DE4139649A1 - Thick-walled plastic tube - obtd. by extruding two tubes vertically down into cooling bath and comprising thick scrap plastic outer and virgin polyethylene@ inner - Google Patents

Abstract

The invention relates to a thick-walled plastic tube and a process and appts. for mfr.. The pipe comprises at least two concentric coextruded pipes fused together in the molten state. Ungraded plastic scrap, chiefly polyethylene, forms the external pipe, while the inner pipe is mfd. in virgin polyethylene. Both pipes are coextruded in a vertically downward direction and below the extrusion die is a fluid container which receives the extrudate. By coordinating the densities of the polymer and the fluid in the container, the haul-off of the extruded pipe can be performed under predetermined tension and compression loading to prevent deformation. USE/ADVANTAGE - The process and appts. produce a thick-walled plastic tube, e.g. waste water tube, with adequate properties and reuses scrap polymer from many sources.

Description

The invention is directed to a thick-walled plastic tube and a Method and apparatus for its manufacture, the art fabric tube made of at least two concentric, co-extruded and warm plastically connected pipe jackets, of which at least one consists single-variety and at least one other from processed, secondary Plastic is made.

A multi-layer plastic tube is known from EP 03 58 178 A1, an outer wall layer and an inner wall layer made of polypropylene or consists of polyethylene and an intermediate wall layer through again used, ground, glass fiber reinforced polypropylene is formed.

A generic tube is known from DE 31 02 350 A1, wherein the outer jacket made of primary polyvinyl chloride and the inner jacket made of secondary polyvinyl chloride exist, the two pipe jackets through Coextrusion are made.

These previously known tubes are relatively thin-walled Pipes with a relatively small diameter.

Proceeding from this, the invention is based, under Ver evaluation of secondary plastic material a thick-walled, comparative wise large diameter pipe, such as a sewage or District heating pipe to create, which with advantageous use is inexpensive to produce.

This object is achieved according to the invention by a tube, the little of which Mostly an outer jacket made of unsorted plastic waste is based on polyethylene, and at least one inner jacket consists of pure plastic based on polyethylene.  

This construction makes it possible to dispose of plastic waste from the household, Trade and industry, mixed and dirty, to process that in large quantities are available and accordingly not just a cost-effective one form the initial product, but at the same time also the Disposal of this plastic waste becomes possible.

A finished tube of the type in question points in the radial direction low heat conduction, d. H. in other words, good insulation create on, so that it can also be used to transport steam and Liquids. In addition, the pipe is against heated media resistant. Furthermore, such tubes also have a sufficient mecha African stability, so that they can also be easily transported and have it laid.

As comparable pipes for drainage and sewerage are sol che known from concrete or stoneware. Cast iron pipes and Steel pipes with concrete lining used. These previously known pipes ha ben compared to a pipe according to the invention described above Disadvantage that they only run in lengths of up to 2 m due to the risk of breakage can be manufactured and it is often necessary to use these pipes inside to line a smoothing mass. Stoneware pipes need due their low elasticity when laying with sand carefully under be fed to avoid stress cracks. While transporting Great care must be taken to ensure an even application of force when loading and Unloaded. The well-known cast and steel pipes must usually also be provided with protective lining.

In contrast, it is clear that a tube designed according to the invention is not only cheaper to manufacture, but also in his hand availability and in its stability properties and in terms of Weight during and after laying extremely advantageous properties having. There is also a special feature of the tube according to the invention in that it enables the recycling of mixed waste, which comes from conventionally as for very large products, such as B. Park  benches and noise barriers were considered to be usable. It can in particular in the case of partial fiberglass production Waste that can hardly be incinerated is recycled because of the Glass content leads to sticking.

The invention is also directed to a method for producing a at least double-walled plastic pipe of relatively large wall thickness and relatively large diameter, whereby this method is characterized records that the at least two pipe jackets in the vertical direction be co-extruded and bonded warm plastic, with below the Extrusion nozzles at least one liquid container is arranged, the the pipes vertically in the extrusion direction, the density of the Plastic material of the tube and the liquid in the container like this are coordinated that the withdrawal of the extruded tube strand with defined tensile or compressive force.

The measure according to the invention makes it possible to use even thick-walled ones and extru pipes with a high specific length weight dieren without the risk that the pipes after extrusion harden too slowly or before a deforma finally hardens tion subject.

In a further embodiment of this method it can be provided that extrude the tubes around a cooled calibration or guide core be dated. In the interior, between the ring nozzles coolant can also be introduced, which is then on the inside wall runs down.

Conveniently it is provided that according to the depth of the liquid cut the corresponding extruded pipe length of the pipe string and for further cooling in the coolant is shifted until the finished extruded pipe section removed and laterally in horizon valley direction is transported away.  

