FI71610C - Plastic pipes with axial channels in the pipe wall and method of manufacturing the plastic pipe. - Google Patents

Description

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The present invention relates to a plastic pipe comprising an inner wall and an outer wall connected to each other by axially extending connecting partitions forming axially extending channels with a rounded cross-section.

Plastic pipes are known in which the axial channels are delimited by an inner and outer wall.

In the pipeline network, the outer wall may be damaged so that the groundwater may penetrate through the openings or cracks in said wall into the longitudinal channels, this groundwater may then have to mix with the sewage carried by the above-mentioned pipeline network.

Sewage treatment plants that treat sewage carried by a pipeline network are thus burdened by a large amount of groundwater that does not require treatment.

It is also possible that if there is damage or openings in the outer wall, the dirt from the pipeline network will enter the continuous channels, and out through these continuous channels and openings or cracks in the outer wall, causing serious contamination in the soil.

The present invention provides a plastic pipe of the above-mentioned type which does not have the above-mentioned drawbacks and which is provided with means which allow it to be connected to other pipes.

This is achieved according to the invention in that each channel is provided with a channel closing wall which communicates with the free sleeve end of the channel, which is preferably provided with an annular groove for receiving the closing member.

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First, each channel is equipped with shells located at a distance from the nearest free end of the pipe. It follows that each tube is individually closed, which solution prevents liquid from flowing out of the tube or flowing into the tube when the outer wall is damaged.

On the other hand, the connection of the closing wall to the sleeve end makes it possible to connect the pipe to another pipe.

The present invention, on the other hand, also relates to a method of manufacturing a plastic pipe comprising an inner and an outer wall which, when forming axial channels, are connected to each other by axial connecting partitions. At the ends of the channel, its walls, after being heated above the temperature required for plasticization, are pressed tightly against each other and the ends are expanded into a sleeve, providing a plastic tube with effectively closed axial channels and members for connection to another tube.

When the walls of the channel are pressed against each other, after they have been heated above the temperature required for plasticization, the end of the tube is subjected to a rotating movement, which has the advantage that the risk of corrugations is completely avoided when the channels are closed.

Due to this small rotational movement, the cross-sections of the continuous channels are gradually destroyed until the walls of the channel are completely connected to each other.

When the channels are closed by heating the plastic above the temperature required for plasticization and pressing the walls of the channel against each other, the pipe can be simultaneously provided with an end sleeve by enlarging the former.

The invention will be described below with reference to the accompanying drawings, in which some embodiments of the present invention are shown.

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In the drawing: Fig. 1 is a pipe according to the invention with a sleeve head and a groove, Fig. 2 is a perspective view of Fig. 1 along line II-II, Figs. 3a-3d show some details of the cross-sectional shape of the channel

Figures 1 and 2 show a known plastic tube comprising an inner wall 1 and an outer wall 2 which, when forming axial channels 4, are connected to each other by axial connecting partitions 3. Although in this embodiment the axis of longitudinal channels is parallel to the plastic tube axis, forms such that slightly helical longitudinal channels are formed.

This type of plastic pipe can be used to transport sewage, especially in a sewer network. However, they have the disadvantage that the water and the substances thrown into it flow in the channels themselves. This is quite inconvenient when, for example, the outer wall of such a pipe is more or less damaged, the inner wall of the plastic pipe being undamaged.

Such a situation can easily arise because these known pipes are specially made to reduce the consumption of plastic material in the pipes, in particular by making a thin inner wall 1 and a thin outer wall 2.

When the outer wall 2 is more or less damaged, water can easily penetrate through the longitudinal channels 4 into the pipeline network. Treatment plants must then purify more water than what the pipeline network normally carries. Namely, the groundwater may flow into the pipeline network through the channels 4 when they are open and mix with the sewage there.

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Water purification already requires a lot of energy, the consumption of which increases greatly when the water to be treated contains groundwater.

If the outer wall 2 is damaged while the longitudinal channels 4 are open, there is also the possibility that water will flow from the pipeline network through the channels 4 and the holes in the outer wall, which could cause serious soil contamination.

To eliminate all these above-mentioned difficulties, the end 5 of each pipe has an end wall 6 of the channel, which is connected to the sleeve 7.

Figures 3a-3d show how the ends 8 of the channel are sealingly pressed against each other after they have been heated above the plasticization temperature.

To do this, the end 8 of the plastic tube with axial channels between the inner and outer wall is heated and then pushed over the spreading pin to form a sleeve 7 with a groove 9.

In order to prevent the formation of corrugations during this operation, a slight rotational movement is applied to the end of the plastic tube by rotating the spreading pin 10, causing a gradual destruction of the partitions 3. The cross-sections of the channels 4 initially become elliptical, the ellipticity gradually increasing; eventually the walls fully coalesce and merge with each other under the influence of the temperature of the plastic material forming the barrier.

Figures 3a-3d show some details of the cross-sectional shape of the channel openings of the pipe according to the present invention when rotation occurs.

Such a tube, with the ends of the channels 4 closed, has proved to be very convenient in use.

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To form the groove 9, the spreading pin 10 is provided with an annular protrusion 11 for the groove 9.

Once the sleeve is formed, a small rotational movement is applied to the spreading pin 10 to prevent the formation of corrugations in the plastic tube.

In order to keep the inner diameter of the tube unchanged in the part which is not applied, the spreading pin 10 has a part 10a whose diameter corresponds to the inner diameter of the original plastic tube.

Claims (5)

6 71 61 O 1 · Plastic tube comprising an inner wall (1) and an outer wall (2) connected to each other by axially extending connecting partitions (3) forming axially extending channels (4) with a rounded cross-section, characterized in that each the channel (4) is provided with a channel closing wall (6) which communicates with the free sleeve end (7) of the channel, which is preferably provided with an annular groove (9) for receiving the closing member. A method of manufacturing a plastic pipe comprising an inner (1) and an outer wall (2) which, when forming longitudinal channels, are connected to each other by longitudinal connecting walls (3), characterized in that the pipe walls are heated at the ends of the channels to the required temperature. above, after which they are pressed tightly against each other and the end portions are expanded into a sleeve. Method according to Claim 2, characterized in that the pressing of the channel walls against one another is effected by subjecting the end region of the plastic tube to a slight rotation. Method according to Claim 1 or 3, characterized in that, after closing the end ends of the channels, the end of the tube itself is provided with a sleeve which either has a groove for fitting a closing member or is absent. A method according to claim 2, characterized in that after the groove is formed by the spreading pin (10), a rotating movement is applied to said spreading pin (10).