Abstract: An apparatus for cutting slots in corrugated and twin-wall pipes that have annular elevations alternating with annular impressions, comprises a machine frame with a pipe duct and a lifting carriage for moving a pipe through the pipe duct. Two groups of holding and centering levers are provided which are engageable with a pipe for straightening and retaining the latter axially and radially. Further, saws are provided which are disposed between two groups of holding and centering levers on the machine frame and which are movable to reciprocate lineally and radially in relation to the axis of the pipe duct.

Abstract: An apparatus for the manufacture of corrugated pipes of thermoplastic plastics, which has circulating mold segment halves disposed in two opposite rows subsequent to an injection head, includes a wedge element for separating the mold segment halves. This wedge element is displaceable parallel to the direction of production. Further, grab equipments are provided to be displaceable,counter to the direction of production, by which one additional mold segment half at a time can be moved to the downstream end of a molding path, removed from the latter in the direction of production and moved into a parking position.

Abstract: An apparatus for the manufacturing of plastic pipes has half shells of which two at a time combine as a pair to form a mold. It is provided with a temperature-regulating bell. Supply lines are formed as flexible supply hoses of temperature-resistant plastic material. A line conduit accommodating them is provided with a protecting tube, which accommodates the supply hoses and which is provided with a heat insulation towards an injection head.

Abstract: In a method for connecting pipe pieces of corrugated pipes to form a pipe, which is to be used in particular as a protection pipe for communication cables or light wave guides, external pipe segments are formed by appropriate cutting in the vicinity of the external pipe portions, which external pipe segments are inserted into recesses of welding sleeves. These welding sleeves comprise an outer ring and an inner ring, the inner ring not projecting radially beyond the inner pipe portions into the pipe. At least one of the rings is welded with the external pipe segments.

Abstract: For the continuous manufacture of a compound pipe with a spigot which is substantially smooth on its outside, the compound pipe including a smooth internal tube and an external tube provided with transverse grooves and welded together with the internal tube, an external tube and an internal tube are extruded, the latter into the external tube. While the spigot which is substantially smooth on the outside is manufactured, its external wall is pressure-relieved by compensation chambers.

Abstract: An apparatus for the manufacture of pipes having transverse profile features has a machine bed, on which half shells, which can be combined to form a mold, are rotatably and displaceably drivable. The half shells are pressed together on a molding path by guide rails, of which one is displaceable at right angles to the direction of production by hydraulically actuatable drives. Interlockings may be provided in addition, a locking member of which engaging with an associated locking recess.

Abstract: An apparatus for the manufacturing of plastic pipes has an injection head and half shells of which two at a time combine as a pair to form a mold. The injection head has at least one channel issuing in a substantially ring-shaped nozzle, which is delimited by two components one of which being adjustable for modification of the width of the nozzle. A component directly delimiting the nozzle is tiltable in relation to the central longitudinal axis, whereby an adjustment of the width with great sensitivity is attained for such a ring-shaped nozzle.

Abstract: For welding composite pipes together a welding ring is used, which bears against the side wall portions of elevations. It consists of thermoplastic material and is provided with an electric resistance heating. Prior to welding there is an annular gap between the front walls of the pipes to which annular gap a volume compensating groove is associated in the welding ring. A connection of the pipes in their region outside of their inner pipe is performed by an at least partial welding of the welding ring, the front walls bearing against each other in unwelded manner.

Abstract: For the continuous manufacture of a compound pipe with a pipe socket including a smooth internal tube and an external tube provided with transverse grooves and welded together with the latter, an external tube and an internal tube are extruded, the latter into the external tube. While the normal compound pipe is manufactured, gas is blown at a slight overpressure into the space beteen the external tube and the internal tube. When the pipe socket is produced, this space is vented so that a full-surface bearing of the internal tube against the external tube is achieved, to which end the internal tube is acted upon from its inside by gas under pressure.

Abstract: Pipes with special profile sections are produced by an apparatus with circuit guided half shells. The half shells combining to form a mold have mold walls extending about parallel to a mold space axis. Vacuum slits extend about parallel to the mold space axis to open into a mold space in each case at a place radially the most distant from the mold space axis.

Abstract: A plastic pipe for sewer pipe reconstruction has at least one spigot, the outer diameter of which is smaller than the outer diameter of the pipe. It has furthermore a socket end the outer diameter of which is substantially equal to the outer diameter of the pipe. Its inner diameter is substantially equal to the outer diameter of the spigot. In order to construct such a pipe that, while having high crushing strength, it has low weight and insensitivity to damage in the outer area, and can be used for short-pipe relining, the pipe and the at least one spigot have annular protrusions. Furthermore, the outer diameter of the protrusions of the spigot corresponds substantially to the inner diameter of the socket end. The pipe is very rigid.

Abstract: A partial-seepage drainage pipe includes a wall surface of circular profile which is corrugated over the majority of the pipe circumference. Adjoining the circular wall surface is a base having a bottom surface and side wall segments. The pipe has a mating sleeve molded on in one piece at one end, which is adapted to receive the free end of a corrugated pipe segment and has slit-like water seepage openings in the corrugated wall surface.In order to attain a tight mating-sleeve connection, the bottom surface of the base and the corresponding bottom surface of the mating sleeve are embodied such that they arch in a slightly convex fashion.

