DE102013111960A1 - Process for the continuous production of plastic pipes - Google Patents

Abstract

The present invention relates to a method for the continuous production of tubes (20) in which by means of an extrusion device, a pipe string is extruded axially continuously, which has at least one at least partially in the axial direction extending hollow chamber (28). According to the invention, in at least one hollow chamber, either in the production of the tube or subsequently a fiber filled, which increases the weight of the tube. This makes it possible, first using a reduced amount of raw material to extrude a plastic pipe with reduced weight, which can be sunk by ballasting in a body of water. This production technique is particularly advantageous for a continuous extrusion of pipes with comparatively large diameters of, for example, 1 m or more, which can be continuously manufactured in long lengths and subsequently transported by sea.

Description

The present invention relates to a method for the continuous production of plastic pipes in which by means of an extrusion device, a pipe string is extruded continuously axially, which has at least one at least partially extending in the axial direction of the hollow chamber.

From the EP 0 318 434 A2 a method of the type mentioned is known in which plastic pipes with hollow chambers in the form of circular ring segments are extruded axially. These hollow chambers can be filled with a thermal insulation material, in particular a foam such as polystyrene. The pipes are used in particular as electrical installation pipes or for the passage of gaseous or liquid media. Since the foam used to fill the hollow chambers has a low density which is lower than that of the plastic pipe material, the filler in the hollow chambers is not suitable as fiber to weight the pipe.

The object of the invention is to provide a method for the continuous production of plastic pipes with the features of the aforementioned type, which makes it possible to weight the tube by means of a fiber, so that it is suitable for laying in a body of water in a specific method, in which the tube first floats on the surface of the water and is later sunk.

The solution to this problem provides a method for the continuous production of plastic pipes of the type mentioned above with the features of the main claim.

According to the invention it is provided that in at least one hollow chamber either in the manufacture of the tube or subsequently a dietary fiber is filled.

The inventive method makes it possible to produce in a continuous process a non-limited in its axial length pipe made of plastic, which has in the axial direction of the tube extending hollow chambers (cavities). In these hollow chambers can be introduced a dietary fiber, so that you can increase the density per tube length unit to sink a first floating transported pipe for laying on the bottom of a water (maritime lay).

The production of pipes of the aforementioned type is particularly interesting technologically particularly when plastic pipes are to produce with relatively large diameters. These have hitherto been produced predominantly in conventional winding tube technology with resulting finite tube lengths. This finite length of pipe has hitherto been less problematical in that, in the case of pipes with larger diameters, the necessity of transporting them to the place of use usually necessitated a length limitation. While rigid plastic pipes with smaller diameters of up to about 200 mm can also be wound up on drums, this is no longer possible for pipes with larger diameters. Consequently, the maximum length of a pipe string that can be transported by land is limited to approximately the length of the loading area of a truck.

On the other hand, if other methods are used to transport tubes of comparatively large diameters, such as more than 1000 mm, also in lengths exceeding the transport length of a truck, continuous production of unlimited length is particularly advantageous. Here, for example, offers the production of such large pipes in the vicinity of a body of water, so that it is possible to extrude these tubes continuously and run at the end of the extrusion line the tubing directly into the water. Since the plastic pipes float on the water surface, long pipe strings can be towed by means of transport ships and thus transported to the place of use. The pipe extrusion can thus continue over long lengths of the pipe string, without it being necessary to cut the pipe string after extrusion of a limited transport for land transport length. The entire extrusion line can operate continuously without interruption, making overall pipe production more efficient than traditional winding processes.

Another concern of the present invention is thus the continuous extrusion of long mechanically loadable plastic tubing with large diameters, especially in the range of more than 1000 mm in diameter, in a rational economical manufacturing process.

The dietary fiber according to the invention, which is filled into the hollow chambers, can be, for example, a mineral fiber. This may be, for example, a bulk material in free-flowing form or a slurry, a pulpy viscous substance, for example a concrete mixture. The subsequent filling of this fiber in the hollow chambers in this section of the method can be done, for example, after holes have been drilled in the hollow chambers, so that Interior of the hollow chambers is so accessible and can be filled. These holes can then be closed again, but this is not necessary if, for example, a hydraulically curing mixture is used as fiber since this then hardens and thus closes the filling openings.

