摘要:
A sizing sleeve for controlling the diameter of plastic tube includes pressurized sizing sleeve portions in which fluid is injected under pressure about the tube circumference to form a lubricating layer. Drainage zones axially separate and isolate adjacent pressurized portions to allow independent temperature and pressure control. Each pressurized portion has flow stabilizer reducing variations in flow responsive to changes in the lubricating layer pressure. The flow stabilizer may comprise a high pressure fluid source and high pressure drop constrictor comprising fine apertures, which may be formed as grooves milled into end surface of abutting sizing sleeve segments.
摘要:
The invention relates to a method and apparatus for manufacturing ribbed piping, wherein a formable mass in a plastic state is extruded into a substantially cylindrical forming space of a corrugator, the forming space being delimited by forming molds movable in the production direction of the apparatus and having grooves on the inner surface thereof for forming rib flanges. A stationary kernel portion of a mandrel cools the interior surface of the piping and extends beyond the forming space constituted by the forming molds of the corrugator.
摘要:
An apparatus for manufacturing from a mouldable material a pipe having ribs on its outer surface and a smooth inner surface has a core including a shaft, a conically widening mandrel located downstream of the shaft in a direction of production and a kernel having an initial zone and an end zone respectively of substantially uniform diameters successively disposed downstream of the mandrel. An extrusion sleeve surrounds the core and forms with the core a nozzle for the material. The extrusion sleeve has a first end face located upstream of the kernel. Moulds encase the extrusion sleeve and the core, the moulds being movable along endless paths and having grooves on inner surfaces for forming the ribs on the pipe. A heater heats the initial zone of the kernel, the initial zone of the kernel being cylindrical. A first cooler cools the end zone of the kernel. A second end face of an upstream outset of the end zone of the kernel conically widens in the direction of production from a smallest diameter substantially corresponding to the diameter of the initial zone to a largest diameter.
摘要:
A method for the manufacture of a heat fusion fitting, which comprises i) forming a body (1) comprising at least a first layer of a first cross-linked polymeric material, ii) embedding or partly embedding a ferromagnetic heating element (11, 12) in a second polymeric material (13, 14) to form an insert (7, 8), the ferromagnetic heating element (11, 12) having a Curie temperature equal to or greater than the crystalline melting point or softening point of the second polymeric material (13, 14), and iii) assembling the body and the insert (7, 8) to form the fitting.
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:
A method for renovation of pipelines, comprising introduction of lining layers into the existing pipeline, the lining layers corresponding in length to the length of the pipeline to be renovated. The lining layers consist of fusible polymers and are presurized and fused together by the introduction of a heat source into the inside of the innermost lining layer.
摘要:
A method for joining a first tubular member to a second tubular member. The method provides a stretchable and compressible welding ring having a flexible inner ring, a resistance coil wound around the inner ring and at least one layer of plastic coating the resistance coil. The method includes the step of arranging the first and second tubular members in overlapping relation with an end of the first tubular member inserted into an end of the second tubular member and with the welding ring encircling the first tubular member and compressed between the first and second tubular members. The method also includes the step of applying electric energy to the resistance coil to melt the at least one layer of plastic so that, upon cooling, the respective ends of the first and second tubular members are welded to the welding ring.
摘要:
The invention relates to a method and an apparatus for the extrusion of plastic pipes. Today, plastic pipes are provided with a sleeve in such a manner that the end of the pipe is heated, whereafter the end is expanded by means of a mandrel or a pressure medium. This step requires a separate sleeve machine, and it also takes plenty of time and consumes thermal energy. According to the invention a sleeve (22) is formed in connection with the extrusion of a pipe in an apparatus in which a mandrel (8) is surrounded by chill moulds (1, 2) moving in the axial direction of the apparatus. The sleeve is formed by providing some of the chill moulds with a recess (16) the shape of which corresponds to that of the sleeve (22) and by pressing a plasticized plastic hose (11) extruded through a nozzle (10) against the walls of the recess in the area thereof by means of pressure air.
摘要:
A plastics pipe having a stabilized inner layer, wherein the inner layer comprises an extruded thermoplastic polymer comprising at least one polar stabilizer, wherein: (i) the thermoplastic polymer is provided with pendant polar functional groups, and/or (ii) the thermoplastic polymer comprises an effective amount of at least one filler provided with pendant polar functional groups, and/or (iii) the thermoplastic polymer comprises a blend of a non-polar thermoplastic polymer and a thermoplastic polymer provided with pendant polar functional groups.