A two stage mold block transfer station is used the exit of a moving mold tunnel to quickly move mold blocks to a clear position relative to the molded product. Once in the clear position the mold block is rotated and provided to a return drive moving the mold block back to the inlet of the moving mold tunnel. By moving the last mold block of the moving mold tunnel primarily away from the longitudinal axis of the mold tunnel less mold blocks are required. Various arrangements for moving of the mold blocks can be used achieve this advantage.

A webless corrugated dual wall foundation drain which is constructed as a hollow rectangular tubular member with an inner corrugated wall formed of HDPE and an integral outer smooth wall formed of the same material. The outer smooth wall of the foundation drain is attached to and integrally formed with the corrugations of the inner corrugated wall through a coextrusion process, thereby significantly enhancing the vertical beam stiffness of the foundation drain and eliminating the need for an internal supporting web.

A pipe coupling for triple wall corrugated plastic pipe includes a triple wall corrugated bellmouth connector that is of a unitary construction with one end of the corrugated plastic pipe. This bellmouth connector is of higher strength and in cooperation with the two wall corrugated spigot provides a high strength coupling. This coupling includes the bellmouth connector and spigot that are made inline with the corrugated pipe. A method for the manufacture of the pipe includes controlling of an air pressure on the outside of a formed two wall corrugated pipe as an exterior third wall is secured thereto.

This invention provides for a component forming a part of a breathing tube, or forming the breathing tube, for example as a part of a breathing circuit for respiratory therapy. The component comprising a tubular body having a foamed wall. The foamed wall can be formed from extrusion of a single extrudate. The foamed wall is of a sufficient minimum optical transparency such that, in use, there is enabled the visual detection of a liquid (or condensate that may have formed) within the tubular body.

The present invention provides a corrugated tube and a method for manufacturing the same capable of improving workability in press-fitting work of a pipe or a quick connector. A corrugated tube includes a flexible section having a first corrugated section and a second corrugated section, and straight sections integrally formed at both ends of the flexible section respectively. A length of valley portions in an axial center direction is larger than a length of valley portions in the first corrugated section, thereby allows a pitch P2 of mountain portions in the second corrugated section provided between the straight section and the first corrugated section to be larger than a pitch P1 of mountain portions in the first corrugated section.

A method and apparatus for forming a pressure vessel liner are disclosed. One method includes forming an extruded tube by extruding a parison through a die and a mandrel and forming main body sections and return line sections in the extruded tube according to a first pattern. A cross-sectional area of the return line sections is smaller than a cross-sectional area of the main body sections. The method further includes changing the pattern according to which the main body sections and the return line sections are formed from the first pattern to a second pattern without stopping the forming of the extruded tube and forming the main body sections and the return line sections in the extruded tube according to the second pattern.

Mold blocks of a pipe molding corrugator are provided with enhanced cooling capability due to the provision of cooling fins on the side portions of each mold block. Air can be forced between the fins and some exhaustion of the air can occur at the base of the fins adjacent the mold block cavity. With this arrangement, enhanced cooling of mold blocks is possible.

A method for producing an elongated article with a sheath. The sheath is extruded with a predetermined wall thickness in an extrusion unit. Following the extrusion unit in a feeding direction, a part of the still moldable material is built up with the aid of a molding unit during a molding process such that a molded part forms integrally on the sheath. The molding unit is moved according to the following working cycle: the molding unit is accelerated from a starting position in the feeding direction, then it is advanced in the direction of the elongated article and the molded part is formed, the molding unit is withdrawn from the elongated article, and the molding unit is decelerated and moved from an end position, counter to the feeding direction, back in the direction of the starting position.

Mold blocks of a pipe molding corrugator are provided with enhanced cooling capability due to the provision of cooling fins on the side portions of each mold block. Air can be forced between the fins and some exhaustion of the air can occur at the base of the fins adjacent the mold block cavity. With this arrangement, enhanced cooling of mold blocks is possible.

In the manufacture of double-walled corrugated extruded pipe it is desirable to form an integral connecting cuff that is of a single wall thickness and typically of a large diameter. The mold blocks and process parameters for forming of the cuff as part of an otherwise double-walled pipe requires a transition as the cuff moves past the die outlets. The present invention allows for accurate sensing and control of air pressure and temperature as the cuff moves past the die outlets. Improvements in both the die tooling and the method of manufacture are disclosed.