If one fills at least one hollow chamber of the plastic tube after its extrusion with a dietary fiber, this dietary fiber in the hollow chamber should preferably have a density which is at least about 1.3 g / cm ³ . The plastics used for such plastic pipes such as polyolefins have a density of less than 1 g / cm ³ and are thus lighter than water. In the case of polyethylene, the density is, for example, in the range of 0.87-0.97 g / cm ³ , depending on the type, and about 0.89-0.92 g / cm ³ in the case of polypropylene. In order to weight the tube through the fiber so that it can submerge in water, it is advisable to use fiber, whose density is a little over 1 g / cm ³ , preferably therefore, the fiber in the hollow chamber has a density that is at least about 1.3 g / cm ³ .

For example, mineral fiber may be used, such as sand, cement, quartz, rock flour, gravel, split, metal particles or glass.

According to a preferred embodiment of the task solution according to the invention, a pipe string can be continuously extruded so that already emerging from the tube head nozzle extruder strand has several extending in the axial direction of the tube, distributed over the circumference of the tube arranged hollow chambers.

These hollow chambers may for example have a cylindrical, rectangular or polygonal cross-section.

According to a possible development of the present invention, it is also possible for a tube to be produced in which at least one hollow chamber into which a fiber material is filled is located in the region of a middle layer of the tube. Thus, for example, a tube having a solid core layer and a middle layer following this core layer outwardly may be extruded in a single or multiple sequential steps, with hollow chambers in the middle layer. In this hollow chambers in turn a fiber can be filled and this tube is then coated again, for example, by extruding again with a solid outer layer.

The features mentioned in the dependent claims relate to preferred developments of the task solution according to the invention. Further advantages of the invention will become apparent from the following detailed description.

Hereinafter, the present invention will be described in more detail by way of embodiments with reference to the accompanying drawings.

Showing:

1 a schematically simplified cross-section through a pipe according to an exemplary variant of the present invention;

2 a simplified schematic view of an exemplary plant according to the invention for the production of pipes.

First, it will open 1 Referenced. This shows an exemplary pipe according to the invention 20 made of plastic in cross section. This has a series of hollow chambers 28 on, extending in the axial direction of the tube 20 extend and which may for example have an approximately cylindrical cross-section as shown here. But there are also rectangular, polygonal or other cross sections possible. These hollow chambers are inventively preferred already during the extrusion of the tube 20 brought in. This is procedurally readily possible by using a suitable extrusion tool on the pipe head in the extrusion of the pipe string. Since during extrusion of a plastic pipe with a solid wall of the melt strand exits through an annular die gap on the pipe head of the extruder, one can here, for example, use an annular nozzle having additional mandrels or rods, in their areas no melt emerges, so that an annular melt strand with distributed over the circumference arranged axially extending cylindrical cavities results, the desired in 1 corresponds to the illustrated pipe cross-section. In this way, such a tube can be 20 with hollow chambers 28 in a single manufacturing step in continuous extrusion in pipe runs whose axial length has no limit. The cylindrical hollow chambers have the advantage that a very considerable part of the plastic raw material used can be saved, which leads to significant material savings, in particular in the production of pipes with comparatively large diameters of, for example, 1 m or more. At the same time, the tubes produced are mechanically stable enough, but have a significantly reduced weight compared to a solid wall tube.

2 shows in a simplified schematic representation of a system according to the invention for the extrusion of long pipe strands, which can be connected to a hall, in which an extrusion line, for example, in an open area more investment areas. Following a deduction 13 , of the the axial transport of the extruded tubing 20 causes a filling station can be found downstream in the extrusion line 21 that the pipe 20 goes through and in the pipe 20 with a fiber 22 is filled. This fiber can, for example, from a storage container, for example, from the back of a truck 23 in the before by means of 1 described hollow chambers 28 of the tube are filled. This may be a mineral fiber, for example as a bulk material in free-flowing form or a slurry, a pulpy viscous substance, for example a concrete mixture. The subsequent filling of this fiber in the hollow chambers 28 In this section of the method, for example, after holes have been drilled in the hollow chambers, so that the interior of the hollow chambers is so accessible and can be filled. These holes can then be closed again, but this is not necessary if, for example, a hydraulically curing mixture is used as fiber, as this then hardens and thus closes the filling openings. Alternatively, however, it can also be provided that the fiber is already in an earlier stage of the process in the hollow chambers 28 is introduced. For example, the dietary fiber can also be introduced into the hollow chambers immediately after the extrusion. It is important in this context that the selected fiber has a sufficiently high density that increases the weight of the tubing so strong that it can then sink into a body of water, which is in a tubing of a conventional polyolefin with a density of less than 1 g / cm ^{3 would} not be the case.