The further transport of the finished pipe sections can, for. B. by means of a Follow revolver-like rotary motion, taking along the rotary path Measuring devices for the finished and hardened pipe sections are arranged.

The invention is also directed to a device for through implementation of the method described above, which is distinguished by at least two extruders for feeding the hot plastic art material and a downstream ring nozzle, this at least two ring nozzles are arranged concentrically to one another, and through a liquid basin arranged below the ring nozzles one of the narrow depth corresponding to the pipe sections to be produced and by a separating device for separating the plastic pipe strand after extrusion of a corresponding section.

Furthermore, the device can have a cooled core within the two Include ring nozzles.

Conveniently, the device also has a turret-like transport device for removing the extruded and cut Pipe sections on.

Below is a preferred embodiment of a fiction measured device based on a preferred embodiment described. Show:

Fig. 1 is a partially sectioned side view of an inventive device and

Fig. 2 is a plan view of an inventive device.

The schematic representation according to the drawing essentially serves to the essential parts of a device according to the invention and the To explain the principle of the manufacturing process. It became conscious constructive details omitted.  

A device shown in the drawing comprises two extruders 1 , 2 , one of which is an extruder 1 for the comparatively strong, outer wall and the extruder 2 is intended for the comparatively thin, inner lining. The two extruders 1 , 2 extrude into a tube head 3 , which comprises two ring nozzles, not shown in the drawing, for coextrusion of the two tube jackets. A feed line 4 for cooling liquid opens into this pipe head 3 and runs down the inner wall of the freshly extruded pipe section.

To cool the outside, a calibration cooling device 5 is provided, which surrounds the freshly extruded tube 6 . In a preferred embodiment, the device 5 can comprise a plurality of plates arranged one above the other and having a central recess for the tube 6 , the cooling liquid being introduced from above into the uppermost plate and then coming down from there and from the outer wall of the plate Tube 6 is taken.

To control the feed of the freshly extruded tube 6 down a feed device 7 may be provided, the z. B. is controlled depending on the speed of the extrusion speed.

The extrusion speed and the feed device 7 determine the speed at which the tube 6 is drawn off and when it is immersed in the coolant reservoir 8 , which is shown in broken lines. The pipes are removed from the cooling liquid pool 8 by means of a bevel 9 . For this purpose, the tubes are first placed on a ring rail 10 and rotated thereon in a revolver-like movement from the original extrusion position, as indicated by dashed lines at 11 in the drawing.

In the cooling liquid basin 8 , the liquid level 12 is set to such a height that the upper side of the pipes there for cooling is covered. The cooling liquid pool 8 is fixed by a support frame 13 , a central control being indicated at 14 .

Claims (8)

1. Thick-walled plastic pipe comprising at least two concentric, coextruded and thermoplastic-connected pipe jackets, at least one of which consists of single-grade and at least one further of refurbished, secondary plastic, characterized in that the at least one outer pipe jacket consists of unsorted plastic waste predominantly based on polyethylene, and that the at least one inner jacket made of pure plastic on a polyethylene basis. 2. A method for producing a plastic pipe according to claim 1, characterized in that at least two pipe jackets in the vertical Direction co-extruded and connected hot plastic, under At least one liquid container is arranged half of the extrusion nozzles is, which receives the pipes vertically in the direction of extrusion, the Density of the plastic material of the pipe and the liquid in the Containers are coordinated so that the pulling of the extru dated pipe string with a defined tensile or compressive force. 3. The method according to claim 2, characterized in that the tubes at simultaneous cooled external calibration by a cooled calibration or Guide core are extruded around. 4. The method according to claim 2, characterized in that after a extruded tube length corresponding to the depth of the liquid pool the pipe string is cut off and turned to the side until it is cooled the finished extruded, cut pipe section in a horizontal direction tion is transported away. 5. The method according to claim 2, characterized in that the next transport of the finished pipe sections by means of a relvo-like turn Movement takes place, the finished pipe sections using an Ent device taken laterally offset to the extrusion position will.   6. Device for carrying out the method according to claims 2 to 5, characterized in that at least two extruders ( 1 , 2 ) for supplying the hot plastic material and a downstream ring nozzle are provided, these at least two ring nozzles being arranged concentrically to one another, and that a liquid basin arranged below half of the ring nozzles ( 8 ) with a depth corresponding to the length of the pipe sections ( 6 , 11 ) to be produced and a separating device for separating the plastic strand after extrusion of a corresponding section are provided. 7. The device according to claim 6, characterized in that a cooled core and a cooled external calibration ( 5 ) are arranged below the at least two ring nozzles. 8. The device according to claim 6, characterized by a turret-like transport device (ring rail ( 16 ) for removing the extruded and cut pipe sections ( 6 , 11 ).