extruding plastic material into the space defined by moving chill moulds (1, 2) and a mandrel (10) arranged therein with an extruder (4). The manifold (5a) is provided with branch pipes (5b) simultaneously with the extrusion thereof.
摘要:
An apparatus for molding plastic including: (a) an injection space; (b) forming apparatus for supplying plastic material to the injection space, the forming apparatus having at least an inner conical stator and an outer conical stator and at least one rotatable rotor disposed outside of the inner conical stator; and (c) a piston for compressing the plastic material supplied to the injection space into a mold to form the plastic material into a shape determined by the mold.
摘要:
A method for manufacturing an extrudable product including the steps of (a) providing an apparatus including an extruder having at least one rotor with first grooves, at least one stator with second grooves and a clearance between the rotor and the stator, the first grooves, second grooves and clearance forming a processing cavity having a volume that is equal to the volumes of the first grooves, the second grooves and the clearance, the processing cavity having a cross-sectional area that decreases continuously along at least a part of an axis of the extruder, the extruder further having a supply for feeding a material to be extruded into the processing cavity; b) feeding the material to be extruded in a powder, pellet or granuate form into the processing cavity through the supply and causing rotation of the rotor relative to the stator such that the material is forced to proceed along an x-axis in a shear zone of the extruder where the material is subjected to a shear which causes a fictional heat that melts a part of the material and forms a bed of mainly unmelted particles and melt around the particles, the processing cavity being completely filled at a cross-sectional portion thereof that is a distance from the end of the extruder, the unmelted particles being present in the cross-sectional portion in an amount sufficient to increase a pressure in the extruder to a level that is higher than that needed for pushing the material further along the x-axis to a die.
摘要:
An extruder according to the invention comprises at least two annular conical feed gaps (9) one within the other, formed between a rotatable rotor (1) and a stator (4, 5). At lest some of the material to be extruded is subjected in the different feed gaps (9) of the extruder alternately to a higher pressure and then to a lower pressure. The rotor (1) or stator (4, 5) between the feed gaps (9) can then be balanced such that the pressure effect provides a hydrodynamic bearing, whereby, when the extruder is used, even at worst a very small force is exerted on the other bearings of the rotor (1) or stator (4, 5). By the method of the invention, a product can also be produced which contains cross-linked and at least partly oriented polyethylene.