The site 24 on the pipe 20 continue towards the waters 25 can be downhill to the water, as in 2 is shown. That in the axial direction of the waters 25 to conveyed pipe 20 can on suitable camps 26 be stored on the ground, which allow a sliding conveyance of the pipe without the risk that it will be damaged. For this purpose, for example, use vehicle tires or similar bearings of rubber or a suitable material with reduced friction. In the further feed path then passes the tube 20 into the water 25 , which may be the sea, if the production of the pipes takes place directly in the coastal area. This is particularly interesting for the production of so-called sea discharge lines for waste water or the like, which can then be transported via the water directly to the installation site. As long as there is air in the pipe 20 It floats on the water surface even after the introduction of the fiber 22 , The pipe 20 can in the further flow on the surface of the water by means of suitable floating bearings such as air cushions 27 be supported, resulting in a stabilization of the pipe string.

Tube 20 This type, even with large diameters of more than 1 m, can be transported by sea as floating pipe strands of, for example, several 100 m by sea. When the desired length of pipe string is reached, it can be cut and removed so that the extrusion line continues to operate and the next pipe into the water 25 can extrude expiring. A towboat can also drag several tubes of the mentioned length parallel next to each other and thus transport it in a floating manner. In this way, so can be transported to a pipeline with relatively little energy consumption with a single transport by sea miles. Here, the advantage over conventional large-diameter pipe production becomes clear, in which only lengths of less than 20 m could be transported on the back of a truck in the rule. Accordingly, a significantly larger number of welds was necessary to connect these pieces of pipe together at the installation site. The sinking of the pipes 20 At the place of installation can be done by the pipes are flooded with water, because then leads due to the fiber in the pipe wall, the increased weight of the tube to the fact that the tube sinks. A premature full run of the tubes with water can be prevented by the tubes are initially closed at the front by covers or the like. These covers are then removed while flooding.

LIST OF REFERENCE NUMBERS

13

 deduction

20

 tubing

21

 filling station

22

 dietary fiber

23

 truck

24

 terrain

25

 waters

26

 camp

27

 air cushion

28

 hollow

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• EP 0318434 A2 [0002]

Claims (10)

Method for continuous production of pipes ( 20 ) in which by means of an extrusion device, a pipe string is extruded continuously axially, which at least one at least partially in the axial direction extending hollow chamber ( 28 ), characterized in that in at least one hollow chamber ( 28 ) either in the manufacture of the tube or subsequently a dietary fiber ( 22 ) is filled. A method according to claim 1, characterized in that in at least one hollow chamber ( 28 ) filled fiber ( 22 ) comprises a bulk material. A method according to claim 1 or 2, characterized in that in at least one hollow chamber ( 28 ) filled fiber ( 22 ) has a density that is at least about 1.3 g / cm ³ . Method according to one of claims 1 to 3, characterized in that a mineral fiber ( 22 ) is used. Method according to one of claims 1 to 4, characterized in that the fiber ( 22 ) Comprises sand, cement, quartz, rock flour, gravel, split, metal particles or glass. Method according to one of claims 1, 3 or 4, characterized in that the fiber ( 22 ) is a slurry or pulpy viscous substance, especially a concrete mix which is filled into the hollow chambers. Method according to one of claims 1 to 6, characterized in that a pipe string is continuously extruded so that even the emerging at the pipe head nozzle of an extruder melt strand several in the axial direction of the tube ( 20 ) extending, distributed over the circumference of the tube arranged hollow chambers ( 28 ) having. Method according to claim 7, characterized in that the hollow chambers ( 28 ) have a cylindrical, rectangular or polygonal cross-section. Method according to one of claims 1 to 8, characterized in that first a pipe string with extending in the axial direction hollow chambers ( 28 ) is continuously extruded, in these hollow chambers then a fiber is filled and this pipe string is extruded into a body of water at its downstream end. Method according to one of claims 1 to 9, characterized in that a tube is made, in which at least one hollow chamber ( 28 ) into which a fiber ( 22 ), is located in the region of a middle layer of the tube.

Images