Abstract: A mold block which is used in a moving mold tunnel comprises first and second mold block sections which meet at their parting faces to close the mold block. Each mold block section has a product shaping interior surface and an air movement passage having an entrance at the base of each mold block section, a first opening to the interior surface and a second opening to the parting face of each mold block section. An air flow controller is provided between the parting face opening and the interior surface opening of the passage in the first mold block section and an air flow controller is provided between the entrance and the interior surface opening in the passage in the second mold block section.

Abstract: An extruder for use in a plastic extrusion process comprises a plurality of extruder members. Each extruder member comprises a plate portion and a hollow tubular portion perpendicular to the plate portion. The plate portions of the extruder members are located side by side with one another and define a first plastic handling part of the extruder in which there is firstly a feeding and then a transition of plastic material fed to the extruder. The tubular portions of the extruder members which are telescopically interfitted with one another define a second plastic handling part of the extruder for metering of plastic flow output from the extruder.

Abstract: A molding apparatus which is used in a continuous molding operation includes an endless looped track, track carriers which are moved around the track to and from a product shaping mold region and a transfer system for replacement of mold block members used in the apparatus. The transfer system, which operates without interrupting the molding operation includes transfer carriers controlled to move synchronized with the track carriers at a transfer location remote from the mold region and actuators which slide the mold block members between the track carriers and the transfer carriers at the transfer location when the transfer carriers are synchronized with the track carriers.

Abstract: A method for differentiating or detecting particles in a sample in which several classes of particles may be present by identifying signal segments of time-resolved, optical raw signals from the sample on the basis of single photon detection (single pulse detection), wherein the sample contains at least two classes of particles; the sample is illuminated by a light source; the optical raw signals emitted by the sample, which are derived from at least one measuring volume element V, V≦10−12 l, are detected with at least one detector unit; at least one particle generates a signal fraction during its residence in the measuring in the measuring volume element; a signal segment of the optical raw signals is determined by the particle's actively and/or passively entering and then leaving again the measuring volume element; the optical raw signals are segmented into arbitrary segments; at least one set of statistical data based on the optical raw signals is established for at least one arbitrarily chos

Abstract: A pipe molding apparatus for forming double walled plastic pipe comprises an extruder which feeds first and second parisons of flowing plastic material to a moving mold tunnel to make respectively the outer and inner walls of the pipe. The moving mold tunnel includes a cooling plug over which the second parison moves to form the inner pipe wall while the outer wall of the pipe is formed against the interior surface of the mold tunnel. An air assist is provided internally of and helps to move the inner parison onto the cooling plug.

Abstract: A mold block which is used in a moving mold tunnel comprises first and second mold block sections which meet at their parting faces to close the mold block. Each mold block section has a product shaping interior surface and an air movement passage having an entrance at the base of each mold block section, a first opening to the interior surface and a second opening to the parting face of each mold block section. An air flow controller is provided between the parting face opening and the interior surface opening of the passage in the first mold block section and an air flow controller is provided between the entrance and the interior surface opening in the passage in the second mold block section.

Abstract: A spider in an extruder head has a plurality of internal plastic flow passages extending axially through the spider and a spider leg between each flow passage. Each spider leg has upstream and downstream spider leg parts. The upstream part is a flow splitter which splits flow of plastic along the extruder to the spider leg into a plurality of independent plastic streams. The downstream part of the spider leg has a plurality of flow guides staggered at different radial depths in the spider leg with all of the flow guides being directed at one another to guide the bonding of independent plastic streams.

Abstract: A method of forming a plastic product comprises extruding molten plastic into a mold having a mold wall with product shaping interior face. After shaping the product in the mold, the method includes introducing gas via a gas inlet through the mold wall onto the product to cool both the product and the mold and then discharging the gas from the mold at a location remote from the gas inlet.

Abstract: An extruder and mandrel assembly is used in a plastic pipe forming apparatus. The mandrel itself is formed from a pair of elongated tubes comprising an inner tube and an outer tube separated from the inner tube by a plastic flow path through the mandrel. The inner tube is formed by a pair of sleeves comprising an inner sleeve and an outer sleeve which is held within the mandrel by the inner sleeve. The inner sleeve is secured at its upstream end to the spider of the extruder head and the outer sleeve is secured by a releasable interlock to the inner sleeve with the releasable interlock being accessible from the downstream end of the mandrel. Therefore, the mandrel does not have to be released from the spider of the extruder head in order to remove the outer sleeve of the inner tube of the mandrel.

Abstract: A plastic part forming apparatus includes a mold tunnel into which molten plastic is fed to form the plastic part. The mold tunnel is made from thermally conductive material and has a part shaping interior face which is non-reflective such that the interior surface has high capacity to absorb heat energy from the plastic fed into the mold tunnel. The thermally conductive material then dissipates the heat energy from the mold tunnel.

Abstract: A pipe cutting apparatus comprises a housing with a pipe passage through the housing, a rotatable collar and a rotatable ring both of which rotate about the pipe passage and a pipe cutter mounted on the collar. The pipe cutter is movable inwardly toward and outwardly away from the pipe passage and has a drive gear which engages the ring such that differences in rotating speeds between the collar and the ring operate the drive gear to produce movement of the pipe cutter.

Abstract: A mold apparatus has a plurality of sets of mold block parts which move to and from a product forming mold tunnel along the apparatus. Each set of mold block parts has at least one liquid receiving channel and a liquid supply is provided for supplying cooling liquid to the channel. The ends of the channel are open for feeding the cooling liquid into one end and draining the cooling liquid from the other end of the channel when the set of mold block parts is in the mold tunnel and seals are provided to prevent leakage of any cooling liquid trapped in the channel when the mold block parts are away from the mold tunnel.

Abstract: In a method of forming a hollow product in a molding apparatus having an upstream and a downsteam end a parison of thermoplastic material is extruded in a molten state from a heated extruder at the upstream end and moved through a product shaping region towards the downstream end of the apparatus. The material is cooled by passing a cooling medium internally of the product from the downstream end towards the upstream end of the apparatus.

Abstract: Lengths of ribbed tube (10) having ribs which upstand appreciably from the main body of the tube may be coupled together using novel coupling ends (12, 112 and 14, 114, 214) of the tube. Alternatively, such ribbed tube may be coupled to plain walled tube (100). The lengths of tube are provided with first and second cuffed ends, the first end being a smooth walled cuff having a cuff having only shallow ribs reduced height and the second end being belled to couple with a first end of another tube or with plain walled tube smooth first end and the billed second end may be formed to respective outer and inner diameters for good sealing between them.