Abstract: An apparatus for producing a finned tube from synthetic plastics material has a moulding chamber which moves in the direction of production. Molten synthetic plastics charge enters this moulding chamber from which fins are moulded one after another, the fins being in each case formed individually one after another. In order to ensure this procedural measure, there are constructed in the surface of the molten plastics material present in the moulding chamber annular raised portions with conveying surfaces trailing in the direcetion of production. Corresponding conveying grooves are constructed in the half moulds which bound the molding chamber. These measures ensure an accurate contour of the tube which is to be produced, ensuring that a reverse flow of molten plastics charge and its combustion will be prevented.

Abstract: A plastic corrugated tube, in the outer wall of which has a circular ring corrugation, is provided on one end with an integrally molded-on plain coupler having an approximately cylindrical inner face. Its inside diameter (d) is substantially equal to the outside diameter (d) of the corrugated tube, and the circular rings that form the corrugation and are spaced apart from one another by the distance (T) in the longitudinal direction of the tube each have the approximate cross section of a trapezoid tapering toward the outside; to this end, they have an approximately annular-cylindrical outer wall section (a) and slightly inclined side wall sections adjoining the outer wall section.

Abstract: A plastic corrugated sheathing hose adapted for electric cable installation and producible in one continuous operation, includes a longitudinal slit along its side. Each edge of the hose adjacent the slit is complementarily configured to form a detent or snap-locking closure releasably engageable in overlapping relationship. After insertion of a cable through the sheathing hose slit, closure of the hose is accomplished by pressing overlapped complementarily configured together. Closure of the hose in this manner results in a substantially gas-tight and waterproof cable enclosure accomplished in one operation with the inlaying of the cable.

Abstract: An apparatus for the production of plastic pipes with transverse grooves comprising half shells each having a mold recess which are arranged on a machine bed driven in a cycle. The half shells are assembled in pairs in a molding path to form a complete mold, the injection head of an extruder being arranged at the beginning of the molding path. Furthermore, the half shells are provided with vacuum channels, each vacuum channel being connected to a respective mold recess. The vacuum channels are joined into vacuum connections formed in the machine bed, and the half shells are provided with cooling channels which join into cooling water inlets and outlets in the machine bed. In order to ensure an exact setting of the half shells during the molding operation, the cooling channels, on the one hand, and the vacuum channels on the other hand, in a given half shell are completely separated from each other.

Abstract: An apparatus for cutting openings in pipes of cuttable material, in particular in plastics drainage pipes has at least one cutter head carrying at least one cutter, the cutter head rolling at least in part on the periphery of the pipe and being positively driven for this by means of a planetary gear. By virtue of this, the cutting edge of the cutter moves around the pipe in an epitrochoid. The cutter head is provided with ridges engaging in transverse corrugations in the outer wall of the pipe.In order to be also able to cut openings in pipes formed at least in part with annular corrugations over their periphery, at least the cutter head is provided with helically extending ridges and the at least one cutter is disposed parallel to these ridges.

Abstract: A process for the manufacture of a flat-shaped hollow body through the use of a forming die, wherein mold segment halves move continuously along a forming die and which, upon entering the forming die, are moved in an operating direction facing each other in pairs in a closed mold in tight proximity to each other. The mold is injected with warm thermoplastic hose stock which is shaped under vacuum action in the mold. In order to produce flat-shaped hollow bodies on a continuous basis the hose stock is subjected to vacuum action over at least a portion of its cross section even before mold segment halves are brought together and is pressed together accompanied by the formation of welds and the creation of hollow spaces over a portion of its cross section.

Abstract: In the manufacture of double-wall plastic tubing in which the outer wall has transverse corrugations and the inner wall is smooth, in the case of annular transverse corrugations the air pressure between the two walls cannot be balanced with the external air pressure, resulting in deformations of the inner tube. To permit an equilibrium of pressure before the inner wall hardens, openings are pierced in the outer wall or openings are produced between the two walls for communication between the inner chambers of the transverse corrugations. After the hardening of the inner tube, these openings are reclosed by fusion.

Abstract: An apparatus for the manufacture of transversely contoured tubing from thermoplastic material. The tube emerges in the plastic state from an extrusion nozzle and is guided into a mold composed of a plurality of mold sections in series, with inner side working surfaces forming the transverse contours. Each of the mold sections is composed of two mold halves which are arrayed along a straight molding run in two confronting rows and which are circulated. In the circulation, the first two mold halves are moved apart and out of the molding run at the end of the molding run and are guided to a return run on which they are separately returned to the beginning of the molding run where they are rejoined to the preceding mold half. The mold halves are guided on the return run in a continuous, accelerated and then decelerated movement by a transfer mechanism which couples and uncouples from the mold halves as actuated by pneumatic cylinders under the control of limit switches.